How to multitexture?

Graphics and GPU Programming Programming

Started by ic0de December 02, 2011 12:53 AM

2 comments, last by ic0de 12 years, 4 months ago

1,014

Author

December 02, 2011 12:53 AM

So i'm trying to layer two textures on top of each other, when I render with one texture here is what I do.

I bind my texture.glBindTexture(GL_TEXTURE_2D, tex[0]);

And I draw my vertex arrays



glEnableClientState(GL_VERTEX_ARRAY);

glEnableClientState(GL_NORMAL_ARRAY);

glEnableClientState(GL_TEXTURE_COORD_ARRAY);





glVertexPointer(3, GL_FLOAT, 0, vertices);

glNormalPointer(GL_FLOAT, 0, normals);

glTexCoordPointer(2, GL_FLOAT, 0, texcoords); 



glDrawArrays(GL_TRIANGLES, 0, numtriangles*3);



glDisableClientState(GL_VERTEX_ARRAY);

glDisableClientState(GL_NORMAL_ARRAY);

glDisableClientState(GL_TEXTURE_COORD_ARRAY);

This works great with one texture.

When I want to do it using two, I think this is what I'm supposed to do:

Bind my textures



glActiveTexture(GL_TEXTURE0);

glBindTexture(GL_TEXTURE_2D, tex[0]);

glEnable(GL_TEXTURE_2D);



glActiveTexture(GL_TEXTURE1);

glBindTexture(GL_TEXTURE_2D, tex[1]);

glEnable(GL_TEXTURE_2D);

[color=#1C2837][size=2]

And I draw my vertex arrays



glEnableClientState(GL_VERTEX_ARRAY);

glEnableClientState(GL_NORMAL_ARRAY);



glClientActiveTexture(GL_TEXTURE0);  

glTexCoordPointer(2, GL_FLOAT, 0, texcoords);  

glEnableClientState(GL_TEXTURE_COORD_ARRAY); 





glClientActiveTexture(GL_TEXTURE1);  

glTexCoordPointer(2, GL_FLOAT, 0, texcoords);  

glEnableClientState(GL_TEXTURE_COORD_ARRAY); 



glVertexPointer(3, GL_FLOAT, 0, vertices);

glNormalPointer(GL_FLOAT, 0, normals);



glDrawArrays(GL_TRIANGLES, 0, numtriangles*3);



glDisableClientState(GL_VERTEX_ARRAY);

glDisableClientState(GL_NORMAL_ARRAY);

glDisableClientState(GL_TEXTURE_COORD_ARRAY);

As far as I know it should work but when I try I only see one texture.

What is wrong?

Firestryke31

350

December 02, 2011 04:22 AM

I'm not 100% on this, but perhaps it has something to do with a lack of this? Just based on what I read on the glTexCoordPointer ref page:

For OpenGL versions 1.3 and greater, or when the ARB_multitexture
extension is supported, glTexCoordPointer updates the
texture coordinate array state of the active client texture unit,
specified with glClientActiveTexture.[/quote]

Having never done multitexturing before I'm just going by what looks right, so you might need to do a little research to confirm it.

Edit: Just reread your post. /facepalm I need to slow down and not post when sick and tired.

21st Century Moose

13,459

December 02, 2011 10:51 AM

You also need to set your glTexEnvs for each texture unit according to how you want the textures to be blended together. So it's a glActiveTexture call for the relevant unit, followed by a bunch of glTexEnv calls.

Incidentally, you have a bug in your second code listing: glDisableClientState (GL_TEXTURE_COORD_ARRAY) will only affect the current client active texture, so you'releaving the TexCoordArray enabled for GL_TEXTURE0.

Direct3D has need of instancing, but we do not. We have plenty of glVertexAttrib calls.

ic0de

1,014

Author

December 02, 2011 01:36 PM

You also need to set your glTexEnvs for each texture unit according to how you want the textures to be blended together. So it's a glActiveTexture call for the relevant unit, followed by a bunch of glTexEnv calls.

Incidentally, you have a bug in your second code listing: glDisableClientState (GL_TEXTURE_COORD_ARRAY) will only affect the current client active texture, so you'releaving the TexCoordArray enabled for GL_TEXTURE0.

thanks it works now

How to multitexture?

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