How to use texture in 128-bit-color pbuffer?

OpenGL OpenGL: Advanced Coding
1

Hi.
I mat a problom when renderring a rectangle with texture in pbuffer. I just draw a single frame and read it back by glReadPixels. When the pbuffer use 32-bit color, everything wents ok. But when a 128-bit-color pbuffer used, all of the pixels were set to (0, 0, 0, 0). How to use texture in this case? Thanks.

2

Could you provide a bit more information or code? It sounds just too general…

3

Sorry for late. I used a fragment program:
!!ARBfp1.0
PARAM TZERO = { 0.0, 0.0, 0.0, 0.0 };
PARAM TONE = { 0.9, 0.9, 0.9, 0.9000001 };
ATTRIB tcoord0 = fragment.texcoord[0];
ATTRIB tcoord1 = fragment.texcoord[1];

TEMP a, b;
TEMP t;
TEX a, tcoord0, texture[0], 2D;
TEX b, tcoord1, texture[1], 2D;
MOV result.color, b;
END
But result.color was set to be (0, 0, 0, 0) no matter what texture[1] was.

4

There could be a large number of things wrong.

Here are some that I can think of right away:

  • Creating the context for the pbuffer could fail.
  • Making the device/context current could fail (not: it’s not certain that you can use the same context for 32-bit and 128-bit targets)
  • You may have forgotten to share lists into the context.
  • Blending might be turned on – that’s not supported for float targets.

I would suggest you sprinkle your code liberally with “assert(!glGetError())” at the beginning and end of every function in your code, and at opportune intermediary points if functions are long.

5

I had the same problem today. I wanted to render a 32 - bit RGBA texture on GFFX5600. It was the first time I used pbuffers and ARB_render_texture. Took me about a 30 minutes to debug 8 lines of code! Finnaly I discovered that my mesh didn’t fit into the clipping volume. How stupid…

6

Context was created and made current successfully. No Lists. No blending. Mesh in volume. Free window dc failed, but getLastError() returned “Operation succeed”.

7

Do you create the fragment program inside your pbuffer context? Sorry for stupid question…

8

I did create the fragment program for pbuffer. When the pbuffer use 32-bit color, everything wents ok. So I think there may be some problom when pixel format of pbuffer is different from that of window.