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Texture mapping discolorings

Started by Toolmaker Dec 1, 2008 at 7:58 AM 3 replies 750+ views

Original Post

Dec 1, 2008 at 7:58 AM

I'm currently working on some OpenGL code for the application I professionally work on. I'm not well versed with OpenGL. What I did was update the way our application renders bitmaps. My predecessor never knew about textures on the videocard, so he figured it was a cool idea to just render all bitmap pixels as colored quads. I patched up his code by dumping the bitmap as a texture_2d on the GPU, and then rendering a textured quad with the texture bound to it. It all works great, with 1 exception. It somehow blends in additional color from the quad I draw. I turn off GL_BLEND with glDisable() before calling glBegin() and no errors occur. This is the output:

And the original can be seen here:

Any ideas? Toolmaker

Gage64

Dec 1, 2008 at 8:02 AM

I think this should work:

glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);

I'm also not very familiar with OpenGL so I refer you here for more info.

Actually there should be a newer version of that particular chapter freely available somewhere, you might try looking for it.

Toolmaker

Dec 1, 2008 at 8:09 AM

Sorry to tell, but that doesn't work.

Toolmaker

Gage64

Dec 1, 2008 at 8:19 AM

What if you change GL_DECAL to GL_REPLACE?

Toolmaker

Dec 1, 2008 at 8:27 AM

Same result... But I'm reading through some code and I ran into this:

        GLfloat matdif[4] = { 1.0f, 1.0f, 1.0f, 1.0f}; // render color                glMaterialfv (GL_FRONT_AND_BACK, GL_DIFFUSE, matdif);

Could that be related?

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