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OpenGL Using SDL_TTF with OpenGL - halves my framerate

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Hi, I'm using a modified version of C-Junkie's code (from here: http://www.gamedev.net/community/forums/topic.asp?topic_id=284259) to render text from SDL_TTF to an OpenGl quad.
void SDL_GL_RenderText(string Text, TTF_Font *Font, SDL_Color Colour, SDL_Rect *Position)
{
	SDL_Surface *Initial;
	SDL_Surface *Intermediary;
	SDL_Rect Rect;
	int Width, Height;
	GLuint Texture;

	//Cast the string as a non-const char*
	char *Text_NonConst = const_cast<char*>(Text.c_str());

	//Enable blending
	glEnable(GL_BLEND);
	
	//Render text to SDL surface
	Initial = TTF_RenderText_Blended(Font, Text_NonConst, Colour);
	
	//Get the width and height of the SDL surface containing the text
	Width = nextpoweroftwo(Initial->w);
	Height = nextpoweroftwo(Initial->h);
	
	//Create a surface with useable format for OpenGL
	Intermediary = SDL_CreateRGBSurface(0, Width, Height, 32, 0x00ff0000, 0x0000ff00, 0x000000ff, 0xff000000);

	//Blit the text surface onto the OpenGL compliant one
	SDL_BlitSurface(Initial, 0, Intermediary, 0);
	
	//Setup the texture
	glGenTextures(1, &Texture);
	glBindTexture(GL_TEXTURE_2D, Texture);

	//Copy SDL surface to the OpenGL texture
	glTexImage2D(GL_TEXTURE_2D, 0, 4, Width, Height, 0, GL_BGRA, GL_UNSIGNED_BYTE, Intermediary->pixels );
	
	//Setup texture filter
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

	//Enable textures
	glEnable(GL_TEXTURE_2D);

	//Set the colour to white (for correct blending)
	glColor3f(1.0f, 1.0f, 1.0f);
	
	//Draw texture using a quad
	glBegin(GL_QUADS);

		glTexCoord2f(0.0f, 0.0f); glVertex2f(Position->x, Position->y);
		glTexCoord2f(1.0f, 0.0f); glVertex2f(Position->x + Width, Position->y);
		glTexCoord2f(1.0f, 1.0f); glVertex2f(Position->x + Width, Position->y + Height);
		glTexCoord2f(0.0f, 1.0f); glVertex2f(Position->x, Position->y + Height);

	glEnd();

	//Disable blending
	glDisable(GL_BLEND);
	
	//Clean up
	SDL_FreeSurface(Initial);
	SDL_FreeSurface(Intermediary);
	glDeleteTextures(1, &Texture);
}



Simply rendering a single word halves my framerate. Is there a way to reduce the amount of code used? Or a simpler way to copy an SDL surface to an OpenGL texture? I don't want to change my font library to something else, I like SDL_TTF for its simplicity and cross-platform capability. Thanks

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When you say it halves your framerate, are you comparing doing nothing at all versus just rendering text? Because if so, that would not be a good comparison.

One big way to speed the code up would be to save the OpenGL textures you create and simply reuse them. This of course would require you to use static text though.

If you want to use dynamic text, you could render the entire alphabet to a texture in the manner you have, and using texture coordinates, write a message one letter at a time. That would be harder to code though.

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As the poster before me pointed out dont compare to rendering nothing at all because that's not a good baseline.

With regards performance .. This is the slowest performing code you could possibly write and I dont mean that in a bad way, just as constructive criticism. It is by understanding why the code is slow that you can speed it up.

#1. You are rendering using immediate mode gl draw calls. Very slow, so read up on how to use vertex arrays or even better vertex buffer objects if you want the ultimate performance.

#2. You are rendering using quads. Although the gl vendor will convert the quads to triangles somewhere down the pipeline, the fastest data to send is indexed triangles to take advantage of the vertex cache on the gpu. Make your quads 2 indexed triangles each (tip: your triangle indices will ALWAYS be the same).

#3. You are generating a fresh texture every single frame. Big nono. Uploading data to the gpu is SLOW, so where possible generate the texture once and reuse. You should pack all your font characters (glyphs) into a single texture and bind it for the draw call, then use texture coordinates to map a characters onto a quad.

#4. Try to avoid memory allocations in your rendering loop. Memory allocation / deallocation is very slow.

Hope these tips help, and good luck with your code!

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Quote:
Original post by Simian Man
When you say it halves your framerate, are you comparing doing nothing at all versus just rendering text? Because if so, that would not be a good comparison.


Well, it's rendering a grid and a few 3D models. Maybe I'm jumping the gun a bit then.

Quote:
Original post by Simian Man
One big way to speed the code up would be to save the OpenGL textures you create and simply reuse them. This of course would require you to use static text though.


I'm using the text to show the FPS and some debug info, as well as putting it into good use on a quake-style console, so I wouldn't find use for static text.

Quote:
Original post by Simian Man
If you want to use dynamic text, you could render the entire alphabet to a texture in the manner you have, and using texture coordinates, write a message one letter at a time. That would be harder to code though.


I can't see much benefits over using bitmapped fonts in this instance.


Thanks for your response, I think I'm rendering too few things on the screen to give an accurate result.

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Quote:
Original post by TheGilb
As the poster before me pointed out dont compare to rendering nothing at all because that's not a good baseline.

With regards performance .. This is the slowest performing code you could possibly write and I dont mean that in a bad way, just as constructive criticism. It is by understanding why the code is slow that you can speed it up.

#1. You are rendering using immediate mode gl draw calls. Very slow, so read up on how to use vertex arrays or even better vertex buffer objects if you want the ultimate performance.

#2. You are rendering using quads. Although the gl vendor will convert the quads to triangles somewhere down the pipeline, the fastest data to send is indexed triangles to take advantage of the vertex cache on the gpu. Make your quads 2 indexed triangles each (tip: your triangle indices will ALWAYS be the same).

#3. You are generating a fresh texture every single frame. Big nono. Uploading data to the gpu is SLOW, so where possible generate the texture once and reuse. You should pack all your font characters (glyphs) into a single texture and bind it for the draw call, then use texture coordinates to map a characters onto a quad.

#4. Try to avoid memory allocations in your rendering loop. Memory allocation / deallocation is very slow.

Hope these tips help, and good luck with your code!


Thanks for the reply.

The code isn't mine, it was taken from the above thread and slightly modified to include STL::String support.

I thought about using a vertex array, but I thought a single quad wouldn't be THAT much of a slow-down, and a vertex array wouldn't be worth the hassle. Am I wrong?

I'll try and remove as much memory allocation I can from the code (maybe make a class, and call glGenTextures once), and use a bitmapped font solution only as a last resort, since I am fond of this method dispite these drawbacks.

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That code is horrible.

Take a good hard look at what it's doing and you'll throw it away without a thought.

For single frame, it takes a font and renders it.
Then it creates a texture. Every frame!
And finally renders the texture to a quad. and deletes the texture.

EVERY FRAME! :)

I'd suggest taking a look at Nehe's font tutorial, it's about 10000 times faster than this. Granted, his example is windows specific, but it's possible to make it multiplatform if you need to.

http://nehe.gamedev.net/data/lessons/lesson.asp?lesson=13
I think it's this one. It actually does load fonts from normal font files, not textures.

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Quote:
Original post by TheGilb
#1. You are rendering using immediate mode gl draw calls. Very slow, so read up on how to use vertex arrays or even better vertex buffer objects if you want the ultimate performance.

#2. You are rendering using quads. Although the gl vendor will convert the quads to triangles somewhere down the pipeline, the fastest data to send is indexed triangles to take advantage of the vertex cache on the gpu. Make your quads 2 indexed triangles each (tip: your triangle indices will ALWAYS be the same).

#4. Try to avoid memory allocations in your rendering loop. Memory allocation / deallocation is very slow.


These three are *nothing* compared with your #3 (sending a new texture the video card each frame). Until that is optimized, using triangles or vertex arrays would be meaningless.

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Quote:
Original post by deadstar
I'm using the text to show the FPS and some debug info, as well as putting it into good use on a quake-style console, so I wouldn't find use for static text.

Well, unless you're updating all of the text every single frame, then you can still take advantage of the static text concept. I started out with similar horribly inefficient code and it would drop my framerate to the teens or lower when I had my console on screen (maybe a dozen or two lines of text). I updated the code to cache text textures that don't change from frame to frame and now it runs much more acceptably.

Here's my new version of the function (there's plenty of room for improvement, but it didn't require any huge changes and it works well enough for me). Note that it's integrated into my GUI class so each widget automatically keeps track of the previous string it rendered and the current string, which are the first two parameters (if they match then it just reuses the texture), and it also requires that you manage the OpenGL texture outside of the function. There's some other classes referenced in there too but you can probably figure out what's going on.

void GUI::RenderText(string str, string oldstr, int x, int y, int justify, TTF_Font *font, GLuint tex, float scale, bool shadow)
{
SDL_Surface *text;

if (str.length() == 0 || !TTF_WasInit())
return;
SDL_Color col;
col.r = 255;
col.g = 255;
col.b = 255;

SDL_Surface *t = TTF_RenderText_Solid(font, str.c_str(), col);
if (!t) // Had some problems with sdl-ttf at one point
{ // At least this way it won't segfault
cout << "Error rendering text: " << str << endl;
exit(-1);
}
int neww = PowerOf2(t->w);
int newh = PowerOf2(t->h);

texman->texhand->BindTexture(tex);

if (oldstr != str)
{
Uint32 rmask, gmask, bmask, amask;
#if SDL_BYTEORDER == SDL_BIG_ENDIAN
rmask = 0xff000000;
gmask = 0x00ff0000;
bmask = 0x0000ff00;
amask = 0x000000ff;
#else
rmask = 0x000000ff;
gmask = 0x0000ff00;
bmask = 0x00ff0000;
amask = 0xff000000;
#endif
text = SDL_CreateRGBSurface(SDL_SWSURFACE, neww, newh, 32,
rmask, gmask, bmask, amask);


SDL_BlitSurface(t, NULL, text, NULL);

SDL_LockSurface(text);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, text->w, text->h, 0, GL_RGBA, GL_UNSIGNED_BYTE, text->pixels);
}

float texwidth = (float)t->w / (float)neww;
float texheight = (float)t->h / (float)newh;

int offset = 2;
int shadowpass = shadow ? 1 : 0;
while (shadowpass >= 0)
{
if (shadow)
{
if (shadowpass)
{
glColor4f(0, 0, 0, 1);
x += offset;
y += offset;
}
else
{
glColor4f(1, 1, 1, 1);
x -= offset;
y -= offset;
}
}
glBegin(GL_TRIANGLE_STRIP);
if (justify == 0)
{
glTexCoord2f(0, 0);
glVertex2f(x, y);
glTexCoord2f(0, texheight);
glVertex2f(x, y + t->h * scale);
glTexCoord2f(texwidth, 0);
glVertex2f(x + t->w * scale, y);
glTexCoord2f(texwidth, texheight);
glVertex2f(x + t->w * scale, y + t->h * scale);
}
else if (justify == 1)
{
glTexCoord2f(0, 0);
glVertex2f(x - t->w, y);
glTexCoord2f(0, texheight);
glVertex2f(x - t->w, y + t->h);
glTexCoord2f(texwidth, 0);
glVertex2f(x, y);
glTexCoord2f(texwidth, texheight);
glVertex2f(x, y + t->h);
}
glEnd();
--shadowpass;
}
glColor4f(1, 1, 1, 1);

SDL_FreeSurface(t);
if (oldstr != str)
SDL_FreeSurface(text);
}

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What I would do if you want to use SDL for font rendering, is use the same method nehe uses. It creates a quad for every character and stores every quad in a display list. It then uses a really clever way of calling these display lists. This way you can have text that updates every frame and still not really affect your framerate. I think it's by far the best solution.

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The easiest way to increase the speed of your code is to:
1. Create the openGL texture just once (pick the maximum size you need/can afford)
2. Use glTexSubImage2D instead of glTexImage2D to update the texture when the text changes

If you have multiple text targets (like a Quake-style console plus a HUD), use multiple target textures.

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Thanks everyone.

The common vote seems to be making use of NeHe's font tutorials.

I'm having trouble finding cross platform alternatives to wglUseFontBitmaps or wglUseFontOutlines. MacOSX seems to have aglUseFontBitmaps with the use of an extra library, and X11's implementation seems completely different.

In the meantime, I've dug into the SDL_TTF headers and found useful functions such as TTF_RenderGlyph, I might sit down and write a custom function to extract each glyph into a texture. I also didn't know you could do a FOR loop using chars:


for ( i = ' '; i <= '~'; i++ )
{

}



Found at www.objectmix.com. Could come in handy unless someone can pick out any disadvantages.

So I have one question remaining - I plan to create a vector of GLuints to hold every glyph, how could I reference those glyphs by char?

Making a struct containing a GLuint and a char, then looping through every glyph until the char is found seems a little expensive, and inconsistent, to me. Quick for a's and b's, slow for Y's and Z's :(

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There are tools that exist to preprocess the font into a suitable format to load as a texture so you don't need to do so at runtime. For example, BMFont.

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Quote:
Original post by deadstarSo I have one question remaining - I plan to create a vector of GLuints to hold every glyph, how could I reference those glyphs by char?

If you end up doing this rather than using SiCrane or sigsegv42's links, you can index a vector by the value of the character. Iterate over the characters and insert them into the vector, then when you need to look one up just go to index int(chartofind - 'a') (replace 'a' with whatever the first character you put in the vector was) and that should get you the character you're looking for.

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Quote:
Original post by nemebean
Quote:
Original post by deadstarSo I have one question remaining - I plan to create a vector of GLuints to hold every glyph, how could I reference those glyphs by char?

If you end up doing this rather than using SiCrane or sigsegv42's links, you can index a vector by the value of the character. Iterate over the characters and insert them into the vector, then when you need to look one up just go to index int(chartofind - 'a') (replace 'a' with whatever the first character you put in the vector was) and that should get you the character you're looking for.


Thanks, that makes sense.

The only reason I'm not using the above two methods is that they are purely Bitmap font methods (creating a bitmap font image first using an external tool, then loading into the program).

My implementation needs to directly support TTF, and the interface to be as simple as Font.LoadTTF("arial.ttf") then Font.RenderText("Hello", x, y).

I've got as far as loading the TTF file and creating all the glyphs, I'm just starting work on the rendering now.

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Well I finally got somewhere, and it's given me an UNBELIEVABLE speed increase!

I can't believe rendering "Hello" with my old code was so damn slow.

Problem is, the text looks pretty ugly, and very inconsistent. Here's a screenshot rendering Arial 28pt:



And some source:


namespace SYM
{
SYM_FONT::SYM_FONT()
{
//Set default colour
Colour.r = 255;
Colour.g = 255;
Colour.b = 255;
Colour.unused = 255;
}

bool SYM_FONT::LoadFont(string TTF_Filename, int Size)
{
//Load the font
Font = TTF_OpenFont(TTF_Filename.c_str(), Size);

//Check font loaded
if (Font == NULL)
{
//Return
return false;
}

//Get font attributes
Ascent = TTF_FontAscent(Font);
Descent = TTF_FontDescent(Font);
Height = TTF_FontHeight(Font);
LineSkip = TTF_FontLineSkip(Font);

//Loop through all chars
for (int i = 0; i <= 255; i++)
{
//Clear the surface
TempSurface = NULL;

//Render the glyph onto the SDL surface
TempSurface = TTF_RenderGlyph_Blended(Font, i, Colour);

//Check the glyph rendered
if ( TempSurface == NULL )
{
//Close the font
TTF_CloseFont(Font);

//Return
return false;
}

//New temp glyph
TempGlyph = new SYM_GLYPH;

//Get the glyph attributes
TTF_GlyphMetrics(Font, i, &TempGlyph->MinX, &TempGlyph->MaxX, &TempGlyph->MinY, &TempGlyph->MaxY, &TempGlyph->Advance);

//Convert SDL surface into OpenGL GLuint texture
TempGlyph->Texture = SDL_Surface_To_GL_Tex(TempSurface);

//Push back to glyphs vector
Glyphs.push_back(*TempGlyph);

//Delete temp glyph
delete TempGlyph;

//Free surface
SDL_FreeSurface(TempSurface);
}

//Close the font
TTF_CloseFont(Font);

return true;
}

void SYM_FONT::RenderText(string Text, float x, float y)
{
int TexMinX, TexMaxX, TexMinY, TexMaxY, Width, Height, CharID;

//Enable OpenGL texture mapping
glEnable(GL_TEXTURE_2D);

//Enable blending
glEnable(GL_BLEND);

//Loop through characters
for (int i = 0; i < Text.size(); i++)
{
//Get ID of current char
CharID = (int)Text;

Width = Glyphs[CharID].MaxX;
Height = Glyphs[CharID].MaxY;

//Bind the glyph texture
glBindTexture(GL_TEXTURE_2D, Glyphs[CharID].Texture);

//Set the colour to white (for correct blending)
glColor3f(1.0f, 1.0f, 1.0f);

//Draw the glyph
glBegin(GL_QUADS);
glTexCoord2f(0, 0); glVertex2f(x, y );
glTexCoord2f(1, 0); glVertex2f(x + Width, y );
glTexCoord2f(1, 1); glVertex2f(x + Width, y + Height);
glTexCoord2f(0, 1); glVertex2f(x, y + Height);
glEnd();

x += Glyphs[CharID].Advance;
}

//Disable blending
glDisable(GL_BLEND);

//Disable texture mapping
glDisable(GL_TEXTURE_2D);
}

GLuint SDL_Surface_To_GL_Tex(SDL_Surface *Surface)
{
GLuint Texture;
int Width, Height;
SDL_Surface *Image;
SDL_Rect Area;

//Get the dimentions of the surface
Area.x = 0;
Area.y = 0;
Area.w = Surface->w;
Area.h = Surface->h;

//Make sure the width and height are powers of two
Width = NextPowerOfTwo(Surface->w);
Height = NextPowerOfTwo(Surface->h);

//Create an OpenGL compliant surface
Image = SDL_CreateRGBSurface(SDL_SWSURFACE, Width, Height, 32, 0x00ff0000, 0x0000ff00, 0x000000ff, 0xff000000);

//Copy the surface to the OpenGL compatible one
SDL_BlitSurface(Surface, &Area, Image, &Area);

//Generate an OpenGL texture
glGenTextures(1, &Texture);

//Bind the texture ready for use
glBindTexture(GL_TEXTURE_2D, Texture);

//Copy data from the SDL surface to the OpenGL texture
glTexImage2D(GL_TEXTURE_2D, 0, 4, Width, Height, 0, GL_RGBA, GL_UNSIGNED_BYTE, Image->pixels);

//Set texture filtering
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);

//Free the SDL surface
SDL_FreeSurface(Image);

//Return the texture
return Texture;
}

} //Namespace



I can't pick out the fault. I've tried other texture filters to take off the slight 'blur' too, but to no avail.

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Glancing over your screenshot and your code, I think your problem is that you're populating the Glyph.MaxX and Y values with TTF_GlyphMetrics and using that for rendering when the texture is actually NextPowerOf2 in size, and you need to render a quad with that power of 2 size in order for the glyph to end up at the right size. I suspect that the reason your characters are different sizes is that some of them fall just to one side of a power of two and others fall just on the other side, so some end up very close to the right size and others end up half height or width.

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I was hoping you hadn't.. but you had... a texture per Glyph is just such a bad bad idea, both speed (texture switching) and resources wise (lots of small textures takes up more space than one larger one).

For the record, I developed a font renderer based on FT2 which used texture updating (instead of destorying and recreating the texture was just updated) and Glyph caching which hardly touched the framerate in the slighest, so it's possible.

That said, currently I'm prefering to use the font generator at Anglecode which SiCrane linked to.

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Quote:
Original post by nemebean
Glancing over your screenshot and your code, I think your problem is that you're populating the Glyph.MaxX and Y values with TTF_GlyphMetrics and using that for rendering when the texture is actually NextPowerOf2 in size, and you need to render a quad with that power of 2 size in order for the glyph to end up at the right size. I suspect that the reason your characters are different sizes is that some of them fall just to one side of a power of two and others fall just on the other side, so some end up very close to the right size and others end up half height or width.


Good call. I've changed it to draw the quad the same size as the SDL surface used after rendering the glyph. Sizes look fine now, but positions are still off.



A related problem?

Quote:
Original post by phantom
I was hoping you hadn't.. but you had... a texture per Glyph is just such a bad bad idea, both speed (texture switching) and resources wise (lots of small textures takes up more space than one larger one).


Yes it had crossed my mind. One step at a time I suppose, once I get the text to render correctly I could modify it have per-string texture capabilities, OR have all the glyphs rendered to a giant sheet and shift around it with texture coords per glyph.

Then again, maybe I won't. The render speed right now is very impressive compared to the first method. Maybe if the game speed starts to become unbearable then I'll give this class a rewrite.



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Right off hand I can't say what's going on now, but I do see another problem that may make you reconsider rendering them all to a single texture. The characters that are supposed to hang below the line are shifted up (and the half-height small characters are the ones that seem to be offset too low, so it might be related). If you rendered them all to a single texture I think SDL_TTF would take care of that for you.

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Have you solved the problem??
I need this sort of code too and don't want to begin a second project like yours...

so if you have the problem cleared please post the solution.


Blackskyliner

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Quote:
Original post by Blackskyliner
Have you solved the problem??
I need this sort of code too and don't want to begin a second project like yours...

so if you have the problem cleared please post the solution.


Blackskyliner


Hi Blackskyliner, my Uni work held me back for a few weeks and the project was on hold, but I'm now working on it again.

I'll post if I find a solution.

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Ok, I'm altering the code to render all glyphs to one texture, and store the UV coords of each glyph into a tidy vector.

So far, the glyphs correctly render neatly to an SDL surface, I've confirmed this by writing the surface to a file using SDL_SaveBMP().

Although probably not done the best way, I think my code to save the texture coords is fine, and so is the drawing code, but the characters won't render.

To verify the drawing positions, I've filled the SDL surface with a colour.

This is what I get:



And here is the code:


bool SYM_FONT::LoadFont(string TTF_Filename, int Size)
{
//Load the font
Font = TTF_OpenFont(TTF_Filename.c_str(), Size);

//Check font loaded
if (Font == NULL)
{
//Return
return false;
}

//Get font attributes
Ascent = TTF_FontAscent(Font);
Descent = TTF_FontDescent(Font);
Height = TTF_FontHeight(Font);
LineSkip = TTF_FontLineSkip(Font);

//TODO: Pre-calculate the size of the glyph sheet
TempGlyphSheet = SDL_CreateRGBSurface(SDL_SWSURFACE, 1024, 512, 32, 0, 0, 0, 0);

SDL_FillRect(TempGlyphSheet, 0, SDL_MapRGB(TempGlyphSheet->format, 255, 0, 255));

//Loop through all chars
for (int i = 0; i <= 254; i++)
{
//Clear the surface
TempGlyphSurface = NULL;

//Render the glyph onto the SDL surface, in white
SDL_Color GlyphColour = {255, 255, 255, 0};
TempGlyphSurface = TTF_RenderGlyph_Blended(Font, i, GlyphColour);

//New temp glyph
TempGlyph = new SYM_GLYPH;

//Get the glyph attributes
TTF_GlyphMetrics(Font, i, &TempGlyph->MinX, &TempGlyph->MaxX, &TempGlyph->MinY, &TempGlyph->MaxY, &TempGlyph->Advance);

//Set the width and height of the glyph
TempGlyph->Width = TempGlyphSurface->w;
TempGlyph->Height = TempGlyphSurface->h;

TempGlyph->MinX = TempGlyph->MinX;
TempGlyph->MaxX = TempGlyph->MaxX;
TempGlyph->MinY = TempGlyph->MinY;
TempGlyph->MaxY = TempGlyph->MaxY;

//Set the glyph rect size
GlyphRect.w = TempGlyphSurface->w;
GlyphRect.h = TempGlyphSurface->h;

//Advance size of current position rect
CurrentPos.w = CurrentPos.x + GlyphRect.w;
CurrentPos.h = CurrentPos.y + GlyphRect.h;

//Blit the glyph onto the glyph sheet
SDL_BlitSurface(TempGlyphSurface, &GlyphRect, TempGlyphSheet, &CurrentPos);

//Set texture coordinates for the glyph
TempGlyph->TexCoords[0].u = (float)CurrentPos.x / 1024;
TempGlyph->TexCoords[0].v = (float)CurrentPos.y / 512;

TempGlyph->TexCoords[1].u = (float)(CurrentPos.x + CurrentPos.w) / 1024;
TempGlyph->TexCoords[1].v = (float)(CurrentPos.y + CurrentPos.h) / 512;

//Advance position of current position rect
CurrentPos.x += GlyphRect.w;

//Put glyphs into rows
if (Count > 40)
{
CurrentPos.x = 0;
CurrentPos.y += Height;
Count = 0;
}

//Push back to glyphs vector
Glyphs.push_back(*TempGlyph);

//Delete temp glyph
delete TempGlyph;

//Free surface
SDL_FreeSurface(TempGlyphSurface);

Count++;
}

//Close the font
TTF_CloseFont(Font);

//Convert the SDL glyph sheet to an OpenGL compliant texture
GlyphSheet = SDL_Surface_To_GL_Tex(TempGlyphSheet);

//Free the temp glyph sheet surface
SDL_FreeSurface(TempGlyphSheet);

return true;
}

void SYM_FONT::RenderText(string Text, float x, float y)
{
int Width, Height, CharID;

//Enable OpenGL texture mapping
glEnable(GL_TEXTURE_2D);

//Bind the glyph sheet texture
glBindTexture(GL_TEXTURE_2D, GlyphSheet);

//Enable blending
glEnable(GL_BLEND);

//Loop through characters
for (int i = 0; i < Text.size(); i++)
{
//Get ID of current char
CharID = (int)Text;

Width = Glyphs[CharID].Width;
Height = Glyphs[CharID].Height;

//Set the colour to white (for correct blending)
glColor3f(1.0f, 1.0f, 1.0f);

//Draw the glyph
glBegin(GL_QUADS);
glTexCoord2f(Glyphs[CharID].TexCoords[0].u, Glyphs[CharID].TexCoords[0].v); glVertex2f(x, y);
glTexCoord2f(Glyphs[CharID].TexCoords[1].u, Glyphs[CharID].TexCoords[0].v); glVertex2f(x + Width, y);
glTexCoord2f(Glyphs[CharID].TexCoords[1].u, Glyphs[CharID].TexCoords[1].v); glVertex2f(x + Width, y + Height);
glTexCoord2f(Glyphs[CharID].TexCoords[0].u, Glyphs[CharID].TexCoords[1].v); glVertex2f(x, y + Height);
glEnd();

x += Glyphs[CharID].Advance;
}

//Disable blending
glDisable(GL_BLEND);

//Disable texture mapping
glDisable(GL_TEXTURE_2D);
}



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    • By DiligentDev
      This article uses material originally posted on Diligent Graphics web site.
      Introduction
      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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    • By TheChubu
      The Khronos™ Group, an open consortium of leading hardware and software companies, announces from the SIGGRAPH 2017 Conference the immediate public availability of the OpenGL® 4.6 specification. OpenGL 4.6 integrates the functionality of numerous ARB and EXT extensions created by Khronos members AMD, Intel, and NVIDIA into core, including the capability to ingest SPIR-V™ shaders.
      SPIR-V is a Khronos-defined standard intermediate language for parallel compute and graphics, which enables content creators to simplify their shader authoring and management pipelines while providing significant source shading language flexibility. OpenGL 4.6 adds support for ingesting SPIR-V shaders to the core specification, guaranteeing that SPIR-V shaders will be widely supported by OpenGL implementations.
      OpenGL 4.6 adds the functionality of these ARB extensions to OpenGL’s core specification:
      GL_ARB_gl_spirv and GL_ARB_spirv_extensions to standardize SPIR-V support for OpenGL GL_ARB_indirect_parameters and GL_ARB_shader_draw_parameters for reducing the CPU overhead associated with rendering batches of geometry GL_ARB_pipeline_statistics_query and GL_ARB_transform_feedback_overflow_querystandardize OpenGL support for features available in Direct3D GL_ARB_texture_filter_anisotropic (based on GL_EXT_texture_filter_anisotropic) brings previously IP encumbered functionality into OpenGL to improve the visual quality of textured scenes GL_ARB_polygon_offset_clamp (based on GL_EXT_polygon_offset_clamp) suppresses a common visual artifact known as a “light leak” associated with rendering shadows GL_ARB_shader_atomic_counter_ops and GL_ARB_shader_group_vote add shader intrinsics supported by all desktop vendors to improve functionality and performance GL_KHR_no_error reduces driver overhead by allowing the application to indicate that it expects error-free operation so errors need not be generated In addition to the above features being added to OpenGL 4.6, the following are being released as extensions:
      GL_KHR_parallel_shader_compile allows applications to launch multiple shader compile threads to improve shader compile throughput WGL_ARB_create_context_no_error and GXL_ARB_create_context_no_error allow no error contexts to be created with WGL or GLX that support the GL_KHR_no_error extension “I’m proud to announce OpenGL 4.6 as the most feature-rich version of OpenGL yet. We've brought together the most popular, widely-supported extensions into a new core specification to give OpenGL developers and end users an improved baseline feature set. This includes resolving previous intellectual property roadblocks to bringing anisotropic texture filtering and polygon offset clamping into the core specification to enable widespread implementation and usage,” said Piers Daniell, chair of the OpenGL Working Group at Khronos. “The OpenGL working group will continue to respond to market needs and work with GPU vendors to ensure OpenGL remains a viable and evolving graphics API for all its customers and users across many vital industries.“
      The OpenGL 4.6 specification can be found at https://khronos.org/registry/OpenGL/index_gl.php. The GLSL to SPIR-V compiler glslang has been updated with GLSL 4.60 support, and can be found at https://github.com/KhronosGroup/glslang.
      Sophisticated graphics applications will also benefit from a set of newly released extensions for both OpenGL and OpenGL ES to enable interoperability with Vulkan and Direct3D. These extensions are named:
      GL_EXT_memory_object GL_EXT_memory_object_fd GL_EXT_memory_object_win32 GL_EXT_semaphore GL_EXT_semaphore_fd GL_EXT_semaphore_win32 GL_EXT_win32_keyed_mutex They can be found at: https://khronos.org/registry/OpenGL/index_gl.php
      Industry Support for OpenGL 4.6
      “With OpenGL 4.6 our customers have an improved set of core features available on our full range of OpenGL 4.x capable GPUs. These features provide improved rendering quality, performance and functionality. As the graphics industry’s most popular API, we fully support OpenGL and will continue to work closely with the Khronos Group on the development of new OpenGL specifications and extensions for our customers. NVIDIA has released beta OpenGL 4.6 drivers today at https://developer.nvidia.com/opengl-driver so developers can use these new features right away,” said Bob Pette, vice president, Professional Graphics at NVIDIA.
      "OpenGL 4.6 will be the first OpenGL release where conformant open source implementations based on the Mesa project will be deliverable in a reasonable timeframe after release. The open sourcing of the OpenGL conformance test suite and ongoing work between Khronos and X.org will also allow for non-vendor led open source implementations to achieve conformance in the near future," said David Airlie, senior principal engineer at Red Hat, and developer on Mesa/X.org projects.

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