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OpenGL dramatic fps drop when using transparent texture

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Hi all,
it's my first post here and i plan to be more participative from now on.
Ill start with a problem i have in one application i did in visual C+GLUT+OpenGL.
As the title states, i have a dramatic drop in frames per second when using a single BMP texture with transparency and i think maybe the problem is that im not using the texture mapping correctly.

Without the displaying of transparent texture i get 50 frames per second which for me is okay. You can notice that the grass has a texture and also the sharks have dotted texture as skin.
[attachment=12710:fps 50.jpg]

In the following picture i draw the water walls i want without transparency i get 30 frames per second (20 fps drop) i dont understand why but anyway 30 fps seems to me a good framerate.
[attachment=12709:fps 30.jpg]

Now in this third image i add transparency for the water walls you can see the drop to 9 fps!!! And this i can't understand as i know dealing with transparency is one of the hardest things for GPUs but common, im using only one texture in 4 quads!!!!!
[attachment=12708:fps 9.jpg]

Here is the code i use:

[source lang="cpp"]void PintarCortinillasAgua(TcajaHueca *recinto, Tcontrol * control)
{
glMatrixMode(GL_MODELVIEW);
glPushMatrix();

if(control->texturas == VERDADERO)
{
glEnable(GL_TEXTURE_2D);
glEnable(GL_BLEND);

glBindTexture(GL_TEXTURE_2D, tex_agua.tex_Id);

glBlendFunc(GL_SRC_ALPHA,GL_ONE_MINUS_SRC_ALPHA);
glBegin(GL_POLYGON);//plano Zmax
glColor4f(1,1,1,0.4f);
glTexCoord2f( 0, 0 + offset_agua);
glVertex3f(recinto->min[X], recinto->min[Y], recinto->max[Z]);
glTexCoord2f( 5, 0 + offset_agua);
glVertex3f(recinto->max[X], recinto->min[Y], recinto->max[Z]);
glTexCoord2f( 5, 2 + offset_agua);
glVertex3f(recinto->max[X], recinto->max[Y], recinto->max[Z]);
glTexCoord2f( 0, 2 + offset_agua);
glVertex3f(recinto->min[X], recinto->max[Y], recinto->max[Z]);
glEnd();
glBegin(GL_POLYGON); //plano Xmax
glColor4f(1,1,1,0.4f);
glTexCoord2f( 0, 0 + offset_agua);
glVertex3f(recinto->max[X], recinto->min[Y], recinto->min[Z]);
glTexCoord2f( 5, 0 + offset_agua);
glVertex3f(recinto->max[X], recinto->min[Y], recinto->max[Z]);
glTexCoord2f( 5, 2 + offset_agua);
glVertex3f(recinto->max[X], recinto->max[Y], recinto->max[Z]);
glTexCoord2f( 0, 2 + offset_agua);
glVertex3f(recinto->max[X], recinto->max[Y], recinto->min[Z]);
glEnd();
glBegin(GL_POLYGON); //plano Zmin
glColor4f(1,1,1,0.4f);
glTexCoord2f( 0, 0 + offset_agua);
glVertex3f(recinto->min[X], recinto->min[Y], recinto->min[Z]);
glTexCoord2f( 5, 0 + offset_agua);
glVertex3f(recinto->max[X], recinto->min[Y], recinto->min[Z]);
glTexCoord2f( 5, 2 + offset_agua);
glVertex3f(recinto->max[X], recinto->max[Y], recinto->min[Z]);
glTexCoord2f( 0, 2 + offset_agua);
glVertex3f(recinto->min[X], recinto->max[Y], recinto->min[Z]);
glEnd();
glBegin(GL_POLYGON); //plano Xmin
glColor4f(1,1,1,0.4f);
glTexCoord2f( 0, 0 + offset_agua);
glVertex3f(recinto->min[X], recinto->min[Y], recinto->min[Z]);
glTexCoord2f( 5, 0 + offset_agua);
glVertex3f(recinto->min[X], recinto->min[Y], recinto->max[Z]);
glTexCoord2f( 5, 2 + offset_agua);
glVertex3f(recinto->min[X], recinto->max[Y], recinto->max[Z]);
glTexCoord2f( 0, 2 + offset_agua);
glVertex3f(recinto->min[X], recinto->max[Y], recinto->min[Z]);
glEnd();
glDisable(GL_TEXTURE_2D);
glDisable(GL_BLEND);
}
glPopMatrix();
}[/source]
The texture is a BMP image in REPEAT mode with blending set with glColor4f(1,1,1,0.4f).
Also i animate the texture mapping with an offset in the y direction to simulate falling water but this does not affect the fps drop.

What am i doing wrong??

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Okay i can say that i forgot to disable the GL_DEPTH_TEST and enable it at the end
[source lang="java"]glEnable(GL_BLEND)
glDisable(GL_DEPTH_TEST);

(draw stuff)

glEnable(GL_DEPTH_TEST);
glDisable(GL_BLEND);[/source]

I have ordered the drawing of the walls, first the 2 walls from the back and at last the 2 walls from the front, and apparently it works.....
[attachment=12717:fps 26 front.jpg]

... if it wasnt by the fact that i can rotate around Y axis and this is what happens:
[attachment=12716:fps 25 rotation problem.jpg]

now my back walls when i rotate around vertical Y axis the grass appears because it is rendered AFTER the back walls.


1. - What can i do to solve this problem? I can't find the correct draw order.
2. - If i dont disable GL_DEPTH_TESTING i get the correct behaviour but i get 9 fps!!!!
3. - I dont have anymore 9 fps but 25fps, why is this if i had at the beginning without the walls 55 fps? Why such difference in performance? Edited by fip

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What sort of graphics card are you using, and what sort of resolution and anti-aliasing setup is there?

The only explanation I can think of is that you're woefully fill rate bound, but I can't see how this scene could possibly cause that situation on a desktop graphics card (maybe an iPad1, but not anything else).

Plus a quick stupid question - you're not accidentally rendering the transparent quads multiple times are you?

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Your fps will always be garbage in intermediate mode, try using a draw list or vbo.

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In addition to the above, you shouldn't measure performance in FPS - measure in milliseconds or microseconds. FPS measurements can be deceptive; an increase from 55 FPS to 60 FPS (a gain of 1.5 ms a frame) is not the same increase as from 60 FPS to 65 FPS (a gain of 1.2 ms a frame).

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Can you post the output of glGetString(GL_VENDOR) ? If it is Microsoft, then you are running on some kind of emulation and need to install the drivers for your graphics card.

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Why are you using GL_POLYGON? you seem to be using just quads replacing GL_POLYGON with GL_QUADS should be faster. Also get rid of those extra glbegin/glend's in between each face.

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Can you post the output of glGetString(GL_VENDOR) ? If it is Microsoft, then you are running on some kind of emulation and need to install the drivers for your graphics card.


Ahh that's it!! i got "microsoft corporation" for GL_VENDOR and "GDI generic" for GL_RENDERER query!!.

Now, im running the app in a laptop Dell XPS17 with integrated graphics card and an Nvidia GT555m card, maybe the problem is im not choosing the right graphics card for running the app.

Now how the heck i do that?


Why are you using GL_POLYGON? you seem to be using just quads replacing GL_POLYGON with GL_QUADS should be faster. Also get rid of those extra glbegin/glend's in between each face.

Yeah you re right ill change it, thanks.

Your fps will always be garbage in intermediate mode, try using a draw list or vbo.


Display lists seem interesting ill dig into that. This was my first attempt messing with OpenGL

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Your fps will always be garbage in intermediate mode, try using a draw list or vbo.


No no no no no.

Immediate mode is slower than the other methods for sure, but it's not that much slower. You don't get such dramatic framerate drops from it, particularly with such a simple scene (as polycounts really ramp up it's expected, but with basic scenes it's performance is roughly equivalent to the others). Remember - Quake used immediate mode and didn't suffer overly much from it.

Please don't recommend VBOs (or display lists) as a "solution" every time you see immediate mode code - the real cause of the problem may very well be elsewhere (as, indeed, it was in this case).

I'm not advising that it's OK to use immediate mode here, by the way; I am recommending that you should properly diagnose the problem before recommending a solution, rather than jump to conclusions.


Now how the heck i do that?


You should have an option to select the GPU to use in your NVIDIA control panel. It's also worthwhile downloading updated drivers for your machine as the absence of a proper OpenGL driver for the integrated card suggests that you're on an OEM driver; visit http://www.nvidia.com/Download/index.aspx?lang=en-us to get a proper updated driver. Edited by mhagain

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[quote name='Kaze' timestamp='1355167357' post='5009164']
Your fps will always be garbage in intermediate mode, try using a draw list or vbo.


No no no no no.

Immediate mode is slower than the other methods for sure, but it's not that much slower. You don't get such dramatic framerate drops from it, particularly with such a simple scene (as polycounts really ramp up it's expected, but with basic scenes it's performance is roughly equivalent to the others). Remember - Quake used immediate mode and didn't suffer overly much from it.

Please don't recommend VBOs (or display lists) as a "solution" every time you see immediate mode code - the real cause of the problem may very well be elsewhere (as, indeed, it was in this case).

I'm not advising that it's OK to use immediate mode here, by the way; I am recommending that you should properly diagnose the problem before recommending a solution, rather than jump to conclusions.
[/quote]

Graphics card makers only optimize their hardware for vbo's these days so its not unreasonable to assume legacy functions can cause all sorts of performance problems. Edited by Kaze

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Ahh that's it!! i got "microsoft corporation" for GL_VENDOR and "GDI generic" for GL_RENDERER query!!.

Now, im running the app in a laptop Dell XPS17 with integrated graphics card and an Nvidia GT555m card, maybe the problem is im not choosing the right graphics card for running the app.<br /><br />Now how the heck i do that?
It's also worthwhile downloading updated drivers for your machine

^ This.

I encountered the same problem when I moved to Windows 8. Apparently Windows 8 thinks its half-baked display driver is better than the drivers provided by my graphic card's manufacturer...

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Hi, i have the nvidia control panel where i can select the .exe file related to whichever game i want to play and select which of the two video cards runs the game.

For game and other applications like adobe creative suite it works and it's the nvidia graphics card taking charge of.

But ive tried setting my application *.exe file in the list, and still wont run in the nvidia gt555m!! my Nvidia notifier says there are no programs running with the nvidia gpu plus the console spits out again GDI GENERIC plus no changes in fps of the app so it's definitely not working for me this way.

I've searched the internet but all i have found is people not knowing how to put the *.exe from a game in the list of the nvidia control panel, nothing about any programmer trying to run his own exe file in the nvidia gpu.......

Any ideas? Edited by fip

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Graphics card makers only optimize their hardware for vbo's these days so its not unreasonable to assume legacy functions can cause all sorts of performance problems.


Quake still runs well on a modern GPU (which is likely to be emulating immediate mode in the driver by filling a dynamic VBO behind the scenes) - certainly much faster than the single-digit framerates that the OP is reporting, and with much more complex geometry, translucency, etc. Yes, you're right that it's not unreasonable to make that assumption, but when actual hard data invalidates the assumption (for this class of simple scene) then you do need to reconsider.

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Ive downloaded lesson01 from nehe.gamedev.net opengl tutorials, the one that simply creates a window with rendering context and have noticed that the exe is being run by the nvidia gpu!!!

So, i guess it has to do either with the way glut manages window either with any initialization parameter im not setting properly..........

What do you guys think?

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So, i guess it has to do either with the way glut manages window either with any initialization parameter im not setting properly..........


Definitely possible. One unfortunate thing that many GLUT examples I've seen do is create a single-buffered context, and it may be the case that your NVIDIA GPU/driver is unable to give you a hardware accelerated one. If that sounds like something you may have in your code then switching it to double-buffered (using GLUT_DOUBLE during startup and adding a call to glutSwapBuffers at the end of each frame) may be all that you need. Also worth checking the bit depth you request for your colour and depth buffers (not sure if you can control this via GLUT though).

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I have double buffer specified in glut.

Ive spent some time porting my application to use SDL + OPENGL for window managing and input, and again i dont know why my gpu is not the GL_RENDERER i have again "GDI generic" !!!!

I have missed to try just creating a window in SDL and see if it renders on the gpu, ill try this tomorrow.

Maybe im using some opengl command that causes the software rendering?

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Hi,
Ive tested this SDL simple example and it doesnt run in my gpu neither.... although it initializes the video mode with SDL_OPENGL

example from http://lazyfoo.net/SDL_tutorials/lesson36/index.php

This is driving me nuts.............

I'll post my glut+Opengl window creation & initialization code soon, now i have to leave.

[source lang="cpp"]/*This source code copyrighted by Lazy Foo' Productions (2004-2012)
and may not be redistributed without written permission.*/

//The headers
#include "SDL.h"
#include "SDL_opengl.h"

//Screen attributes
const int SCREEN_WIDTH = 640;
const int SCREEN_HEIGHT = 480;
const int SCREEN_BPP = 32;

//The frame rate
const int FRAMES_PER_SECOND = 60;

//Event handler
SDL_Event event;

//Rendering flag
bool renderQuad = true;

//The timer
class Timer
{
private:
//The clock time when the timer started
int startTicks;

//The ticks stored when the timer was paused
int pausedTicks;

//The timer status
bool paused;
bool started;

public:
//Initializes variables
Timer();

//The various clock actions
void start();
void stop();
void pause();
void unpause();

//Gets the timer's time
int get_ticks();

//Checks the status of the timer
bool is_started();
bool is_paused();
};

bool initGL()
{
//Initialize Projection Matrix
glMatrixMode( GL_PROJECTION );
glLoadIdentity();

//Initialize Modelview Matrix
glMatrixMode( GL_MODELVIEW );
glLoadIdentity();

//Initialize clear color
glClearColor( 0.f, 0.f, 0.f, 1.f );

//Check for error
GLenum error = glGetError();
if( error != GL_NO_ERROR )
{
printf( "Error initializing OpenGL! %s\n", gluErrorString( error ) );
return false;
}

return true;
}

bool init()
{
//Initialize SDL
if( SDL_Init( SDL_INIT_EVERYTHING ) < 0 )
{
return false;
}

//Create Window
if( SDL_SetVideoMode( SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_BPP, SDL_OPENGL ) == NULL )
{
return false;
}

//Enable unicode
SDL_EnableUNICODE( SDL_TRUE );

//Initialize OpenGL
if( initGL() == false )
{
return false;
}

//Set caption
SDL_WM_SetCaption( "OpenGL Test", NULL );

return true;
}

void handleKeys( unsigned char key, int x, int y )
{
//Toggle quad
if( key == 'q' )
{
renderQuad = !renderQuad;
}
}

void update()
{

}

void render()
{
//Clear color buffer
glClear( GL_COLOR_BUFFER_BIT );

//Render quad
if( renderQuad == true )
{
glBegin( GL_QUADS );
glVertex2f( -0.5f, -0.5f );
glVertex2f( 0.5f, -0.5f );
glVertex2f( 0.5f, 0.5f );
glVertex2f( -0.5f, 0.5f );
glEnd();
}

//Update screen
SDL_GL_SwapBuffers();
}

void clean_up()
{
//Quit SDL
SDL_Quit();
}

Timer::Timer()
{
//Initialize the variables
startTicks = 0;
pausedTicks = 0;
paused = false;
started = false;
}

void Timer::start()
{
//Start the timer
started = true;

//Unpause the timer
paused = false;

//Get the current clock time
startTicks = SDL_GetTicks();
}

void Timer::stop()
{
//Stop the timer
started = false;

//Unpause the timer
paused = false;
}

void Timer::pause()
{
//If the timer is running and isn't already paused
if( ( started == true ) &amp;&amp; ( paused == false ) )
{
//Pause the timer
paused = true;

//Calculate the paused ticks
pausedTicks = SDL_GetTicks() - startTicks;
}
}

void Timer::unpause()
{
//If the timer is paused
if( paused == true )
{
//Unpause the timer
paused = false;

//Reset the starting ticks
startTicks = SDL_GetTicks() - pausedTicks;

//Reset the paused ticks
pausedTicks = 0;
}
}

int Timer::get_ticks()
{
//If the timer is running
if( started == true )
{
//If the timer is paused
if( paused == true )
{
//Return the number of ticks when the timer was paused
return pausedTicks;
}
else
{
//Return the current time minus the start time
return SDL_GetTicks() - startTicks;
}
}

//If the timer isn't running
return 0;
}

bool Timer::is_started()
{
return started;
}

bool Timer::is_paused()
{
return paused;
}

int main( int argc, char *argv[] )
{
//Quit flag
bool quit = false;

//Initialize
if( init() == false )
{
return 1;
}

//The frame rate regulator
Timer fps;

//Wait for user exit
while( quit == false )
{
//Start the frame timer
fps.start();

//While there are events to handle
while( SDL_PollEvent( &amp;event ) )
{
if( event.type == SDL_QUIT )
{
quit = true;
}
else if( event.type == SDL_KEYDOWN )
{
//Handle keypress with current mouse position
int x = 0, y = 0;
SDL_GetMouseState( &amp;x, &amp;y );
handleKeys( event.key.keysym.unicode, x, y );
}
}

//Run frame update
update();

//Render frame
render();

//Cap the frame rate
if( fps.get_ticks() < 1000 / FRAMES_PER_SECOND )
{
SDL_Delay( ( 1000 / FRAMES_PER_SECOND ) - fps.get_ticks() );
}
}

//Clean up
clean_up();

return 0;
}
[/source] Edited by fip

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OK, one problem here is that you're using SDL_Delay to control framerate. That's internally implemented as a Sleep call and Sleep is not a good way of controlling framerate (it only specifies a minimum time to sleep for; actual time may be longer, and this will be true even if using a high resolution timer).

That's not going to fix your specific problem with not getting a hardware accelerated GL context, but it is some cleaning up you need to do.

For your GL context problem, I'll have a look over your code later on today and see if I can spot anything (assuming someone else doesn't come up with the solution before then).

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Of course there is a driver problem there because with a scene light that you should run into the 300fps ballpark easily.
Having said that, blending operations will always have a big impact on the scene because simply, they do more work, they have to read the current pixel color, apply the blending function and then write back the colour.

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Hi again,

more testing:
- ive added
[source lang="cpp"]SDL_GL_SetAttribute( SDL_GL_ACCELERATED_VISUAL, 1);[/source]
does not have any effect. I think it should be enough with SDL_OPENGL but just in case.

- i ve run the executable on a notebook with only one GPU and i keep getting the "GDI generic" for GL_RENDERER.
So maybe it's not an issue of having dual gpus, furthermore in case it was using the intel HD integrated graphics card i should be getting "Intel" as the GL_VENDOR right?




OK, one problem here is that you're using SDL_Delay to control framerate.


It's just some code i grabbed from the internet. I dont care right now about this.


For your GL context problem, I'll have a look over your code later on today and see if I can spot anything (assuming someone else doesn't come up with the solution before then).

Thanks for your time, this is the problem i want to fix!!

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I tested this other SDL+Opengl code and still get GDI generic for GL_RENDERER.

[source lang="cpp"]#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <math.h>

#include "SDL.h"

#ifdef __MACOS__
#define HAVE_OPENGL
#endif

#define HAVE_OPENGL

#ifdef HAVE_OPENGL

#include "SDL_opengl.h"

/* Undefine this if you want a flat cube instead of a rainbow cube */
#define SHADED_CUBE

/* Define this to be the name of the logo image to use with -logo */
#define LOGO_FILE "icon.bmp"

/* The SDL_OPENGLBLIT interface is deprecated.
The code is still available for benchmark purposes though.
*/

static SDL_bool USE_DEPRECATED_OPENGLBLIT = SDL_FALSE;

static SDL_Surface *global_image = NULL;
static GLuint global_texture = 0;
static GLuint cursor_texture = 0;

/**********************************************************************/

void HotKey_ToggleFullScreen(void)
{
SDL_Surface *screen;

screen = SDL_GetVideoSurface();
if ( SDL_WM_ToggleFullScreen(screen) ) {
printf("Toggled fullscreen mode - now %s\n",
(screen->flags&SDL_FULLSCREEN) ? "fullscreen" : "windowed");
} else {
printf("Unable to toggle fullscreen mode\n");
}
}

void HotKey_ToggleGrab(void)
{
SDL_GrabMode mode;

printf("Ctrl-G: toggling input grab!\n");
mode = SDL_WM_GrabInput(SDL_GRAB_QUERY);
if ( mode == SDL_GRAB_ON ) {
printf("Grab was on\n");
} else {
printf("Grab was off\n");
}
mode = SDL_WM_GrabInput(!mode);
if ( mode == SDL_GRAB_ON ) {
printf("Grab is now on\n");
} else {
printf("Grab is now off\n");
}
}

void HotKey_Iconify(void)
{
printf("Ctrl-Z: iconifying window!\n");
SDL_WM_IconifyWindow();
}

int HandleEvent(SDL_Event *event)
{
int done;

done = 0;
switch( event->type ) {
case SDL_ACTIVEEVENT:
/* See what happened */
printf( "app %s ", event->active.gain ? "gained" : "lost" );
if ( event->active.state & SDL_APPACTIVE ) {
printf( "active " );
} else if ( event->active.state & SDL_APPMOUSEFOCUS ) {
printf( "mouse " );
} else if ( event->active.state & SDL_APPINPUTFOCUS ) {
printf( "input " );
}
printf( "focus\n" );
break;


case SDL_KEYDOWN:
if ( event->key.keysym.sym == SDLK_ESCAPE ) {
done = 1;
}
if ( (event->key.keysym.sym == SDLK_g) &&
(event->key.keysym.mod & KMOD_CTRL) ) {
HotKey_ToggleGrab();
}
if ( (event->key.keysym.sym == SDLK_z) &&
(event->key.keysym.mod & KMOD_CTRL) ) {
HotKey_Iconify();
}
if ( (event->key.keysym.sym == SDLK_RETURN) &&
(event->key.keysym.mod & KMOD_ALT) ) {
HotKey_ToggleFullScreen();
}
printf("key '%s' pressed\n",
SDL_GetKeyName(event->key.keysym.sym));
break;
case SDL_QUIT:
done = 1;
break;
}
return(done);
}

void SDL_GL_Enter2DMode()
{
SDL_Surface *screen = SDL_GetVideoSurface();

/* Note, there may be other things you need to change,
depending on how you have your OpenGL state set up.
*/
glPushAttrib(GL_ENABLE_BIT);
glDisable(GL_DEPTH_TEST);
glDisable(GL_CULL_FACE);
glEnable(GL_TEXTURE_2D);

/* This allows alpha blending of 2D textures with the scene */
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

glViewport(0, 0, screen->w, screen->h);

glMatrixMode(GL_PROJECTION);
glPushMatrix();
glLoadIdentity();

glOrtho(0.0, (GLdouble)screen->w, (GLdouble)screen->h, 0.0, 0.0, 1.0);

glMatrixMode(GL_MODELVIEW);
glPushMatrix();
glLoadIdentity();

glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);
}

void SDL_GL_Leave2DMode()
{
glMatrixMode(GL_MODELVIEW);
glPopMatrix();

glMatrixMode(GL_PROJECTION);
glPopMatrix();

glPopAttrib();
}

/* Quick utility function for texture creation */
static int power_of_two(int input)
{
int value = 1;

while ( value < input ) {
value <<= 1;
}
return value;
}

GLuint SDL_GL_LoadTexture(SDL_Surface *surface, GLfloat *texcoord)
{
GLuint texture;
int w, h;
SDL_Surface *image;
SDL_Rect area;
Uint32 saved_flags;
Uint8 saved_alpha;

/* Use the surface width and height expanded to powers of 2 */
w = power_of_two(surface->w);
h = power_of_two(surface->h);
texcoord[0] = 0.0f; /* Min X */
texcoord[1] = 0.0f; /* Min Y */
texcoord[2] = (GLfloat)surface->w / w; /* Max X */
texcoord[3] = (GLfloat)surface->h / h; /* Max Y */

image = SDL_CreateRGBSurface(
SDL_SWSURFACE,
w, h,
32,
#if SDL_BYTEORDER == SDL_LIL_ENDIAN /* OpenGL RGBA masks */
0x000000FF,
0x0000FF00,
0x00FF0000,
0xFF000000
#else
0xFF000000,
0x00FF0000,
0x0000FF00,
0x000000FF
#endif
);
if ( image == NULL ) {
return 0;
}

/* Save the alpha blending attributes */
saved_flags = surface->flags&(SDL_SRCALPHA|SDL_RLEACCELOK);
saved_alpha = surface->format->alpha;
if ( (saved_flags & SDL_SRCALPHA) == SDL_SRCALPHA ) {
SDL_SetAlpha(surface, 0, 0);
}

/* Copy the surface into the GL texture image */
area.x = 0;
area.y = 0;
area.w = surface->w;
area.h = surface->h;
SDL_BlitSurface(surface, &area, image, &area);

/* Restore the alpha blending attributes */
if ( (saved_flags & SDL_SRCALPHA) == SDL_SRCALPHA ) {
SDL_SetAlpha(surface, saved_flags, saved_alpha);
}

/* Create an OpenGL texture for the image */
glGenTextures(1, &texture);
glBindTexture(GL_TEXTURE_2D, texture);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexImage2D(GL_TEXTURE_2D,
0,
GL_RGBA,
w, h,
0,
GL_RGBA,
GL_UNSIGNED_BYTE,
image->pixels);
SDL_FreeSurface(image); /* No longer needed */

return texture;
}

void DrawLogoCursor(void)
{
static GLfloat texMinX, texMinY;
static GLfloat texMaxX, texMaxY;
static int w, h;
int x, y;

if ( ! cursor_texture ) {
SDL_Surface *image;
GLfloat texcoord[4];

/* Load the image (could use SDL_image library here) */
image = SDL_LoadBMP(LOGO_FILE);
if ( image == NULL ) {
return;
}
w = image->w;
h = image->h;

/* Convert the image into an OpenGL texture */
cursor_texture = SDL_GL_LoadTexture(image, texcoord);

/* Make texture coordinates easy to understand */
texMinX = texcoord[0];
texMinY = texcoord[1];
texMaxX = texcoord[2];
texMaxY = texcoord[3];

/* We don't need the original image anymore */
SDL_FreeSurface(image);

/* Make sure that the texture conversion is okay */
if ( ! cursor_texture ) {
return;
}
}

/* Move the image around */
SDL_GetMouseState(&x, &y);
x -= w/2;
y -= h/2;

/* Show the image on the screen */
SDL_GL_Enter2DMode();
glBindTexture(GL_TEXTURE_2D, cursor_texture);
glBegin(GL_TRIANGLE_STRIP);
glTexCoord2f(texMinX, texMinY); glVertex2i(x, y );
glTexCoord2f(texMaxX, texMinY); glVertex2i(x+w, y );
glTexCoord2f(texMinX, texMaxY); glVertex2i(x, y+h);
glTexCoord2f(texMaxX, texMaxY); glVertex2i(x+w, y+h);
glEnd();
SDL_GL_Leave2DMode();
}

void DrawLogoTexture(void)
{
static GLfloat texMinX, texMinY;
static GLfloat texMaxX, texMaxY;
static int x = 0;
static int y = 0;
static int w, h;
static int delta_x = 1;
static int delta_y = 1;

SDL_Surface *screen = SDL_GetVideoSurface();

if ( ! global_texture ) {
SDL_Surface *image;
GLfloat texcoord[4];

/* Load the image (could use SDL_image library here) */
image = SDL_LoadBMP(LOGO_FILE);
if ( image == NULL ) {
return;
}
w = image->w;
h = image->h;

/* Convert the image into an OpenGL texture */
global_texture = SDL_GL_LoadTexture(image, texcoord);

/* Make texture coordinates easy to understand */
texMinX = texcoord[0];
texMinY = texcoord[1];
texMaxX = texcoord[2];
texMaxY = texcoord[3];

/* We don't need the original image anymore */
SDL_FreeSurface(image);

/* Make sure that the texture conversion is okay */
if ( ! global_texture ) {
return;
}
}

/* Move the image around */
x += delta_x;
if ( x < 0 ) {
x = 0;
delta_x = -delta_x;
} else
if ( (x+w) > screen->w ) {
x = screen->w-w;
delta_x = -delta_x;
}
y += delta_y;
if ( y < 0 ) {
y = 0;
delta_y = -delta_y;
} else
if ( (y+h) > screen->h ) {
y = screen->h-h;
delta_y = -delta_y;
}

/* Show the image on the screen */
SDL_GL_Enter2DMode();
glBindTexture(GL_TEXTURE_2D, global_texture);
glBegin(GL_TRIANGLE_STRIP);
glTexCoord2f(texMinX, texMinY); glVertex2i(x, y );
glTexCoord2f(texMaxX, texMinY); glVertex2i(x+w, y );
glTexCoord2f(texMinX, texMaxY); glVertex2i(x, y+h);
glTexCoord2f(texMaxX, texMaxY); glVertex2i(x+w, y+h);
glEnd();
SDL_GL_Leave2DMode();
}

/* This code is deprecated, but available for speed comparisons */
void DrawLogoBlit(void)
{
static int x = 0;
static int y = 0;
static int w, h;
static int delta_x = 1;
static int delta_y = 1;

SDL_Rect dst;
SDL_Surface *screen = SDL_GetVideoSurface();

if ( global_image == NULL ) {
SDL_Surface *temp;

/* Load the image (could use SDL_image library here) */
temp = SDL_LoadBMP(LOGO_FILE);
if ( temp == NULL ) {
return;
}
w = temp->w;
h = temp->h;

/* Convert the image into the screen format */
global_image = SDL_CreateRGBSurface(
SDL_SWSURFACE,
w, h,
screen->format->BitsPerPixel,
screen->format->Rmask,
screen->format->Gmask,
screen->format->Bmask,
screen->format->Amask);
if ( global_image ) {
SDL_BlitSurface(temp, NULL, global_image, NULL);
}
SDL_FreeSurface(temp);

/* Make sure that the texture conversion is okay */
if ( ! global_image ) {
return;
}
}

/* Move the image around
Note that we do not clear the old position. This is because we
perform a glClear() which clears the framebuffer and then only
update the new area.
Note that you can also achieve interesting effects by modifying
the screen surface alpha channel. It's set to 255 by default..
*/
x += delta_x;
if ( x < 0 ) {
x = 0;
delta_x = -delta_x;
} else
if ( (x+w) > screen->w ) {
x = screen->w-w;
delta_x = -delta_x;
}
y += delta_y;
if ( y < 0 ) {
y = 0;
delta_y = -delta_y;
} else
if ( (y+h) > screen->h ) {
y = screen->h-h;
delta_y = -delta_y;
}
dst.x = x;
dst.y = y;
dst.w = w;
dst.h = h;
SDL_BlitSurface(global_image, NULL, screen, &dst);

/* Show the image on the screen */
SDL_UpdateRects(screen, 1, &dst);
}

int RunGLTest( int argc, char* argv[],
int logo, int logocursor, int slowly, int bpp, float gamma, int noframe, int fsaa, int sync, int accel )
{
int i;
int rgb_size[3];
int w = 640;
int h = 480;
int done = 0;
int frames;
Uint32 start_time, this_time;
float color[8][3]= {{ 1.0, 1.0, 0.0},
{ 1.0, 0.0, 0.0},
{ 0.0, 0.0, 0.0},
{ 0.0, 1.0, 0.0},
{ 0.0, 1.0, 1.0},
{ 1.0, 1.0, 1.0},
{ 1.0, 0.0, 1.0},
{ 0.0, 0.0, 1.0}};
float cube[8][3]= {{ 0.5, 0.5, -0.5},
{ 0.5, -0.5, -0.5},
{-0.5, -0.5, -0.5},
{-0.5, 0.5, -0.5},
{-0.5, 0.5, 0.5},
{ 0.5, 0.5, 0.5},
{ 0.5, -0.5, 0.5},
{-0.5, -0.5, 0.5}};
Uint32 video_flags;
int value;

if( SDL_Init( SDL_INIT_VIDEO ) < 0 ) {
fprintf(stderr,"Couldn't initialize SDL: %s\n",SDL_GetError());
exit( 1 );
}

/* See if we should detect the display depth */
if ( bpp == 0 ) {
if ( SDL_GetVideoInfo()->vfmt->BitsPerPixel <= 8 ) {
bpp = 8;
} else {
bpp = 16; /* More doesn't seem to work */
}
}

/* Set the flags we want to use for setting the video mode */
if ( logo && USE_DEPRECATED_OPENGLBLIT ) {
video_flags = SDL_OPENGLBLIT;
} else {
video_flags = SDL_OPENGL;
}
for ( i=1; argv; ++i ) {
if ( strcmp(argv, "-fullscreen") == 0 ) {
video_flags |= SDL_FULLSCREEN;
}
}

if (noframe) {
video_flags |= SDL_NOFRAME;
}

/* Initialize the display */
switch (bpp) {
case 8:
rgb_size[0] = 3;
rgb_size[1] = 3;
rgb_size[2] = 2;
break;
case 15:
case 16:
rgb_size[0] = 5;
rgb_size[1] = 5;
rgb_size[2] = 5;
break;
default:
rgb_size[0] = 8;
rgb_size[1] = 8;
rgb_size[2] = 8;
break;
}
SDL_GL_SetAttribute( SDL_GL_RED_SIZE, rgb_size[0] );
SDL_GL_SetAttribute( SDL_GL_GREEN_SIZE, rgb_size[1] );
SDL_GL_SetAttribute( SDL_GL_BLUE_SIZE, rgb_size[2] );
SDL_GL_SetAttribute( SDL_GL_DEPTH_SIZE, 16 );
SDL_GL_SetAttribute( SDL_GL_DOUBLEBUFFER, 1 );
if ( fsaa ) {
SDL_GL_SetAttribute( SDL_GL_MULTISAMPLEBUFFERS, 1 );
SDL_GL_SetAttribute( SDL_GL_MULTISAMPLESAMPLES, fsaa );
}
if ( accel ) {
SDL_GL_SetAttribute( SDL_GL_ACCELERATED_VISUAL, 1 );
}
if ( sync ) {
SDL_GL_SetAttribute( SDL_GL_SWAP_CONTROL, 1 );
} else {
SDL_GL_SetAttribute( SDL_GL_SWAP_CONTROL, 0 );
}
if ( SDL_SetVideoMode( w, h, bpp, video_flags ) == NULL ) {
fprintf(stderr, "Couldn't set GL mode: %s\n", SDL_GetError());
SDL_Quit();
exit(1);
}

printf("Screen BPP: %d\n", SDL_GetVideoSurface()->format->BitsPerPixel);
printf("\n");
printf( "Vendor : %s\n", glGetString( GL_VENDOR ) );
printf( "Renderer : %s\n", glGetString( GL_RENDERER ) );
printf( "Version : %s\n", glGetString( GL_VERSION ) );
printf( "Extensions : %s\n", glGetString( GL_EXTENSIONS ) );
printf("\n");

SDL_GL_GetAttribute( SDL_GL_RED_SIZE, &value );
printf( "SDL_GL_RED_SIZE: requested %d, got %d\n", rgb_size[0],value);
SDL_GL_GetAttribute( SDL_GL_GREEN_SIZE, &value );
printf( "SDL_GL_GREEN_SIZE: requested %d, got %d\n", rgb_size[1],value);
SDL_GL_GetAttribute( SDL_GL_BLUE_SIZE, &value );
printf( "SDL_GL_BLUE_SIZE: requested %d, got %d\n", rgb_size[2],value);
SDL_GL_GetAttribute( SDL_GL_DEPTH_SIZE, &value );
printf( "SDL_GL_DEPTH_SIZE: requested %d, got %d\n", bpp, value );
SDL_GL_GetAttribute( SDL_GL_DOUBLEBUFFER, &value );
printf( "SDL_GL_DOUBLEBUFFER: requested 1, got %d\n", value );
if ( fsaa ) {
SDL_GL_GetAttribute( SDL_GL_MULTISAMPLEBUFFERS, &value );
printf("SDL_GL_MULTISAMPLEBUFFERS: requested 1, got %d\n", value );
SDL_GL_GetAttribute( SDL_GL_MULTISAMPLESAMPLES, &value );
printf("SDL_GL_MULTISAMPLESAMPLES: requested %d, got %d\n", fsaa, value );
}
if ( accel ) {
SDL_GL_GetAttribute( SDL_GL_ACCELERATED_VISUAL, &value );
printf( "SDL_GL_ACCELERATED_VISUAL: requested 1, got %d\n", value );
}
if ( sync ) {
SDL_GL_GetAttribute( SDL_GL_SWAP_CONTROL, &value );
printf( "SDL_GL_SWAP_CONTROL: requested 1, got %d\n", value );
}

/* Set the window manager title bar */
SDL_WM_SetCaption( "SDL GL test", "testgl" );

/* Set the gamma for the window */
if ( gamma != 0.0 ) {
SDL_SetGamma(gamma, gamma, gamma);
}

glViewport( 0, 0, w, h );
glMatrixMode( GL_PROJECTION );
glLoadIdentity( );

glOrtho( -2.0, 2.0, -2.0, 2.0, -20.0, 20.0 );

glMatrixMode( GL_MODELVIEW );
glLoadIdentity( );

glEnable(GL_DEPTH_TEST);

glDepthFunc(GL_LESS);

glShadeModel(GL_SMOOTH);

/* Loop until done. */
start_time = SDL_GetTicks();
frames = 0;
while( !done ) {
GLenum gl_error;
char* sdl_error;
SDL_Event event;

/* Do our drawing, too. */
glClearColor( 0.0, 0.0, 0.0, 1.0 );
glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

glBegin( GL_QUADS );

#ifdef SHADED_CUBE
glColor3fv(color[0]);
glVertex3fv(cube[0]);
glColor3fv(color[1]);
glVertex3fv(cube[1]);
glColor3fv(color[2]);
glVertex3fv(cube[2]);
glColor3fv(color[3]);
glVertex3fv(cube[3]);

glColor3fv(color[3]);
glVertex3fv(cube[3]);
glColor3fv(color[4]);
glVertex3fv(cube[4]);
glColor3fv(color[7]);
glVertex3fv(cube[7]);
glColor3fv(color[2]);
glVertex3fv(cube[2]);

glColor3fv(color[0]);
glVertex3fv(cube[0]);
glColor3fv(color[5]);
glVertex3fv(cube[5]);
glColor3fv(color[6]);
glVertex3fv(cube[6]);
glColor3fv(color[1]);
glVertex3fv(cube[1]);

glColor3fv(color[5]);
glVertex3fv(cube[5]);
glColor3fv(color[4]);
glVertex3fv(cube[4]);
glColor3fv(color[7]);
glVertex3fv(cube[7]);
glColor3fv(color[6]);
glVertex3fv(cube[6]);

glColor3fv(color[5]);
glVertex3fv(cube[5]);
glColor3fv(color[0]);
glVertex3fv(cube[0]);
glColor3fv(color[3]);
glVertex3fv(cube[3]);
glColor3fv(color[4]);
glVertex3fv(cube[4]);

glColor3fv(color[6]);
glVertex3fv(cube[6]);
glColor3fv(color[1]);
glVertex3fv(cube[1]);
glColor3fv(color[2]);
glVertex3fv(cube[2]);
glColor3fv(color[7]);
glVertex3fv(cube[7]);
#else /* flat cube */
glColor3f(1.0, 0.0, 0.0);
glVertex3fv(cube[0]);
glVertex3fv(cube[1]);
glVertex3fv(cube[2]);
glVertex3fv(cube[3]);

glColor3f(0.0, 1.0, 0.0);
glVertex3fv(cube[3]);
glVertex3fv(cube[4]);
glVertex3fv(cube[7]);
glVertex3fv(cube[2]);

glColor3f(0.0, 0.0, 1.0);
glVertex3fv(cube[0]);
glVertex3fv(cube[5]);
glVertex3fv(cube[6]);
glVertex3fv(cube[1]);

glColor3f(0.0, 1.0, 1.0);
glVertex3fv(cube[5]);
glVertex3fv(cube[4]);
glVertex3fv(cube[7]);
glVertex3fv(cube[6]);

glColor3f(1.0, 1.0, 0.0);
glVertex3fv(cube[5]);
glVertex3fv(cube[0]);
glVertex3fv(cube[3]);
glVertex3fv(cube[4]);

glColor3f(1.0, 0.0, 1.0);
glVertex3fv(cube[6]);
glVertex3fv(cube[1]);
glVertex3fv(cube[2]);
glVertex3fv(cube[7]);
#endif /* SHADED_CUBE */

glEnd( );

glMatrixMode(GL_MODELVIEW);
glRotatef(5.0, 1.0, 1.0, 1.0);

/* Draw 2D logo onto the 3D display */
if ( logo ) {
if ( USE_DEPRECATED_OPENGLBLIT ) {
DrawLogoBlit();
} else {
DrawLogoTexture();
}
}
if ( logocursor ) {
DrawLogoCursor();
}

SDL_GL_SwapBuffers( );

/* Check for error conditions. */
gl_error = glGetError( );

if( gl_error != GL_NO_ERROR ) {
fprintf( stderr, "testgl: OpenGL error: %d\n", gl_error );
}

sdl_error = SDL_GetError( );

if( sdl_error[0] != '\0' ) {
fprintf(stderr, "testgl: SDL error '%s'\n", sdl_error);
SDL_ClearError();
}

/* Allow the user to see what's happening */
if ( slowly ) {
SDL_Delay( 20 );
}

/* Check if there's a pending event. */
while( SDL_PollEvent( &event ) ) {
done = HandleEvent(&event);
}
++frames;
}

/* Print out the frames per second */
this_time = SDL_GetTicks();
if ( this_time != start_time ) {
printf("%2.2f FPS\n",
((float)frames/(this_time-start_time))*1000.0);
}

if ( global_image ) {
SDL_FreeSurface(global_image);
global_image = NULL;
}
if ( global_texture ) {
glDeleteTextures( 1, &global_texture );
global_texture = 0;
}
if ( cursor_texture ) {
glDeleteTextures( 1, &cursor_texture );
cursor_texture = 0;
}

/* Destroy our GL context, etc. */
SDL_Quit( );
return(0);
}

int main(int argc, char *argv[])
{
int i, logo, logocursor = 0;
int numtests;
int bpp = 0;
int slowly;
float gamma = 0.0;
int noframe = 0;
int fsaa = 0;
int accel = 0;
int sync = 0;

logo = 0;
slowly = 0;
numtests = 1;
for ( i=1; argv; ++i ) {
if ( strcmp(argv, "-twice") == 0 ) {
++numtests;
}
if ( strcmp(argv, "-logo") == 0 ) {
logo = 1;
USE_DEPRECATED_OPENGLBLIT = SDL_FALSE;
}
if ( strcmp(argv, "-logoblit") == 0 ) {
logo = 1;
USE_DEPRECATED_OPENGLBLIT = SDL_TRUE;
}
if ( strcmp(argv, "-logocursor") == 0 ) {
logocursor = 1;
}
if ( strcmp(argv, "-slow") == 0 ) {
slowly = 1;
}
if ( strcmp(argv, "-bpp") == 0 ) {
bpp = atoi(argv[++i]);
}
if ( strcmp(argv, "-gamma") == 0 ) {
gamma = (float)atof(argv[++i]);
}
if ( strcmp(argv, "-noframe") == 0 ) {
noframe = 1;
}
if ( strcmp(argv, "-fsaa") == 0 ) {
++fsaa;
}
if ( strcmp(argv, "-accel") == 0 ) {
++accel;
}
if ( strcmp(argv, "-sync") == 0 ) {
++sync;
}
if ( strncmp(argv, "-h", 2) == 0 ) {
printf(
"Usage: %s [-twice] [-logo] [-logocursor] [-slow] [-bpp n] [-gamma n] [-noframe] [-fsaa] [-accel] [-sync] [-fullscreen]\n",
argv[0]);
exit(0);
}
}
for ( i=0; i<numtests; ++i ) {
RunGLTest(argc, argv, logo, logocursor, slowly, bpp, gamma, noframe, fsaa, sync, accel);
}
return 0;
}

#else /* HAVE_OPENGL */

int main(int argc, char *argv[])
{
printf("No OpenGL support on this system\n");
return 1;
}

#endif /* HAVE_OPENGL */[/source]

Can someone try to run this code and see what do you get for GL_RENDERER?

I want to know if the problem is in the code or it's in my laptop configuration somehow.

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Here's what I get on one machine:

Vendor : ATI Technologies Inc.
Renderer : AMD Radeon HD 6450
Version : 4.2.11931 Compatibility Profile Context
SDL_GL_RED_SIZE: requested 5, got 8
SDL_GL_GREEN_SIZE: requested 5, got 8
SDL_GL_BLUE_SIZE: requested 5, got 8
SDL_GL_DEPTH_SIZE: requested 16, got 24
SDL_GL_DOUBLEBUFFER: requested 1, got 1[/quote]

What looks possible here is that you're requesting default modes that may not be available in hardware-accelerated versions. 16-bit modes are really really old these days (the last video card that didn't support 32-bit colour was the Voodoo 3) and there should be no reason to go looking for one - try bumping RGB to 8/8/8 and see what that gets you.

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the most likely cause is that you don't have a driver from nvidia. Go on the nvidia website, download and install your driver and enjoy hardware accelerated OpenGL.

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Hi mhagain,
Here is what i get after increasing the depth size to 24:


Screen BPP: 24
Vendor : Microsoft Corporation
Renderer : GDI Generic
Version : 1.1.0
Extensions : GL_WIN_swap_hint GL_EXT_bgr
SDL_GL_RED_SIZE: requested 8, got 8
SDL_GL_GREEN_SIZE: requested 8, got 8
SDL_GL_BLUE_SIZE: requested 8, got 8
SDL_GL_DEPTH_SIZE: requested 24, got 32
SDL_GL_DOUBLEBUFFER: requested 1, got 1
[/Quote]

I think i have spotted the problem.
In the official opengl documentation site ive found this http://www.opengl.org/archives/resources/faq/technical/mswindows.htm specially the point "5.030 How do I enable and disable hardware rendering on a Wintel card?"
It says that hardware acceleration depends on choosing a right PIXEL FORMAT. Now is it possible to do this when you are using GLUT? Which config do i need when using SDL to get hardware acceleration?

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      Graphics APIs have come a long way from small set of basic commands allowing limited control of configurable stages of early 3D accelerators to very low-level programming interfaces exposing almost every aspect of the underlying graphics hardware. Next-generation APIs, Direct3D12 by Microsoft and Vulkan by Khronos are relatively new and have only started getting widespread adoption and support from hardware vendors, while Direct3D11 and OpenGL are still considered industry standard. New APIs can provide substantial performance and functional improvements, but may not be supported by older hardware. An application targeting wide range of platforms needs to support Direct3D11 and OpenGL. New APIs will not give any advantage when used with old paradigms. It is totally possible to add Direct3D12 support to an existing renderer by implementing Direct3D11 interface through Direct3D12, but this will give zero benefits. Instead, new approaches and rendering architectures that leverage flexibility provided by the next-generation APIs are expected to be developed.
      There are at least four APIs (Direct3D11, Direct3D12, OpenGL/GLES, Vulkan, plus Apple's Metal for iOS and osX platforms) that a cross-platform 3D application may need to support. Writing separate code paths for all APIs is clearly not an option for any real-world application and the need for a cross-platform graphics abstraction layer is evident. The following is the list of requirements that I believe such layer needs to satisfy:
      Lightweight abstractions: the API should be as close to the underlying native APIs as possible to allow an application leverage all available low-level functionality. In many cases this requirement is difficult to achieve because specific features exposed by different APIs may vary considerably. Low performance overhead: the abstraction layer needs to be efficient from performance point of view. If it introduces considerable amount of overhead, there is no point in using it. Convenience: the API needs to be convenient to use. It needs to assist developers in achieving their goals not limiting their control of the graphics hardware. Multithreading: ability to efficiently parallelize work is in the core of Direct3D12 and Vulkan and one of the main selling points of the new APIs. Support for multithreading in a cross-platform layer is a must. Extensibility: no matter how well the API is designed, it still introduces some level of abstraction. In some cases the most efficient way to implement certain functionality is to directly use native API. The abstraction layer needs to provide seamless interoperability with the underlying native APIs to provide a way for the app to add features that may be missing. Diligent Engine is designed to solve these problems. Its main goal is to take advantages of the next-generation APIs such as Direct3D12 and Vulkan, but at the same time provide support for older platforms via Direct3D11, OpenGL and OpenGLES. Diligent Engine exposes common C++ front-end for all supported platforms and provides interoperability with underlying native APIs. It also supports integration with Unity and is designed to be used as graphics subsystem in a standalone game engine, Unity native plugin or any other 3D application. Full source code is available for download at GitHub and is free to use.
      Overview
      Diligent Engine API takes some features from Direct3D11 and Direct3D12 as well as introduces new concepts to hide certain platform-specific details and make the system easy to use. It contains the following main components:
      Render device (IRenderDevice  interface) is responsible for creating all other objects (textures, buffers, shaders, pipeline states, etc.).
      Device context (IDeviceContext interface) is the main interface for recording rendering commands. Similar to Direct3D11, there are immediate context and deferred contexts (which in Direct3D11 implementation map directly to the corresponding context types). Immediate context combines command queue and command list recording functionality. It records commands and submits the command list for execution when it contains sufficient number of commands. Deferred contexts are designed to only record command lists that can be submitted for execution through the immediate context.
      An alternative way to design the API would be to expose command queue and command lists directly. This approach however does not map well to Direct3D11 and OpenGL. Besides, some functionality (such as dynamic descriptor allocation) can be much more efficiently implemented when it is known that a command list is recorded by a certain deferred context from some thread.
      The approach taken in the engine does not limit scalability as the application is expected to create one deferred context per thread, and internally every deferred context records a command list in lock-free fashion. At the same time this approach maps well to older APIs.
      In current implementation, only one immediate context that uses default graphics command queue is created. To support multiple GPUs or multiple command queue types (compute, copy, etc.), it is natural to have one immediate contexts per queue. Cross-context synchronization utilities will be necessary.
      Swap Chain (ISwapChain interface). Swap chain interface represents a chain of back buffers and is responsible for showing the final rendered image on the screen.
      Render device, device contexts and swap chain are created during the engine initialization.
      Resources (ITexture and IBuffer interfaces). There are two types of resources - textures and buffers. There are many different texture types (2D textures, 3D textures, texture array, cubmepas, etc.) that can all be represented by ITexture interface.
      Resources Views (ITextureView and IBufferView interfaces). While textures and buffers are mere data containers, texture views and buffer views describe how the data should be interpreted. For instance, a 2D texture can be used as a render target for rendering commands or as a shader resource.
      Pipeline State (IPipelineState interface). GPU pipeline contains many configurable stages (depth-stencil, rasterizer and blend states, different shader stage, etc.). Direct3D11 uses coarse-grain objects to set all stage parameters at once (for instance, a rasterizer object encompasses all rasterizer attributes), while OpenGL contains myriad functions to fine-grain control every individual attribute of every stage. Both methods do not map very well to modern graphics hardware that combines all states into one monolithic state under the hood. Direct3D12 directly exposes pipeline state object in the API, and Diligent Engine uses the same approach.
      Shader Resource Binding (IShaderResourceBinding interface). Shaders are programs that run on the GPU. Shaders may access various resources (textures and buffers), and setting correspondence between shader variables and actual resources is called resource binding. Resource binding implementation varies considerably between different API. Diligent Engine introduces a new object called shader resource binding that encompasses all resources needed by all shaders in a certain pipeline state.
      API Basics
      Creating Resources
      Device resources are created by the render device. The two main resource types are buffers, which represent linear memory, and textures, which use memory layouts optimized for fast filtering. Graphics APIs usually have a native object that represents linear buffer. Diligent Engine uses IBuffer interface as an abstraction for a native buffer. To create a buffer, one needs to populate BufferDesc structure and call IRenderDevice::CreateBuffer() method as in the following example:
      BufferDesc BuffDesc; BufferDesc.Name = "Uniform buffer"; BuffDesc.BindFlags = BIND_UNIFORM_BUFFER; BuffDesc.Usage = USAGE_DYNAMIC; BuffDesc.uiSizeInBytes = sizeof(ShaderConstants); BuffDesc.CPUAccessFlags = CPU_ACCESS_WRITE; m_pDevice->CreateBuffer( BuffDesc, BufferData(), &m_pConstantBuffer ); While there is usually just one buffer object, different APIs use very different approaches to represent textures. For instance, in Direct3D11, there are ID3D11Texture1D, ID3D11Texture2D, and ID3D11Texture3D objects. In OpenGL, there is individual object for every texture dimension (1D, 2D, 3D, Cube), which may be a texture array, which may also be multisampled (i.e. GL_TEXTURE_2D_MULTISAMPLE_ARRAY). As a result there are nine different GL texture types that Diligent Engine may create under the hood. In Direct3D12, there is only one resource interface. Diligent Engine hides all these details in ITexture interface. There is only one  IRenderDevice::CreateTexture() method that is capable of creating all texture types. Dimension, format, array size and all other parameters are specified by the members of the TextureDesc structure:
      TextureDesc TexDesc; TexDesc.Name = "My texture 2D"; TexDesc.Type = TEXTURE_TYPE_2D; TexDesc.Width = 1024; TexDesc.Height = 1024; TexDesc.Format = TEX_FORMAT_RGBA8_UNORM; TexDesc.Usage = USAGE_DEFAULT; TexDesc.BindFlags = BIND_SHADER_RESOURCE | BIND_RENDER_TARGET | BIND_UNORDERED_ACCESS; TexDesc.Name = "Sample 2D Texture"; m_pRenderDevice->CreateTexture( TexDesc, TextureData(), &m_pTestTex ); If native API supports multithreaded resource creation, textures and buffers can be created by multiple threads simultaneously.
      Interoperability with native API provides access to the native buffer/texture objects and also allows creating Diligent Engine objects from native handles. It allows applications seamlessly integrate native API-specific code with Diligent Engine.
      Next-generation APIs allow fine level-control over how resources are allocated. Diligent Engine does not currently expose this functionality, but it can be added by implementing IResourceAllocator interface that encapsulates specifics of resource allocation and providing this interface to CreateBuffer() or CreateTexture() methods. If null is provided, default allocator should be used.
      Initializing the Pipeline State
      As it was mentioned earlier, Diligent Engine follows next-gen APIs to configure the graphics/compute pipeline. One big Pipelines State Object (PSO) encompasses all required states (all shader stages, input layout description, depth stencil, rasterizer and blend state descriptions etc.). This approach maps directly to Direct3D12/Vulkan, but is also beneficial for older APIs as it eliminates pipeline misconfiguration errors. With many individual calls tweaking various GPU pipeline settings it is very easy to forget to set one of the states or assume the stage is already properly configured when in fact it is not. Using pipeline state object helps avoid these problems as all stages are configured at once.
      Creating Shaders
      While in earlier APIs shaders were bound separately, in the next-generation APIs as well as in Diligent Engine shaders are part of the pipeline state object. The biggest challenge when authoring shaders is that Direct3D and OpenGL/Vulkan use different shader languages (while Apple uses yet another language in their Metal API). Maintaining two versions of every shader is not an option for real applications and Diligent Engine implements shader source code converter that allows shaders authored in HLSL to be translated to GLSL. To create a shader, one needs to populate ShaderCreationAttribs structure. SourceLanguage member of this structure tells the system which language the shader is authored in:
      SHADER_SOURCE_LANGUAGE_DEFAULT - The shader source language matches the underlying graphics API: HLSL for Direct3D11/Direct3D12 mode, and GLSL for OpenGL and OpenGLES modes. SHADER_SOURCE_LANGUAGE_HLSL - The shader source is in HLSL. For OpenGL and OpenGLES modes, the source code will be converted to GLSL. SHADER_SOURCE_LANGUAGE_GLSL - The shader source is in GLSL. There is currently no GLSL to HLSL converter, so this value should only be used for OpenGL and OpenGLES modes. There are two ways to provide the shader source code. The first way is to use Source member. The second way is to provide a file path in FilePath member. Since the engine is entirely decoupled from the platform and the host file system is platform-dependent, the structure exposes pShaderSourceStreamFactory member that is intended to provide the engine access to the file system. If FilePath is provided, shader source factory must also be provided. If the shader source contains any #include directives, the source stream factory will also be used to load these files. The engine provides default implementation for every supported platform that should be sufficient in most cases. Custom implementation can be provided when needed.
      When sampling a texture in a shader, the texture sampler was traditionally specified as separate object that was bound to the pipeline at run time or set as part of the texture object itself. However, in most cases it is known beforehand what kind of sampler will be used in the shader. Next-generation APIs expose new type of sampler called static sampler that can be initialized directly in the pipeline state. Diligent Engine exposes this functionality: when creating a shader, textures can be assigned static samplers. If static sampler is assigned, it will always be used instead of the one initialized in the texture shader resource view. To initialize static samplers, prepare an array of StaticSamplerDesc structures and initialize StaticSamplers and NumStaticSamplers members. Static samplers are more efficient and it is highly recommended to use them whenever possible. On older APIs, static samplers are emulated via generic sampler objects.
      The following is an example of shader initialization:
      ShaderCreationAttribs Attrs; Attrs.Desc.Name = "MyPixelShader"; Attrs.FilePath = "MyShaderFile.fx"; Attrs.SearchDirectories = "shaders;shaders\\inc;"; Attrs.EntryPoint = "MyPixelShader"; Attrs.Desc.ShaderType = SHADER_TYPE_PIXEL; Attrs.SourceLanguage = SHADER_SOURCE_LANGUAGE_HLSL; BasicShaderSourceStreamFactory BasicSSSFactory(Attrs.SearchDirectories); Attrs.pShaderSourceStreamFactory = &BasicSSSFactory; ShaderVariableDesc ShaderVars[] = {     {"g_StaticTexture", SHADER_VARIABLE_TYPE_STATIC},     {"g_MutableTexture", SHADER_VARIABLE_TYPE_MUTABLE},     {"g_DynamicTexture", SHADER_VARIABLE_TYPE_DYNAMIC} }; Attrs.Desc.VariableDesc = ShaderVars; Attrs.Desc.NumVariables = _countof(ShaderVars); Attrs.Desc.DefaultVariableType = SHADER_VARIABLE_TYPE_STATIC; StaticSamplerDesc StaticSampler; StaticSampler.Desc.MinFilter = FILTER_TYPE_LINEAR; StaticSampler.Desc.MagFilter = FILTER_TYPE_LINEAR; StaticSampler.Desc.MipFilter = FILTER_TYPE_LINEAR; StaticSampler.TextureName = "g_MutableTexture"; Attrs.Desc.NumStaticSamplers = 1; Attrs.Desc.StaticSamplers = &StaticSampler; ShaderMacroHelper Macros; Macros.AddShaderMacro("USE_SHADOWS", 1); Macros.AddShaderMacro("NUM_SHADOW_SAMPLES", 4); Macros.Finalize(); Attrs.Macros = Macros; RefCntAutoPtr<IShader> pShader; m_pDevice->CreateShader( Attrs, &pShader );
      Creating the Pipeline State Object
      After all required shaders are created, the rest of the fields of the PipelineStateDesc structure provide depth-stencil, rasterizer, and blend state descriptions, the number and format of render targets, input layout format, etc. For instance, rasterizer state can be described as follows:
      PipelineStateDesc PSODesc; RasterizerStateDesc &RasterizerDesc = PSODesc.GraphicsPipeline.RasterizerDesc; RasterizerDesc.FillMode = FILL_MODE_SOLID; RasterizerDesc.CullMode = CULL_MODE_NONE; RasterizerDesc.FrontCounterClockwise = True; RasterizerDesc.ScissorEnable = True; RasterizerDesc.AntialiasedLineEnable = False; Depth-stencil and blend states are defined in a similar fashion.
      Another important thing that pipeline state object encompasses is the input layout description that defines how inputs to the vertex shader, which is the very first shader stage, should be read from the memory. Input layout may define several vertex streams that contain values of different formats and sizes:
      // Define input layout InputLayoutDesc &Layout = PSODesc.GraphicsPipeline.InputLayout; LayoutElement TextLayoutElems[] = {     LayoutElement( 0, 0, 3, VT_FLOAT32, False ),     LayoutElement( 1, 0, 4, VT_UINT8, True ),     LayoutElement( 2, 0, 2, VT_FLOAT32, False ), }; Layout.LayoutElements = TextLayoutElems; Layout.NumElements = _countof( TextLayoutElems ); Finally, pipeline state defines primitive topology type. When all required members are initialized, a pipeline state object can be created by IRenderDevice::CreatePipelineState() method:
      // Define shader and primitive topology PSODesc.GraphicsPipeline.PrimitiveTopologyType = PRIMITIVE_TOPOLOGY_TYPE_TRIANGLE; PSODesc.GraphicsPipeline.pVS = pVertexShader; PSODesc.GraphicsPipeline.pPS = pPixelShader; PSODesc.Name = "My pipeline state"; m_pDev->CreatePipelineState(PSODesc, &m_pPSO); When PSO object is bound to the pipeline, the engine invokes all API-specific commands to set all states specified by the object. In case of Direct3D12 this maps directly to setting the D3D12 PSO object. In case of Direct3D11, this involves setting individual state objects (such as rasterizer and blend states), shaders, input layout etc. In case of OpenGL, this requires a number of fine-grain state tweaking calls. Diligent Engine keeps track of currently bound states and only calls functions to update these states that have actually changed.
      Binding Shader Resources
      Direct3D11 and OpenGL utilize fine-grain resource binding models, where an application binds individual buffers and textures to certain shader or program resource binding slots. Direct3D12 uses a very different approach, where resource descriptors are grouped into tables, and an application can bind all resources in the table at once by setting the table in the command list. Resource binding model in Diligent Engine is designed to leverage this new method. It introduces a new object called shader resource binding that encapsulates all resource bindings required for all shaders in a certain pipeline state. It also introduces the classification of shader variables based on the frequency of expected change that helps the engine group them into tables under the hood:
      Static variables (SHADER_VARIABLE_TYPE_STATIC) are variables that are expected to be set only once. They may not be changed once a resource is bound to the variable. Such variables are intended to hold global constants such as camera attributes or global light attributes constant buffers. Mutable variables (SHADER_VARIABLE_TYPE_MUTABLE) define resources that are expected to change on a per-material frequency. Examples may include diffuse textures, normal maps etc. Dynamic variables (SHADER_VARIABLE_TYPE_DYNAMIC) are expected to change frequently and randomly. Shader variable type must be specified during shader creation by populating an array of ShaderVariableDesc structures and initializing ShaderCreationAttribs::Desc::VariableDesc and ShaderCreationAttribs::Desc::NumVariables members (see example of shader creation above).
      Static variables cannot be changed once a resource is bound to the variable. They are bound directly to the shader object. For instance, a shadow map texture is not expected to change after it is created, so it can be bound directly to the shader:
      PixelShader->GetShaderVariable( "g_tex2DShadowMap" )->Set( pShadowMapSRV ); Mutable and dynamic variables are bound via a new Shader Resource Binding object (SRB) that is created by the pipeline state (IPipelineState::CreateShaderResourceBinding()):
      m_pPSO->CreateShaderResourceBinding(&m_pSRB); Note that an SRB is only compatible with the pipeline state it was created from. SRB object inherits all static bindings from shaders in the pipeline, but is not allowed to change them.
      Mutable resources can only be set once for every instance of a shader resource binding. Such resources are intended to define specific material properties. For instance, a diffuse texture for a specific material is not expected to change once the material is defined and can be set right after the SRB object has been created:
      m_pSRB->GetVariable(SHADER_TYPE_PIXEL, "tex2DDiffuse")->Set(pDiffuseTexSRV); In some cases it is necessary to bind a new resource to a variable every time a draw command is invoked. Such variables should be labeled as dynamic, which will allow setting them multiple times through the same SRB object:
      m_pSRB->GetVariable(SHADER_TYPE_VERTEX, "cbRandomAttribs")->Set(pRandomAttrsCB); Under the hood, the engine pre-allocates descriptor tables for static and mutable resources when an SRB objcet is created. Space for dynamic resources is dynamically allocated at run time. Static and mutable resources are thus more efficient and should be used whenever possible.
      As you can see, Diligent Engine does not expose low-level details of how resources are bound to shader variables. One reason for this is that these details are very different for various APIs. The other reason is that using low-level binding methods is extremely error-prone: it is very easy to forget to bind some resource, or bind incorrect resource such as bind a buffer to the variable that is in fact a texture, especially during shader development when everything changes fast. Diligent Engine instead relies on shader reflection system to automatically query the list of all shader variables. Grouping variables based on three types mentioned above allows the engine to create optimized layout and take heavy lifting of matching resources to API-specific resource location, register or descriptor in the table.
      This post gives more details about the resource binding model in Diligent Engine.
      Setting the Pipeline State and Committing Shader Resources
      Before any draw or compute command can be invoked, the pipeline state needs to be bound to the context:
      m_pContext->SetPipelineState(m_pPSO); Under the hood, the engine sets the internal PSO object in the command list or calls all the required native API functions to properly configure all pipeline stages.
      The next step is to bind all required shader resources to the GPU pipeline, which is accomplished by IDeviceContext::CommitShaderResources() method:
      m_pContext->CommitShaderResources(m_pSRB, COMMIT_SHADER_RESOURCES_FLAG_TRANSITION_RESOURCES); The method takes a pointer to the shader resource binding object and makes all resources the object holds available for the shaders. In the case of D3D12, this only requires setting appropriate descriptor tables in the command list. For older APIs, this typically requires setting all resources individually.
      Next-generation APIs require the application to track the state of every resource and explicitly inform the system about all state transitions. For instance, if a texture was used as render target before, while the next draw command is going to use it as shader resource, a transition barrier needs to be executed. Diligent Engine does the heavy lifting of state tracking.  When CommitShaderResources() method is called with COMMIT_SHADER_RESOURCES_FLAG_TRANSITION_RESOURCES flag, the engine commits and transitions resources to correct states at the same time. Note that transitioning resources does introduce some overhead. The engine tracks state of every resource and it will not issue the barrier if the state is already correct. But checking resource state is an overhead that can sometimes be avoided. The engine provides IDeviceContext::TransitionShaderResources() method that only transitions resources:
      m_pContext->TransitionShaderResources(m_pPSO, m_pSRB); In some scenarios it is more efficient to transition resources once and then only commit them.
      Invoking Draw Command
      The final step is to set states that are not part of the PSO, such as render targets, vertex and index buffers. Diligent Engine uses Direct3D11-syle API that is translated to other native API calls under the hood:
      ITextureView *pRTVs[] = {m_pRTV}; m_pContext->SetRenderTargets(_countof( pRTVs ), pRTVs, m_pDSV); // Clear render target and depth buffer const float zero[4] = {0, 0, 0, 0}; m_pContext->ClearRenderTarget(nullptr, zero); m_pContext->ClearDepthStencil(nullptr, CLEAR_DEPTH_FLAG, 1.f); // Set vertex and index buffers IBuffer *buffer[] = {m_pVertexBuffer}; Uint32 offsets[] = {0}; Uint32 strides[] = {sizeof(MyVertex)}; m_pContext->SetVertexBuffers(0, 1, buffer, strides, offsets, SET_VERTEX_BUFFERS_FLAG_RESET); m_pContext->SetIndexBuffer(m_pIndexBuffer, 0); Different native APIs use various set of function to execute draw commands depending on command details (if the command is indexed, instanced or both, what offsets in the source buffers are used etc.). For instance, there are 5 draw commands in Direct3D11 and more than 9 commands in OpenGL with something like glDrawElementsInstancedBaseVertexBaseInstance not uncommon. Diligent Engine hides all details with single IDeviceContext::Draw() method that takes takes DrawAttribs structure as an argument. The structure members define all attributes required to perform the command (primitive topology, number of vertices or indices, if draw call is indexed or not, if draw call is instanced or not, if draw call is indirect or not, etc.). For example:
      DrawAttribs attrs; attrs.IsIndexed = true; attrs.IndexType = VT_UINT16; attrs.NumIndices = 36; attrs.Topology = PRIMITIVE_TOPOLOGY_TRIANGLE_LIST; pContext->Draw(attrs); For compute commands, there is IDeviceContext::DispatchCompute() method that takes DispatchComputeAttribs structure that defines compute grid dimension.
      Source Code
      Full engine source code is available on GitHub and is free to use. The repository contains two samples, asteroids performance benchmark and example Unity project that uses Diligent Engine in native plugin.
      AntTweakBar sample is Diligent Engine’s “Hello World” example.

       
      Atmospheric scattering sample is a more advanced example. It demonstrates how Diligent Engine can be used to implement various rendering tasks: loading textures from files, using complex shaders, rendering to multiple render targets, using compute shaders and unordered access views, etc.

      Asteroids performance benchmark is based on this demo developed by Intel. It renders 50,000 unique textured asteroids and allows comparing performance of Direct3D11 and Direct3D12 implementations. Every asteroid is a combination of one of 1000 unique meshes and one of 10 unique textures.

      Finally, there is an example project that shows how Diligent Engine can be integrated with Unity.

      Future Work
      The engine is under active development. It currently supports Windows desktop, Universal Windows and Android platforms. Direct3D11, Direct3D12, OpenGL/GLES backends are now feature complete. Vulkan backend is coming next, and support for more platforms is planned.
    • By reenigne
      For those that don't know me. I am the individual who's two videos are listed here under setup for https://wiki.libsdl.org/Tutorials
      I also run grhmedia.com where I host the projects and code for the tutorials I have online.
      Recently, I received a notice from youtube they will be implementing their new policy in protecting video content as of which I won't be monetized till I meat there required number of viewers and views each month.

      Frankly, I'm pretty sick of youtube. I put up a video and someone else learns from it and puts up another video and because of the way youtube does their placement they end up with more views.
      Even guys that clearly post false information such as one individual who said GLEW 2.0 was broken because he didn't know how to compile it. He in short didn't know how to modify the script he used because he didn't understand make files and how the requirements of the compiler and library changes needed some different flags.

      At the end of the month when they implement this I will take down the content and host on my own server purely and it will be a paid system and or patreon. 

      I get my videos may be a bit dry, I generally figure people are there to learn how to do something and I rather not waste their time. 
      I used to also help people for free even those coming from the other videos. That won't be the case any more. I used to just take anyone emails and work with them my email is posted on the site.

      I don't expect to get the required number of subscribers in that time or increased views. Even if I did well it wouldn't take care of each reoccurring month.
      I figure this is simpler and I don't plan on putting some sort of exorbitant fee for a monthly subscription or the like.
      I was thinking on the lines of a few dollars 1,2, and 3 and the larger subscription gets you assistance with the content in the tutorials if needed that month.
      Maybe another fee if it is related but not directly in the content. 
      The fees would serve to cut down on the number of people who ask for help and maybe encourage some of the people to actually pay attention to what is said rather than do their own thing. That actually turns out to be 90% of the issues. I spent 6 hours helping one individual last week I must have asked him 20 times did you do exactly like I said in the video even pointed directly to the section. When he finally sent me a copy of the what he entered I knew then and there he had not. I circled it and I pointed out that wasn't what I said to do in the video. I didn't tell him what was wrong and how I knew that way he would go back and actually follow what it said to do. He then reported it worked. Yea, no kidding following directions works. But hey isn't alone and well its part of the learning process.

      So the point of this isn't to be a gripe session. I'm just looking for a bit of feed back. Do you think the fees are unreasonable?
      Should I keep the youtube channel and do just the fees with patreon or do you think locking the content to my site and require a subscription is an idea.

      I'm just looking at the fact it is unrealistic to think youtube/google will actually get stuff right or that youtube viewers will actually bother to start looking for more accurate videos. 
    • By Balma Alparisi
      i got error 1282 in my code.
      sf::ContextSettings settings; settings.majorVersion = 4; settings.minorVersion = 5; settings.attributeFlags = settings.Core; sf::Window window; window.create(sf::VideoMode(1600, 900), "Texture Unit Rectangle", sf::Style::Close, settings); window.setActive(true); window.setVerticalSyncEnabled(true); glewInit(); GLuint shaderProgram = createShaderProgram("FX/Rectangle.vss", "FX/Rectangle.fss"); float vertex[] = { -0.5f,0.5f,0.0f, 0.0f,0.0f, -0.5f,-0.5f,0.0f, 0.0f,1.0f, 0.5f,0.5f,0.0f, 1.0f,0.0f, 0.5,-0.5f,0.0f, 1.0f,1.0f, }; GLuint indices[] = { 0,1,2, 1,2,3, }; GLuint vao; glGenVertexArrays(1, &vao); glBindVertexArray(vao); GLuint vbo; glGenBuffers(1, &vbo); glBindBuffer(GL_ARRAY_BUFFER, vbo); glBufferData(GL_ARRAY_BUFFER, sizeof(vertex), vertex, GL_STATIC_DRAW); GLuint ebo; glGenBuffers(1, &ebo); glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo); glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices,GL_STATIC_DRAW); glVertexAttribPointer(0, 3, GL_FLOAT, false, sizeof(float) * 5, (void*)0); glEnableVertexAttribArray(0); glVertexAttribPointer(1, 2, GL_FLOAT, false, sizeof(float) * 5, (void*)(sizeof(float) * 3)); glEnableVertexAttribArray(1); GLuint texture[2]; glGenTextures(2, texture); glActiveTexture(GL_TEXTURE0); glBindTexture(GL_TEXTURE_2D, texture[0]); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); sf::Image* imageOne = new sf::Image; bool isImageOneLoaded = imageOne->loadFromFile("Texture/container.jpg"); if (isImageOneLoaded) { glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, imageOne->getSize().x, imageOne->getSize().y, 0, GL_RGBA, GL_UNSIGNED_BYTE, imageOne->getPixelsPtr()); glGenerateMipmap(GL_TEXTURE_2D); } delete imageOne; glActiveTexture(GL_TEXTURE1); glBindTexture(GL_TEXTURE_2D, texture[1]); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); sf::Image* imageTwo = new sf::Image; bool isImageTwoLoaded = imageTwo->loadFromFile("Texture/awesomeface.png"); if (isImageTwoLoaded) { glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, imageTwo->getSize().x, imageTwo->getSize().y, 0, GL_RGBA, GL_UNSIGNED_BYTE, imageTwo->getPixelsPtr()); glGenerateMipmap(GL_TEXTURE_2D); } delete imageTwo; glUniform1i(glGetUniformLocation(shaderProgram, "inTextureOne"), 0); glUniform1i(glGetUniformLocation(shaderProgram, "inTextureTwo"), 1); GLenum error = glGetError(); std::cout << error << std::endl; sf::Event event; bool isRunning = true; while (isRunning) { while (window.pollEvent(event)) { if (event.type == event.Closed) { isRunning = false; } } glClear(GL_COLOR_BUFFER_BIT); if (isImageOneLoaded && isImageTwoLoaded) { glActiveTexture(GL_TEXTURE0); glBindTexture(GL_TEXTURE_2D, texture[0]); glActiveTexture(GL_TEXTURE1); glBindTexture(GL_TEXTURE_2D, texture[1]); glUseProgram(shaderProgram); } glBindVertexArray(vao); glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, nullptr); glBindVertexArray(0); window.display(); } glDeleteVertexArrays(1, &vao); glDeleteBuffers(1, &vbo); glDeleteBuffers(1, &ebo); glDeleteProgram(shaderProgram); glDeleteTextures(2,texture); return 0; } and this is the vertex shader
      #version 450 core layout(location=0) in vec3 inPos; layout(location=1) in vec2 inTexCoord; out vec2 TexCoord; void main() { gl_Position=vec4(inPos,1.0); TexCoord=inTexCoord; } and the fragment shader
      #version 450 core in vec2 TexCoord; uniform sampler2D inTextureOne; uniform sampler2D inTextureTwo; out vec4 FragmentColor; void main() { FragmentColor=mix(texture(inTextureOne,TexCoord),texture(inTextureTwo,TexCoord),0.2); } I was expecting awesomeface.png on top of container.jpg

    • By khawk
      We've just released all of the source code for the NeHe OpenGL lessons on our Github page at https://github.com/gamedev-net/nehe-opengl. code - 43 total platforms, configurations, and languages are included.
      Now operated by GameDev.net, NeHe is located at http://nehe.gamedev.net where it has been a valuable resource for developers wanting to learn OpenGL and graphics programming.

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