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Roland

Environment Mapping on Radeon 9700 (Performance)

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Hello, I''m using environment mapping in my game. It works well on a Geforce, but on a Radeon 9700 the performance is very bad (From 130 fps without ENVMapping to 10 fps with). The environment map is on texture unit 2 and the texture of the object is on texture unit 1. When I only use environment mapping on texture unit 1 without a normal texture the performance is ok. Any ideas why? What must I do to solve these problems? Thanks in advance, Roland

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What happens when your envmap is on unit 2 and you turn of tex gen? I''m just wondering whether this is a texture problem or a coord generation problem.

Anyways, it sounds like this could be a driver bug. Send a sample to devrel@ati.com any some one can take a look at it.

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When I remember it right, it was not faster, when I disabled texgen. But I'll try it on friday, when I can use the Radeon again.
A driver problem? Could be possible. I'll ask ati.

Does anyone know, if all texture units of the radeon have the same capabilities / are all able to do environment mapping? Or is perhaps only the first able to do so?

[edited by - Roland on June 18, 2003 3:48:49 PM]

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On the 9700 (and 8000+) all texture units should be fully capable. On the Radeon 7000+, there are some restrictions as to what type of textures you can put on what unit (like Enviromental Bump Mapping, 3D textures, and cubemaps), but nothing strictly to do with enviroment mapping.

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Could the problem perhaps be related to the combiner. I''m using COMBINE_EXT with INTERPOLATE_EXT.
That shouldn''t be a problem for a radeon 9700 pro, or?

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Ok I tried it without texture coordinate generation and there was next to no performance difference without it.

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This would indicate that it''s not a problem with enviroment mapping, but rather a problem with the texture (or shader) used for the enviroment map.

How big is the texture? How are you generating the image? Are you using render to texture or copyTexImage? Are you loading it with glTexImage2D each frame?



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The texture is static and loaded only once unsing glTexImage2D, when the program is started. It consists of 6 512x512 Pixel PNGs.

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im not a 3d geek, but as i know u dont need envtextures with such a high resolution. 6*256 is enough but 6*128 should also suit well.

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OK, On monday I'll try it with low res textures. But 512x512 shouldn't be a serious problem for a Radeon 9700, or?

[edited by - Roland on June 21, 2003 7:32:48 AM]

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