OpenGL questions about disable rendering

OpenGL questions about disable rendering

Post by Jianlong Zho » Thu, 05 Jun 2003 23:20:11



Hi, all,

I want to know whether it is possible in OpenGL to disable rendering
when reading and writing something in the framebuffer?
I want to write and read(!) something in the framebuffer but meanwhile
the framebuffer shouldn't be drawn.

There are two functions related to this:
glDrawBuffer - specifies a buffer to render to
glReadBuffer - specifies the buffer where pixels are read from

But I couldn't find the function for disabling rendering the framebuffer
to the monitor! Or isn't it possible to disable it and the current read
buffer is displayed?

Best regards,

Jianlong

 
 
 

OpenGL questions about disable rendering

Post by Jianlong Zho » Wed, 18 Jun 2003 18:06:47


Hi,

I am using OpenGL and the register combiners approach for programming
volume rendering. My graphics card is Geforce 4. I hope someone who use
this kind of board and OpenGL can answer my questions.

I have a question about register combiners and pixel transfers /
dependent textures. I calculate a specific value using register
combiners and store it in texture2. Now I do not want to use this value
directly but use it as an index for pixel transfer. Is it possible to
specify a pixel transfer mapping during register combiner operations? I
think about the following scenario: The register combiners calculate
value X and while storing it in texture2 the pixel mapping
takes place and the mapped values (using glPixelMapfv
(GL_PIXEL_MAP_I_TO_G,...) ) are stored. Is this possible?
If not - can I combine register combiners and dependent texures? So I
compute X and store it in texture2 - and use texture 3 afterwards in a
way that texture2 is the index for texture3... Is this realistic or is
it impossible? I hope I could describe my problem! Thanks for the answers,

Best regards,

Jianlong