Nehe Lesson 19
May 10, 2006 07:53 PM
Can someone please explain to me why, when I ammend Nehe's Lesson 19 and enable GL_DEPTH_TEST, all of a sudden the black borders from the particle.bmp start to appear. They are still semi transparent.
I'm getting the feeling that the blending function is processing the particles nearest to farthest, rather than the other way around. Which is what is causing the problem.
I should also point out that I increased the width of the particles from 1 to 10 in order to make the problem more apparent.
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100
May 10, 2006 08:18 PM
enabling depth testing causes fragments that would normally pass through to be discarded due to the fragments of the particles quad being closer to the camera than they are. if part of the object being drawn after the quad where obscured by the particles quad, it would indeed outline that area.
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May 11, 2006 03:43 AM
So how do I make my particle emitter appear behind other geometry or particle emitters?
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1,164
May 11, 2006 03:59 AM
You should disable writing to the Z-buffer while drawing transparent things, but still test for depth. And draw all transparent things last. This isn't perfect, but it's pretty close.
132
May 11, 2006 04:11 AM
To disable writing to Z buffer use:
glDepthMask(FALSE);
glDepthMask(FALSE);
May 11, 2006 05:49 AM
Many thanks for that, and thanks for the layman's code at the bottom. :)
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