Problem with MultiTexturing! :(

OpenGL OpenGL: Advanced Coding
1

ok,my app keeps crashing when I try to do this:

glBegin(GL_POLYGON);
//The first triangle
glMultiTexCoord2f(GL_TEXTURE0_ARB,0.0f,1.0f);
glMultiTexCoord2f(GL_TEXTURE1_ARB,0.0f,1.0f);
glVertex3f( -1.0f, 1.0f, 0.0f);// Top

  glMultiTexCoord2f(GL_TEXTURE0_ARB,0.0f,0.0f);
  glMultiTexCoord2f(GL_TEXTURE1_ARB,0.0f,0.0f);
  glVertex3f( -1.0f, -1.0f, 0.0f);// Bottom Left
  
  glMultiTexCoord2f(GL_TEXTURE0_ARB,1.0f,0.0f);
  glMultiTexCoord2f(GL_TEXTURE1_ARB,1.0f,0.0f);
  glVertex3f( 1.0f, -1.0f, 0.0f);// Bottom Right

glEnd();

Any idea why? When I created the multitextures I did this:

glActiveTextureARB(GL_TEXTURE0_ARB);
glBindTexture(GL_TEXTURE_2D, texture[0]);
glEnable(GL_TEXTURE_2D);

glActiveTextureARB(GL_TEXTURE1_ARB);
glBindTexture(GL_TEXTURE_2D, texture[1]);
glEnable(GL_TEXTURE_2D);

Once again,any help would be much appreciated

And,yes,I did glEnable(GL_TEXTURE_2D);

2

Dunno, it should work, but hell, OpenGL is sometimes as quirky as MS software is.

Try this:

Before you make your call to glMultiTextureCoord* insert a call to glActiveTexture setting the correct TMU in action. I do that with my vertex arrays (kinda because I’m not using glMultiTextureCoord), but it might cause the system to respond appropriately.

I think that the way they designed the multitex support on some systems isn’t the standard “expected” way it should be implemented.

Let me know if it works.

Siwko

3

Right, looks quite ok.
Maybe that’s too simple, but have you checked the contents of the function pointers you got with wglGetProcAddres?

4

Oh YES! Got it working! The problem was as you said with the function pointers.I had this call:

glMultiTexCoord2f = (PFNGLMULTITEXCOORD2FARBPROC)wglGetProcAddress(“glMultiTexCoord2f”);

instead of this:

glMultiTexCoord2f = (PFNGLMULTITEXCOORD2FARBPROC)wglGetProcAddress(“glMultiTexCoord2fARB”);

I feel really stupid right now.

Anyway,I finally rendered my image but it appears darker than what I expected.Is that suppose to happen? How can I make it brighter? (Without lights!)
And is there any way to play with the opacity of the other textures? Thanx again guys!

[This message has been edited by TheGecko (edited 08-04-2000).]

5

Maybe got got some odd blendfunction…

Try play around with different blendfunctions and see what happens. glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA) works great for me.

6

Also, you should try gamma correction, using *_gamma_control extensions, or ICM for windows ( Get/SetDeviceGammaRamp )