You are most likely turning on software rendering by accessing the texture in the vertex shader.
Textures are uploaded as 8 bit per component which is the standard for images and video. Changing this to 32 bit floats is extremely inefficient. There might be a way to specify the GPU storage to be 32 bit float, but typically the driver would do the conversion slowly and not the GPU. Render to texture using gemframebuffer with a 'format FLOAT' message will give a float texture to read from in the shaders. I see that you filed a bug that this object does not work on your machine though. Maybe you can try another? You could try changing the code in pix_texture and recompiling. Change the format from GL_UNSIGNED_BYTE to GL_FLOAT to see if that works and speeds it up. The uploaded texture will not contain the right values since the GPU expects a float and the image is still 8 bit. I probably won't have time to work on this for a few weeks, but I want to get the framebuffer working better. On 9/9/07, cyrille henry <[EMAIL PROTECTED]> wrote: > > hello, > > i'm tring to do more physics on the GPU, and i'm facing some problems. > simulation results can be compute on texture (just like the wave example i > send month ago), so now i'd like to use this texture to move vertex. > > if i acces to a texture with a vertex shader just like on a fragment > shader, then it's very slow. > (cpu is at 100%) > > i found that : > "vertex textures must be 32-bit-per-component textures, floating point, > and they can't use any filtering mode except nearest filtering." > > i tryed "quality 0" to pix_texture in order to have the nearest filtering > mode, but i'm not sure about the 32 bit per component texture. > is it the default on Gem? > if no, is it possible to change it? > > anyone already have an exemple how to use a texture to displace vertex? > > > thanks > > cyrille > > _______________________________________________ > GEM-dev mailing list > [EMAIL PROTECTED] > http://lists.puredata.info/listinfo/gem-dev >
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