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Loops slow everything down.

Started by ShlomiSteinberg Jan 25, 2003 at 1:19 PM 5 replies 150+ views
Original Post
ShlomiSteinberg
ShlomiSteinberg
In my OpenGL programm I have a loop, which is executed every frame: for (int i=0;i<5000;i++) { glBlendFunc(GL_DST_COLOR,GL_ZERO); // Bind Texture DrawQuad(); glBlendFunc(GL_ONE,GL_ONE); // Bind texture DrawQuad(); } Now I lose about 8-10 fps because the CONTENTS of the loop. I''m using a Pentium 3 700Mhz and a GeForce 4. If I use this however: glBlendFunc(GL_DST_COLOR,GL_ZERO); // Bind Texture for (int i=0;i<5000;i++) DrawQuad(); glBlendFunc(GL_ONE,GL_ONE); // Bind texture for (int i=0;i<5000;i++) DrawQuad(); some of the quads are blended together. What can I do to speed this but not blend the quads?
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Lunatic Raven
Lunatic Raven
One thing I can think of is, are there glBegin() and glEnd() within your DrawQuad() function, because if there is, you should gain a speed increase by getting them outside of the loops.
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Julio
Julio
you might try display lists if your geometry is static. that should speed it up a bit.

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ShlomiSteinberg
ShlomiSteinberg
quote:
Original post by Lunatic Raven
One thing I can think of is, are there glBegin() and glEnd() within your DrawQuad() function, because if there is, you should gain a speed increase by getting them outside of the loops.



I have to rotate and translate each quad differently and I need to change the blend function and bind a texture...
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ShlomiSteinberg
ShlomiSteinberg
quote:
Original post by Julio
you might try display lists if your geometry is static. that should speed it up a bit.



Thats right! I have forgotten display lists.. I don''t think I can use glRotate/glTranslate inside a display list, can I?
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ShlomiSteinberg
ShlomiSteinberg
I have tried to use display lists, but I have lost about 6 fps!! What is wrong? I compile the display lists with the glBegin()/glEnd() and everything I do is rotate the lists.
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Tron3k
Tron3k
I don''t think display lists give much advantage for rendering only a single quad at a time.

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