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Crawl

My textures won't clamp.......

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I'm drawing a simple skybox with GL_CLAMP so the edge's won't show up, it works fine on the 2 NVidia cards i've tried it on but it fails to clamp the textures on my ATI Radeon 7200...... (under Win98se) Anyone know why ?? (without stating the obvious) And is there a solution to this..... -Crawl [edited by - Crawl on June 7, 2002 3:31:51 PM]

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ATI''s implementation of GL_CLAMP works differently from NVIDIA''s, such that the seams in skyboxes show up. Is that what you''re seeing? Try using GL_CLAMP_TO_EDGE. It should fix your problem.


Dave "Myopic Rhino" Astle
Executive Producer and COO, GameDev.net
Game Programmer, Avalanche Software
Author, OpenGL Game Programming

"Leaking and bleeding... that''s what happens when you don''t relax"

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quote:

ATI''s implementation of GL_CLAMP works differently from NVIDIA''s, such that the seams in skyboxes show up. Is that what you''re seeing? Try using GL_CLAMP_TO_EDGE. It should fix your problem.



I also noticed that. Infact, Nvidia''s GL_CLAMP seems to be an implicit GL_CLAMP_TO_EDGE. The border colour is totally ignored. Is that behaviour documented somewhere ? AFAIK, it is inconsistent with the OpenGL standard.

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It''s a known issue. I can''t remember if its a hardware issue where everything before the Geforce 3 couldn''t do the expected GL_CLAMP and instead forced GL_CLAMP_TO_EDGE or if they kept it that way so to not break the many apps out there already using GL_CLAMP.

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