Hello, I have an OpenGL app where I'm writing video frames to textures. The video frames are semantically opaque but the alpha in the source pixels is set to 0xff, so I have been using glTexImage2D with format=GL_RGBA and internalFormat=GL_RGB to indicate that the input has a valid alpha channel but that the OpenGL implementation could discard it if it wanted to (e.g., if the hardware had native support for GL_RGB which was faster than its GL_RGBA support, or something).
This has worked well for me on most systems, but today I found that it results in poor glTexSubImage2D() performance on an Intel IGDNG_M GPU (i965-based) with MESA 7.7.1 (using Ubuntu Lucid). Because internalFormat is GL_RGB instead of GL_RGBA, _mesa_texstore_argb8888 takes a slow path by using _mesa_swizzle_ubyte_image instead of memcpy_texture. Wouldn't it make sense for _mesa_texstore_argb8888 to use memcpy_texture in this case? Or maybe it is right to not do that since there is no way for it to know that the alpha component in the input is already set to 0xff ... but in that case shouldn't it at least take the third path--the one that uses PACK_COLOR_8888(0xff, ...) ? _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
