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texture problem

Started by hello_there Nov 27, 2003 at 1:49 AM 7 replies 400+ views

Original Post

Nov 27, 2003 at 1:49 AM

I''m using tga files for my textures. When i map it to a triangle is repeats a bit of the top on the bottom and it looks real bad. Anyone know what might cause it to do this. I don''t think it''s the texture coordinates.

Myopic Rhino

452

Myopic Rhino

Nov 27, 2003 at 1:55 AM

Sounds like the values you''re passing for format and/or type don''t match what''s actually in the TGA.

hello_there

Author

hello_there

Nov 27, 2003 at 2:35 AM

I''m using format GL_RGBA and type GL_UNSIGNED_BYTE. I''m also using gluBuild2DMipmaps(). When i try to use glTexImage2D() now the texture just appears as white.

Fingers_

Nov 27, 2003 at 2:35 AM

If your texture coordinates are from 0 to 1 and you''re using bilinear filtering, the bottom pixels of the texture will be visible at the top and vice versa (blended halfway). This will be more visible if it''s using a smaller mipmap so adjusting the texture coordinates won''t always help. Have you tried using CLAMP_TO_EDGE?

hello_there

Author

hello_there

Nov 27, 2003 at 2:59 AM

Nope. How do you do that? Also how would i make it trilinear filtering?

Fingers_

Nov 27, 2003 at 3:15 AM

trilinear would be GL_LINEAR_MIPMAP_LINEAR .. But any filtering besides GL_NEAREST (which you don''t want) will have the same problem. It''s just how texture coordinates work.

Edge clamping requires OpenGL 1.2 or later and you use it by putting GL_CLAMP_TO_EDGE (0x812f) in the texture parameters instead of GL_REPEAT or GL_CLAMP.

hello_there

Author

hello_there

Nov 27, 2003 at 5:48 PM

Thanks that worked but i had to use 0x812f because GL_CLAMP_TO_EDGE didn''t work.

fireking

Nov 27, 2003 at 7:15 PM

its not part of the original 1.1 spec, so it must be defined

_the_phantom_

496

_the_phantom_

Nov 27, 2003 at 9:58 PM

for stuff beyond 1.1 i recomend getting a hold of benjamin bunny''s GLee lib as it makes using ''em painless and fun :D

also, there is an artical on Gamedev about going beyond 1.1''s features, its probably a good idea for you to take a shifty at that as well

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