OpenGL pixel manipulation (offset color map issue)

Hi everyone.
I have a strange trouble with OpenGL.
The scenery:
-nVidia GTX560 Ti from ASUS.
-Using nVidia drivers version 290.10.
-CPU core i5 3.2Ghz (model 650) on ASUS MB
I’m trying build an address map based on colors.
What I am doing:
+Off-screen rendering
+Load textures and associate pure white color silhouette texture for address mapping (non 100% opaque pixel=white (0xFFFFFFFF) and opacity set to 100%, either pixel=back (0x0) an full transparency)
+Using ARB buffers for pixel read/write
+Clear ALL buffers (stencil, color, depth, etc… even though only color buffer is relevant)
+Render user scene view (i.e normal render, with lights, fog, etc…)
+Render for composing a color address key:
+Select an auxiliary (GL_AUX*) buffer
+Take the first 24bits offset from a structure related with rendered texture
+Use these bits as RGB color components
+Set Alpha component always as 0xFF
+Set as active texture the white silhouette associated with the rendered texture
+Set as active color my composed color
+and so far until all structure address is stored into OpenGL auxiliary color buffers.
The problem:
Some times the colors are not correct and fails when I rebuild the addresses from GL_AUX’s, giving me a seg. fault.

I already tried:

and use GL_BACK instead GL_AUX*

Any ideas?

Thanks for read.

I’m trying build an address map based on colors.

What does that mean? What is an “address map”? You need to tell is more about what you’re trying to do.

Hello Alfonse.
“address map” means take an offset, lets say 64 bits, and split into 8 bits packets. This packets are the color components for glColor(…). With Alpha=255, there are 3 colors (RGB+RGB+last 2 components)

Each time that I render a blank-transparent&white-opaque silhouette, the components of memory offset are drawn.

But I need the colors without “errors”, plain color, bit per bit, in order to rebuild the original offset.

That’s the problem: sometimes OpenGL does not accurate color representation and rebuilded address is wrong.

I expect be a little more clear.

Thanks for reply.

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