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View Full Version : ARB_texture_compression and SGIS_generate_mipmaps



JanHH
07-26-2003, 08:24 PM
Can I use the above mentioned extensions togehter? It looks like I can but I don't trust it. And is it true that for using texture compression, the ONLY thing I have to do is to change the third parameter of the glTexImage2D-Command to something with "COMPRESS", for example, GL_COMPRESS_RGBA_ARB?

Jan

JanHH
07-26-2003, 09:04 PM
And another point, am i assuming right that it is not wise to use texture compression for textures that are changed later with glCopyTexSubImage... because the new image first has to be compressed, eating performance?

elias
07-27-2003, 08:16 AM
I don't know if you can use the two extensions together, but I can answer your other questions:

1. Yes, it's enough to use the GL_COMPRESSED_* pixel formats to enable compression.
2. According to the spec, only the lower left corner of a compressed texture can be altered, and even then the rest of the texture is undefined. If you need compressed texture updating, you need to use specific compression formats like GL_EXT_texture_compression_s3tc.

- elias