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joelr

Mipmap white dots problem

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joelr    122
Hi there, I have a bug in a texture loading class, very annoying one. I get white dots scatered around the border of an object when I use mipmapping (gluBuild2DMipmaps), with any 4 mipmap min filters. But I won''t get any artifact if I use glTexImage2D for level 0 only. I even noticed white dots inside objects, following the borders of triangles. There ain''t any holes or seams in the model, I double checked that. I believe the white I see comes from some white that is not UV mapped on my texture, but every object has a good color border around it''s UVs, and anyway mipmap level 0 won''t show me this. Any clue? joel

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acw83    174
Try using the software mode of OpenGL, it should in theory always work as a reference. If it looks ok, then the problem is probably in your hardware driver.

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mhays    122
Are you clamping your UV coordinates? Perhaps if they are repeating and you have some sort of precision error, this problem could occur.

M

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joelr    122
The inside dots were caused by an approx error (the white was bleeding inside because one polygon out of two were really stretched and the transition between color and white did not happen at the same level in those). I had to change my UVs some.

I still can''t find why there are some white dots on the outer edge though. That ain''t the UV clamping, or the driver (thanks anyways). I guess it''s still the UVs that should be organized another way, so the lesson is to never forget to check how some UV maps perform bad on mipmapped textures (what I mean is that to map a truncated cone, you should not unwrap it, as it distorts the polygons more, but rather plane map it from above).

Thank you guys.

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