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OpenGL OpenGL + SDL 2D optimization help

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Hello gentlemen, I'm a newb when it comes to OpenGL. Recently, I've ported my 2D game engine from Win32 API to OpenGL (for rendering) and SDL (window handling). However, my frame rate dropped significantly from 200 FPS to about 35 FPS. Since it's just a port of the graphics API, it most def is the rendering that is causing this slowdown. My engine renders a scene with about 200 tiles (each tile = 16x16) which is handled by my TileManager class. The tile images are pulled from a few tilesheets. When I render, TileManager goes through each tile in the scene and it renders each Tile using this code:
glBindTexture( GL_TEXTURE_2D, m_texID );

GLfloat portionXstart, portionYstart;
GLfloat portionXend, portionYend;

// This part finds the area of the tile image in the tilesheet
portionXstart = (GLfloat)imgOffsetX / m_imageWidth;
portionYstart = (GLfloat)imgOffsetY / m_imageHeight;
portionXend = (GLfloat)(imgOffsetX+cropWidth) / m_imageWidth;
portionYend = (GLfloat)(imgOffsetY+cropHeight) / m_imageHeight;

glBegin(GL_QUADS);

	glTexCoord2f(portionXstart, portionYstart); 
	glVertex2i(posX, posY);

	glTexCoord2f( portionXend, portionYstart);
	glVertex2i(posX + cropWidth, posY);

	glTexCoord2f(portionXend, portionYend); 
	glVertex2i(posX + cropWidth, posY+ cropHeight);

	glTexCoord2f(portionXstart, portionYend); 
	glVertex2i(posX, posY + cropHeight);

glEnd();


Not sure if it helps, but I set up the window using this code:
SDL_SetVideoMode(width, height, 32, SDL_OPENGL | SDL_HWSURFACE );
glViewport(0, 0, width, height);
glEnable(GL_TEXTURE_2D);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0.0, width, height, 0.0, 0.0, 100.0);
glMatrixMode(GL_MODELVIEW);
glClearDepth(0.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);


I've tried commenting out the glBindTexture and just sticking to one texture, but to no avail. :( I've been reading up on vertex buffers objects/vertex arrays, will those help my cause? Any help would be greatly appreciated. Thanks! :)

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I tried doing glBegin/glEnd once, but it doesn't seem be binding the texture correctly. I see a weird hodgepodge of tiles only from only 1 tilesheet.

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Right, sorry, you can't call glBindTexture inside a glBegin/glEnd pair.

You should definitely look into VBOs. Also, if your tiles use different textures, you should sort them by texture to minimize texture changes.

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Are you not drawing objects that are not seen? (ie, culling)

There are better options than using inmediate mode (glbegin/glend)
For instance VBOs, display lists (less obsolete than inmediate mode)

Put
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0.0, width, height, 0.0, 0.0, 100.0);
in your resize code


In you render code put:
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
// draaw whatever...

Remove those lines from your init code, it does not make sense.

Are you using always the same texture atlas? In this case,
glBindTexture( GL_TEXTURE_2D, m_texID );
should be done only once.

This is my SDL init code

SDL_GL_SetAttribute(SDL_GL_RED_SIZE, 8);
SDL_GL_SetAttribute(SDL_GL_GREEN_SIZE, 8);
SDL_GL_SetAttribute(SDL_GL_BLUE_SIZE, 8);
SDL_GL_SetAttribute(SDL_GL_ALPHA_SIZE, 8);
SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 0);
#ifndef TARGET_WINDOWS_XP
SDL_GL_SetAttribute(SDL_GL_RETAINED_BACKING, 0);
SDL_GL_SetAttribute(SDL_GL_ACCELERATED_VISUAL, 1);
#endif

#ifdef TARGET_WINDOWS_XP
m_surface=SDL_SetVideoMode(480, 320, 0, SDL_OPENGL);
if (m_surface==NULL) {
g_log->WriteInfo("SDL could not set the video mode. Error: %s.\n", SDL_GetError());
return false;
}
SDL_WM_SetCaption("Level Loader", NULL);

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vertex arrays wont help at all.
Im not sure what the problem is, 35fps (on what hardware/resolution)
does seem very low for 200 quads (unless they are all fullscreen quads) esp if youre not changing textures etc

though 35fps doesnt sound slow enuf for software opengl (then again u may have a fast cpu)

If u put up an .exe I might have a look at how it performs on my machine

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It sounds as though perhaps you use OpenGL to draw to an SDL system memory surface or something like that, which will cause the image to be copied to system memory unnecessarily. Try creating a minimal application using your set-up code, which draws a single triangle, and see if it still happens. If so, post the code for that application.

200 tiles is nothing, you should easily be able to draw thousands without that slowdown, even when changing textures and using immediate mode. Some other questions that can be relevant:
What OS/hardware/drivers/programming environment are you using?
Do you compile in debug mode?
Do other OpenGL applications work fine?

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Wow, I am a total newb. My friend suggested that I try upgrade my drivers (NVIDIA). So I did. When I ran the app, it rendered at 60fps. After turning VSYNC off, I got 500FPS...

Pwned. :(

I'm a bit frustrated that I've been spending a few days trying to fix this thing. I guess it's my punishment for not expecting it was a driver issue. Anyhow, I greatly appreciated all the help! Thanks guys in aiding me in this fruitless endeavor! :)

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