RE: retrieve OpenGL state from fragment program in CG

There is no way to get at the texture enables in fragment programs.

Additionally, the texture enables have no impact on fragment program execution -- you don't have to enable a texture to use it in your program.  An instruction like

  TEX result.color, fragment.texcoord[0], texture[0], 2D;
 
says you want to use the 2D texture bound to texture image unit 0.  For each texture image unit, the texture of the appropriate type is automatically "enabled".

This is true of straight ARB_fragment_program, all Cg fragment program profiles, and GLSL as well.

If you want to modify your program execution based on a condition, your best bet is to probably use a program parameter/uniform to convey that information to your program.  For ARB_fragment_program, that would be

  glProgramEnvParameter4fvARB(GL_FRAGMENT_PROGRAM_ARB, 0, 
                              (any condition) ? 1.0 : 0.0);

You can then use that value in your shader as needed.

Pat

-----Original Message-----
Sent: Thursday, September 15, 2005 11:12 AM
To: Multiple recipients of list OPENGL-GAMEDEV-L

Hi Guys

I am using CG, and I would want to retrieve opengl state from fragment
program. I just need to know (inside the fragment program) if 2d texture is
enable in one particular texture unit.

/********* main program ************/
glActiveTextureARB(GL_TEXTURE1_ARB);
if (any condition)
  glEnable(GL_TEXTURE_2D);
else

  glDisable(GL_TEXTURE_2D);

/* ----------------------------
fragment program:
well, how to retrieve "texture unit 1" status without
using parameters.
is it possible to retrieve this kind on information from glstate.*?
how?
... */


Thx guys!
RIX

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