Sign in to follow this  
stu2000

OpenGL glOrtho 2d help

Recommended Posts

stu2000    101
Hello there, I am trying to develop a webcam application thingy and would really love this to be 2d rather than 3d, with the webcam feed always taking up the screen. I have spent hours trying to get glOrtho to work for me, but my display of the webcam feed is always offscreen, or just not drawn. I have spent hours on it messing around with disabling lighting/blending etc and experimenting with loadIdentities but for the life of me cannot figure out whats wrong.

The key thing is that i have a define ' #define USE_ORTHO ' which is used to switch between 2d and 3d as I dont feel like losing everything in this process and might want to go back at some point to 3d.

I have set up a 'setuportho' function which is maybe the cause:

void SetupOrtho(int w, int h)
{
glViewport(0, 0, w, h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0.f, 2.f, 0.f, 2.f, 0.f, 100.f);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
}

and my render function is here:
void Render()
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

glLoadIdentity();//reset matrix

glColor3f(0,1,0);
glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, cameraImageTextureID);

#ifdef USE_ORTHO
glBegin(GL_QUADS);
glTexCoord2s(1,1); glVertex3f(0.1, 0.1, 0.9);
glTexCoord2s(1,0); glVertex3f(0.1, 0.9, 0.9);
glTexCoord2s(0,0); glVertex3f(0.9, 0.9, 0.9);
glTexCoord2s(0,1); glVertex3f(0.9, 0.1, 0.9);
glEnd();
#else
glBegin(GL_QUADS);
glTexCoord2s(1,1); glVertex3f(-8, -6, -10);
glTexCoord2s(1,0); glVertex3f(-8, 6, -10);
glTexCoord2s(0,0); glVertex3f(8, 6, -10);
glTexCoord2s(0,1); glVertex3f(8, -6, -10);
glEnd();
#endif

//glDeleteTextures(GL_TEXTURE_2D, &cameraImageTextureID);
//glDisable(GL_TEXTURE_2D);

glFlush();
SwapBuffers(g_HDC); //bring the back buffer to the foreground
}

but maybe the problem is burried in the rest of the code with lighting etc.

I have uploaded the entire project here: http://www.putfile2.com/f/1049/ntkdtp

for those of you who probably find it easier to work in MSVC rather than burying through this text. Hopefully you wont have issues as everything including libs are there. Done in MSVC++ 2008 express 32bit win7. People have had problems in the past figuring out how to download, hence I have got my bro to put in a MASSIVE green download button. That should help.


Here is the entire code dump, sorry its kind of long as everyhting is in one file DOH! I was hoping it wouldnt come to this and feel like a smeghead asking for help.

#include <stdio.h>
#include <stdarg.h>
#include <stdlib.h>
#include <iostream>
#include <sstream>
#include <vector>

#include <windows.h>
#include <mmsystem.h>

#include "videoInput.h"
#include <gl/gl.h>
#include <gl/glu.h>

#include <tchar.h>


#define USE_ORTHO


//////Defines
//#define BITMAP_ID 0x4D42


//Global variables

HDC g_HDC; // global device context
bool fullScreen = false; // true = fullscreen;false = windowed
bool keyPressed[256]; // holds true for keys that are pressed
bool leftMouseButton = false; // is the left mouse button pressed
bool rigthMouseButton = false; // is the right mouse button pressed.

//unsigned char * pixel_buffer_1;
//unsigned char * pixel_buffer_2;


#pragma region GLOBLE VARIABLE

int size = 921600;
int device1 = 0;

GLuint cameraImageTextureID;
int frameWidth = 640;
int frameHeight = 480;

// Create a videoInput object
videoInput VI;

unsigned char * frame = new unsigned char[size];




//-----var about control fps
static float lasttime = 0.0f; // store the last time
static float lasttime2 = 0.0f;
static float currenttime; // store the current time

#ifndef USE_ORTHO
//light variables structure and names copied (values slightly edited) from 'OpenGL Game Programming' by Kevin Hawkins and Dave Astle, 2001
float ambientLight[] = { 1.0f, 1.0f, 1.0f, 1.0f }; // ambient light
float diffuseLight[] = { 1.0f, 1.0f, 1.0f, 1.0f}; // diffuse light
float lightPosition[] = { 0.0f, 0.0f, 1000.0f, 1.0f}; // the light position

float matAmbient[] = {0.0f, 0.0f, 0.0f, 1.0f};
float matDiff[] = {1.0f, 1.0f, 1.0f, 1.0f};
//end of light variables and copied structure material
#endif

#pragma endregion

void SetupOrtho(int w, int h)
{
glViewport(0, 0, w, h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0.f, 2.f, 0.f, 2.f, 0.f, 100.f);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
}

void Render()
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

glLoadIdentity();//reset matrix

glColor3f(0,1,0);
glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, cameraImageTextureID);

#ifdef USE_ORTHO
glBegin(GL_QUADS);
glTexCoord2s(1,1); glVertex3f(0.1, 0.1, 0.9);
glTexCoord2s(1,0); glVertex3f(0.1, 0.9, 0.9);
glTexCoord2s(0,0); glVertex3f(0.9, 0.9, 0.9);
glTexCoord2s(0,1); glVertex3f(0.9, 0.1, 0.9);
glEnd();
#else
glBegin(GL_QUADS);
glTexCoord2s(1,1); glVertex3f(-8, -6, -10);
glTexCoord2s(1,0); glVertex3f(-8, 6, -10);
glTexCoord2s(0,0); glVertex3f(8, 6, -10);
glTexCoord2s(0,1); glVertex3f(8, -6, -10);
glEnd();
#endif

//glDeleteTextures(GL_TEXTURE_2D, &cameraImageTextureID);
//glDisable(GL_TEXTURE_2D);

glFlush();
SwapBuffers(g_HDC); //bring the back buffer to the foreground
}


void initGL()
{
glClearColor(0.3f,0.3f,1.0f,1.0f); //clear to blue
glFrontFace(GL_CW); //set it so that polygons are drawn clockwise (does have an affect for some reason).
glEnable(GL_TEXTURE_2D);


#ifndef USE_ORTHO
glEnable(GL_LIGHTING); //enable lighting
glEnable(GL_DEPTH_TEST); //hidden surface removal


glShadeModel(GL_SMOOTH);
glEnable(GL_BLEND);
glShadeModel(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glEnable(GL_CULL_FACE); //do not draw inside of polygons for performance
glMaterialfv(GL_FRONT, GL_AMBIENT, matAmbient);
glMaterialfv(GL_FRONT, GL_DIFFUSE, matDiff);

//LIGHTING
glLightfv(GL_LIGHT0, GL_AMBIENT, ambientLight); //set up the ambient element
glLightfv(GL_LIGHT0, GL_DIFFUSE, diffuseLight); //set up the diffuse element
glLightfv(GL_LIGHT0, GL_POSITION, lightPosition); //place the light
glEnable(GL_LIGHT0);

glEnable(GL_COLOR_MATERIAL); //-----------------PUTH THIS BACK MAYBE
glColorMaterial(GL_FRONT, GL_AMBIENT_AND_DIFFUSE);
//END OF LIGHTING

glMatrixMode(GL_PROJECTION);
gluPerspective(60,1.0f,0.1f,1000.0f); //set the perspective for 60 degree FOV witha a 1:1 aspect ratio and a close clipping pane of 0.1 and far of 1000 units.
glMatrixMode(GL_MODELVIEW);

//gluLookAt(0, 100, 100, 0,0,0,0,0,1); //important that glulookat is in the modelview matrix
#else
glDisable(GL_CULL_FACE);
glDisable(GL_LIGHTING); //enable lighting
glDisable(GL_DEPTH_TEST); //hidden surface removal
//glDisable(GL_BLEND);
glEnable(GL_BLEND);
glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
SetupOrtho(frameWidth, frameHeight);
#endif


}

void Initialize()
{
initGL();

// Get first camera frame here


//Prints out a list of available devices and returns num of devices found
int numDevices = VI.listDevices();


// If you want to capture at a different frame rate (default is 30) specify it here, you are not guaranteed to get this fps though.
VI.setIdealFramerate(0, 60);

// Setup the first device - there are a number of options:
// this could be any deviceID that shows up in listDevices
// VI.setupDevice(device1); // Setup the first device with the default settings
// VI.setupDevice(device1, VI_COMPOSITE); // or setup device with specific connection type
VI.setupDevice(device1, frameWidth, frameHeight); // or setup device with specified video size
// VI.setupDevice(device1, 320, 240, VI_COMPOSITE); // or setup device with video size and connection type
// VI.setFormat(device1, VI_NTSC_M); // if your card doesn't remember what format it should be
// call this with the appropriate format listed above
// NOTE: must be called after setupDevice!

// Optionally setup a second (or third, fourth ...) device - same options as above
// VI.setupDevice(device2);

// As requested width and height can not always be accomodated
// Make sure to check the size once the device is setup

frameWidth = VI.getWidth(device1);
frameHeight = VI.getHeight(device1);
size = VI.getSize(device1);


// pixel_buffer_1 = unsigned char[size];
// pixel_buffer_2 = unsigned char[size];

// To get the data from the device first check if the data is new
if (VI.isFrameNew(device1))
{
// VI.getPixels(device1, pixel_buffer_1, false, false); //fills pixels as a BGR (for openCV) unsigned char array - no flipping
// VI.getPixels(device1, pixel_buffer_2, true, true); //fills pixels as a RGB (for openGL) unsigned char array - flipping!
frame = VI.getPixels(device1, true, true); //fills pixels as a BGR (for openGL) unsigned char array - no flipping
}

// Same applies to device2 etc

// To get a settings dialog for the device
VI.showSettingsWindow(device1);

glGenTextures(1,&cameraImageTextureID);
glBindTexture(GL_TEXTURE_2D, cameraImageTextureID);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);


glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, frameWidth,frameHeight, 0, GL_RGB, GL_UNSIGNED_BYTE, frame);
// gluBuild2DMipmaps(GL_TEXTURE_2D, GL_RGB, frameWidth, frameHeight, GL_BGR_EXT, GL_UNSIGNED_BYTE, frame);


// Shut down devices properly
// VI.stopDevice(device1);
// VI.stopDevice(device2);
}

void Reshape(int w, int h)
{
double ww = w;
double hh = h;

#ifndef USE_ORTHO
glViewport(0, 0, w, h); /* Establish viewing area to cover entire window. */
glMatrixMode(GL_PROJECTION);
glLoadIdentity (); //replace the current matrix with the Identity Matrix
gluPerspective(60, ww/hh,0.1f,1000.0f);
glMatrixMode(GL_MODELVIEW);
#else
SetupOrtho(w, h);
#endif


}

void GameLoop()
{
// Find out how much time has passed
// static double time = timeGetTime();
// double time2 = timeGetTime();
// double timeDiff = (time2 - time) / 1000;
// time = time2;

// Sort out user input
if(keyPressed['W']){}
if(keyPressed['S']){}
if(keyPressed['A']){}
if(keyPressed['D']){}
if(keyPressed['B']){}
if(keyPressed['R']){}


// Capture frame from camera here

if (VI.isFrameNew(device1))
{
// VI.getPixels(device1, pixel_buffer_1, false, false); // fills pixels as a BGR (for openCV) unsigned char array - no flipping
// VI.getPixels(device1, pixel_buffer_2, true, true); // fills pixels as a RGB (for openGL) unsigned char array - flipping!
VI.getPixels(device1, frame, false, true);
}

// End of capture frame from camera


/*

// Clear the tracker buffer
for(unsigned int y=0; y<frameHeight; y++)
{
for(unsigned int x=0; x<frameWidth; x++)
{
trackBuffer[x][y] = 0;
}
}


// Process the image
for(unsigned int i=0; i<frameHeight; i++)
{
for(unsigned int j=0; j<frameWidth; j++)
{


}
}

// Process the tracker buffer
for(unsigned int y=0; y<frameHeight; y++)
{
for(unsigned int x=0; x<frameWidth; x++)
{
trackBuffer[x][y] == 0;
}
}

// Render the tracker buffer
for(unsigned int y=0; y<frameHeight; y++)
{
for(unsigned int x=0; x<frameWidth; x++)
{
if(trackBuffer[x][y] == 1)
{

}
}
}

*/

// End of processing the image


// Turn image into texture
glBindTexture(GL_TEXTURE_2D, cameraImageTextureID);

glGenTextures(1,&cameraImageTextureID);
glBindTexture(GL_TEXTURE_2D, cameraImageTextureID);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);

glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);

gluBuild2DMipmaps(GL_TEXTURE_2D, GL_RGB, frameWidth, frameHeight, GL_BGR_EXT, GL_UNSIGNED_BYTE, frame);
glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, frameWidth,frameHeight,GL_BGR_EXT,GL_UNSIGNED_BYTE,frame);

Render();
}


void SetupPixelFormat(HDC hDC)
{
int nPixelFormat; //our pixel format index

static PIXELFORMATDESCRIPTOR pfd = { sizeof(PIXELFORMATDESCRIPTOR), 1, PFD_DRAW_TO_WINDOW | PFD_SUPPORT_OPENGL | PFD_DOUBLEBUFFER, PFD_TYPE_RGBA, 32, 0,0,0,0,0,0,0,0,0,0,0,0,0,16,0,0,PFD_MAIN_PLANE, 0,0,0,0};
nPixelFormat = ChoosePixelFormat(hDC, &pfd); //chose matching pixel format
SetPixelFormat(hDC, nPixelFormat, &pfd); //set the pixel format to DC
}


LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
static HGLRC hRC; // rendering context
static HDC hDC; // device context
int width, height; // window width and height
int oldMouseX, oldMouseY; // old mouse coordinates

double zDeltaDifference = 0;
static short zDelta;


switch(message)
{
case WM_CREATE:
hDC = GetDC(hwnd); // get current windows device context
g_HDC = hDC;
SetupPixelFormat(hDC); // call our pixel format setup function

//create rendering context and make it current
hRC = wglCreateContext(hDC);
wglMakeCurrent(hDC, hRC);

return 0;
break;

case WM_CLOSE: // window is closing
// Deselect rendering context and delete it
wglMakeCurrent(hDC, NULL);
wglDeleteContext(hRC);

// Send WM_QUIT to message queue
PostQuitMessage(0);

return 0;
break;

case WM_SIZE:
height = HIWORD(lParam); //retrieve width and height
width = LOWORD(lParam);

if (height==0)
{
height=1;
}

// Reset the viewport to new dimensions
glViewport(0,0, width, height);

#ifndef USE_ORTHO
// Set projection matrix current matrix
glMatrixMode(GL_PROJECTION);
glLoadIdentity();

// Calculate aspect ratio of window
gluPerspective(60.0f, (GLfloat)width/(GLfloat)height, 1.0f, 5000.0f);

glMatrixMode(GL_MODELVIEW); //set the modelview matrix
glLoadIdentity(); //reset the modelview matrix
#else
SetupOrtho(width, height);
#endif
return 0;
break;

case WM_KEYDOWN: //is a key pressed?
keyPressed[wParam] = true;
// camera.MoveZ(1);
return 0;
break;

case WM_KEYUP:
keyPressed[wParam] = false;
return 0;
break;

case WM_LBUTTONDOWN:
leftMouseButton = true;
return 0;
break;

case WM_RBUTTONDOWN:
rigthMouseButton = true;
return 0;
break;

case WM_LBUTTONUP:
leftMouseButton = false;
return 0;
break;

case WM_RBUTTONUP:
rigthMouseButton = false;
return 0;
break;

case WM_MOUSEMOVE:

// Save old mouse coordinates
// oldMouseX = mouseX;
// oldMouseY = mouseY;

// Get mouse coordinates from Windows
// mouseX = LOWORD(lParam);
// mouseY = HIWORD(lParam);



// These lines limit the camera's range
// if (mouseY < 200)
{
// mouseY = 200;
}
// if (mouseY > 450)
{
// mouseY = 450;
}
if (leftMouseButton)
{
// camera.zoom += (mouseY - oldMouseY) * 0.50f;
// camera.pitch += (mouseY - oldMouseY) * 0.1f;
// camera.angle += (oldMouseX - mouseX) * 0.30f;
}

/*
if (mouseX - oldMouseX != 0)
{
mouseX - oldMouseX > 0 ? angle += 3.0f : angle -= 3.0f ;
}
*/

return 0;
break;

case WM_MOUSEWHEEL:
// zDelta = GET_WHEEL_DELTA_WPARAM(wParam);
// camera.zoom = camera.zoom - (camera.zoom/8 * zDelta/120); //camera movement is proportional, so if your further away zooming is faster.
return 0;
break;

default:
break;
}

return (DefWindowProc(hwnd, message, wParam, lParam));
}


int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nShowCmd)
{
WNDCLASSEX windowClass; // windows class
HWND hwnd; // window handle
MSG msg; // message
bool done; // flag saying when our app is complete
DWORD dwExStyle; // window extended style
DWORD dwStyle; // window style
RECT windowRect;

// Screen/display attributes
int width = 800;
int height = 600;
int bits = 32;

windowRect.left =(long)0; // set left value to 0
windowRect.right =(long)width; // set right value to requested width
windowRect.top =(long)0; // set the top value to 0
windowRect.bottom =(long)height; // set bottom value to requested height

// Fill out the windows class structure
windowClass.cbSize = sizeof(WNDCLASSEX);
windowClass.style = CS_HREDRAW | CS_VREDRAW;
windowClass.lpfnWndProc = WndProc;
windowClass.cbClsExtra = 0;
windowClass.cbWndExtra = 0;
windowClass.hInstance = hInstance;
windowClass.hIcon = LoadIcon(NULL, IDI_APPLICATION);
windowClass.hCursor = LoadCursor(NULL, IDC_ARROW);
windowClass.hbrBackground = NULL;
windowClass.lpszMenuName = NULL;
windowClass.lpszClassName = L"MyClass";
windowClass.hIconSm = LoadIcon(NULL, IDI_WINLOGO);

// Register the windows class
if (!RegisterClassEx(&windowClass))
return 0;

if (fullScreen) //full screen
{
DEVMODE dmScreenSettings; //device mode
memset(&dmScreenSettings, 0, sizeof(dmScreenSettings));
dmScreenSettings.dmSize = sizeof(dmScreenSettings);
dmScreenSettings.dmPelsWidth = width; //screen width
dmScreenSettings.dmPelsHeight = height; //screen height
dmScreenSettings.dmBitsPerPel = bits;
dmScreenSettings.dmFields=DM_BITSPERPEL | DM_PELSWIDTH | DM_PANNINGHEIGHT;

if(ChangeDisplaySettings(&dmScreenSettings, CDS_FULLSCREEN) != DISP_CHANGE_SUCCESSFUL)
{
// Setting display mode failed, switch to windowed
MessageBox(NULL, L"Display mode failed", NULL, MB_OK);
fullScreen=FALSE;
}
}

if (fullScreen) //are we still in full screen mode
{
dwExStyle=WS_EX_APPWINDOW; //window extended style
dwStyle=WS_POPUP; //window style
ShowCursor(FALSE); //hide mouse pointer
}
else
{
dwExStyle=WS_EX_APPWINDOW | WS_EX_WINDOWEDGE; //window exteded style
dwStyle=WS_OVERLAPPEDWINDOW; //window style
}

AdjustWindowRectEx(&windowRect, dwStyle, FALSE, dwExStyle);

// Class registered so now create our window
hwnd = CreateWindowEx(NULL, L"MyClass", L"Stuart Page's Physics Game", dwStyle | WS_CLIPCHILDREN | WS_CLIPSIBLINGS, 0,0, windowRect.right - windowRect.left, windowRect.bottom - windowRect.top, NULL, NULL, hInstance, NULL);

// Check if window creation failed (hwnd would equal NULL)
if(!hwnd)
return 0;

ShowWindow(hwnd, SW_SHOW); //display the window
UpdateWindow(hwnd); //update the window

done = false; //initialize the loop condition variable

// Main message loop
Initialize();

while (!done)
{
if(PeekMessage(&msg, hwnd, NULL, NULL, PM_REMOVE)!=0) //there is a new message in the que
{
if(msg.message == WM_QUIT) //do we recieve a WM_QUIT message?
{
done = true;
}
else
{
//GAME LOOP HERE
GameLoop();
TranslateMessage(&msg);
DispatchMessage(&msg);
}

}
else //there are no new messages, so dont handle any
{
GameLoop();
}
}

if (fullScreen)
{
ChangeDisplaySettings(NULL, 0); //if so switch back to the desktop
ShowCursor(TRUE);
}
return msg.wParam;

}

Share this post


Link to post
Share on other sites
karwosts    840
[quote]
glOrtho(0.f, 2.f, 0.f, 2.f, 0.f, 100.f);

glTexCoord2s(1,1); glVertex3f(0.1, 0.1, 0.9);
glTexCoord2s(1,0); glVertex3f(0.1, 0.9, 0.9);
glTexCoord2s(0,0); glVertex3f(0.9, 0.9, 0.9);
glTexCoord2s(0,1); glVertex3f(0.9, 0.1, 0.9);
[/quote]

Can you try changing these z coordinates to -0.9, instead of +0.9? When calling glOrtho, the final 2 values are the zNear and zFar values. However the default camera in openGL looks down the negative z axis, so with this glOrtho command you'll be viewing coordinates in the box from (0,0,0) to (2,2,-100). This puts your quad right behind the camera.

Alternatively, you could leave the z coordinate at +0.9, and change the zFar plane to -100, which should have the same effect.

Share this post


Link to post
Share on other sites
stu2000    101
by the way can someone look at this bit of code in there:


// Turn image into texture
glBindTexture(GL_TEXTURE_2D, cameraImageTextureID);

glGenTextures(1,&cameraImageTextureID);
glBindTexture(GL_TEXTURE_2D, cameraImageTextureID);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);

glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);

gluBuild2DMipmaps(GL_TEXTURE_2D, GL_RGB, frameWidth, frameHeight, GL_BGR_EXT, GL_UNSIGNED_BYTE, frame);
glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, frameWidth,frameHeight,GL_BGR_EXT,GL_UNSIGNED_BYTE,frame);

It looks like im creating a texture based on webcam inpu each frame.
Is it possible and faster to just edit the texture from last frame rather than go through the whole process again?

Would this be better/same or could be improved upon?:

static bool generatedTexture = false;

if (!generatedTexture)
{
// Turn image into texture
glBindTexture(GL_TEXTURE_2D, cameraImageTextureID);

glGenTextures(1,&cameraImageTextureID);
glBindTexture(GL_TEXTURE_2D, cameraImageTextureID);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);

glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);

gluBuild2DMipmaps(GL_TEXTURE_2D, GL_RGB, frameWidth, frameHeight, GL_BGR_EXT, GL_UNSIGNED_BYTE, frame);
glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, frameWidth,frameHeight,GL_BGR_EXT,GL_UNSIGNED_BYTE,frame);
generatedTexture = true;
}
else
{
gluBuild2DMipmaps(GL_TEXTURE_2D, GL_RGB, frameWidth, frameHeight, GL_BGR_EXT, GL_UNSIGNED_BYTE, frame);
glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, frameWidth,frameHeight,GL_BGR_EXT,GL_UNSIGNED_BYTE,frame);
}

Stu

Share this post


Link to post
Share on other sites
karwosts    840
Yeah, I would say your second set of code is much preferable, though it has a few issues. I would clean it up like so:


[code]
//during constructor:
cameraImageTextureID = 0;
//

//during render loop:
//if (!generatedTexture) //don't need another variable, can use the ID to tell if its initialized or not
if(!cameraImageTextureID){

//this is bad, and probably generates an error. You can't bind the ID before the texture ID has been generated
//glBindTexture(GL_TEXTURE_2D, cameraImageTextureID);

glGenTextures(1,&cameraImageTextureID);
glBindTexture(GL_TEXTURE_2D, cameraImageTextureID);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

//You need to decide if you want to use mipmaps or not. You're generating mipmaps
//everytime you load textures, but you're disabling using them here. If you want
//mipmaps, enable them in the minification filter. If you don't, then don't waste
//processing time by generating them each frame.

//glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST_MIPMAP_LINEAR);

glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);

//when you first create the texture, just call glTexImage2D with '0' for the data,
//this initializes the texture with the parameters you set but does not fill it with data.
//then call glTexSubImage when you want to overwrite the pixels each frame
glTexImage2D(GL_TEXTURE_2D, 0, 0, 0, frameWidth,frameHeight,GL_BGR_EXT,GL_UNSIGNED_BYTE,0);

//gluBuild2DMipmaps(GL_TEXTURE_2D, GL_RGB, frameWidth, frameHeight, GL_BGR_EXT, GL_UNSIGNED_BYTE, frame);
//glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, frameWidth,frameHeight,GL_BGR_EXT,GL_UNSIGNED_BYTE,frame);
//generatedTexture = true; //dont need this
} else {
glBindTexture(GL_TEXTURE_2D, cameraImageTextureID);
}


//If you want mipmaps, you should call it AFTER you load the texture data, not before
//gluBuild2DMipmaps(GL_TEXTURE_2D, GL_RGB, frameWidth, frameHeight, GL_BGR_EXT, GL_UNSIGNED_BYTE, frame);
glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, frameWidth,frameHeight,GL_BGR_EXT,GL_UNSIGNED_BYTE,frame);
//gluBuild2DMipmaps(GL_TEXTURE_2D, GL_RGB, frameWidth, frameHeight, GL_BGR_EXT, GL_UNSIGNED_BYTE, frame);
//I think this is preferrable to the glu routine as it utilizes
//the GPU to generate mipmaps, so it should be faster. Can
//probably use either one you want.
glGenerateMipmap(GL_TEXTURE_2D);

//good practice to check for errors when generating new code
int err = glGetError();
if(err){
throw (something);
}


[/code]

Share this post


Link to post
Share on other sites
NumberXaero    2624
The fastest way would be to render to a texture, take a look at framebuffer objects, draw buffers, and texture rectangle extensions, avoid the copy altogether and just render to a texture then display it.

Share this post


Link to post
Share on other sites
karwosts    840
[quote name='NumberXaero' timestamp='1302991852' post='4799273']
The fastest way would be to render to a texture, take a look at framebuffer objects, draw buffers, and texture rectangle extensions, avoid the copy altogether and just render to a texture then display it.
[/quote]

I think hes drawing some webcam data which is probably presented to him as an array of pixels. If you're actually rendering something then it makes more sense to draw it into a framebuffer, but I think his approach is fine for presenting data from a source outside the program.

Share this post


Link to post
Share on other sites
stu2000    101
Thanks for the help - especially that long post from karwost with the comments explaining why each thing was bad and what should be done. I had always thought you needed to use mipmaps if you were going to apply a texture to something that wasnt the same size as the image you were passing in? TBH i only care about speed and not looks as I am doing this for objet recognition/tracking and not for a skype video call type thing. Once i have messed around with the example stuff you have given me I will get back to you .
Thanks again you guys are awesome!

Share this post


Link to post
Share on other sites
stu2000    101
Dont want to sound like a little girl but...

Omg thank you, thank you, thank you. I put in your code and got rid of all mipmaps. The thing now runs SUPER fast at 960 x 720 resolution. Its running even faster than it was at 640 x 480 before. I tried not using mipmaps before but must have done something wrong as it would not render but does now. This is so much better than what i thought was possible. Now I can just focus on the tracking part of the project thanks!

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Sign in to follow this  

  • Similar Content

    • By pseudomarvin
      I assumed that if a shader is computationally expensive then the execution is just slower. But running the following GLSL FS instead just crashes
      void main() { float x = 0; float y = 0; int sum = 0; for (float x = 0; x < 10; x += 0.00005) { for (float y = 0; y < 10; y += 0.00005) { sum++; } } fragColor = vec4(1, 1, 1 , 1.0); } with unhandled exception in nvoglv32.dll. Are there any hard limits on the number of steps/time that a shader can take before it is shut down? I was thinking about implementing some time intensive computation in shaders where it would take on the order of seconds to compute a frame, is that possible? Thanks.
    • By Arulbabu Donbosco
      There are studios selling applications which is just copying any 3Dgraphic content and regenerating into another new window. especially for CAVE Virtual reality experience. so that the user opens REvite or CAD or any other 3D applications and opens a model. then when the user selects the rendered window the VR application copies the 3D model information from the OpenGL window. 
      I got the clue that the VR application replaces the windows opengl32.dll file. how this is possible ... how can we copy the 3d content from the current OpenGL window.
      anyone, please help me .. how to go further... to create an application like VR CAVE. 
       
      Thanks
    • By cebugdev
      hi all,

      i am trying to build an OpenGL 2D GUI system, (yeah yeah, i know i should not be re inventing the wheel, but this is for educational and some other purpose only),
      i have built GUI system before using 2D systems such as that of HTML/JS canvas, but in 2D system, i can directly match a mouse coordinates to the actual graphic coordinates with additional computation for screen size/ratio/scale ofcourse.
      now i want to port it to OpenGL, i know that to render a 2D object in OpenGL we specify coordiantes in Clip space or use the orthographic projection, now heres what i need help about.
      1. what is the right way of rendering the GUI? is it thru drawing in clip space or switching to ortho projection?
      2. from screen coordinates (top left is 0,0 nd bottom right is width height), how can i map the mouse coordinates to OpenGL 2D so that mouse events such as button click works? In consideration ofcourse to the current screen/size dimension.
      3. when let say if the screen size/dimension is different, how to handle this? in my previous javascript 2D engine using canvas, i just have my working coordinates and then just perform the bitblk or copying my working canvas to screen canvas and scale the mouse coordinates from there, in OpenGL how to work on a multiple screen sizes (more like an OpenGL ES question).
      lastly, if you guys know any books, resources, links or tutorials that handle or discuss this, i found one with marekknows opengl game engine website but its not free,
      Just let me know. Did not have any luck finding resource in google for writing our own OpenGL GUI framework.
      IF there are no any available online, just let me know, what things do i need to look into for OpenGL and i will study them one by one to make it work.
      thank you, and looking forward to positive replies.
    • By fllwr0491
      I have a few beginner questions about tesselation that I really have no clue.
      The opengl wiki doesn't seem to talk anything about the details.
       
      What is the relationship between TCS layout out and TES layout in?
      How does the tesselator know how control points are organized?
          e.g. If TES input requests triangles, but TCS can output N vertices.
             What happens in this case?
      In this article,
      http://www.informit.com/articles/article.aspx?p=2120983
      the isoline example TCS out=4, but TES in=isoline.
      And gl_TessCoord is only a single one.
      So which ones are the control points?
      How are tesselator building primitives?
    • By Orella
      I've been developing a 2D Engine using SFML + ImGui.
      Here you can see an image
      The editor is rendered using ImGui and the scene window is a sf::RenderTexture where I draw the GameObjects and then is converted to ImGui::Image to render it in the editor.
      Now I need to create a 3D Engine during this year in my Bachelor Degree but using SDL2 + ImGui and I want to recreate what I did with the 2D Engine. 
      I've managed to render the editor like I did in the 2D Engine using this example that comes with ImGui. 
      3D Editor preview
      But I don't know how to create an equivalent of sf::RenderTexture in SDL2, so I can draw the 3D scene there and convert it to ImGui::Image to show it in the editor.
      If you can provide code will be better. And if you want me to provide any specific code tell me.
      Thanks!
  • Popular Now