I render a scene to my viewport and create a rectangular texture. I want to render the viewport to that rectangular texture which works just fine if i define the texture’s format to be rgba, however, if the format is rgba32f_ so a 32bit floating point texture the rendering speed drops amazingly.
can someone tell me please what i did wrong or how to do it better (with respect to glCopyTexImage)
No. The question was what pixel format does your framebuffer have?
Because if the framebuffer has RGB(A)8 fixed point format, the glCopyTex(Sub)Image call with internal format RGBA32F has to do a format conversion (in the worst case this has to be done on the CPU), while with internal format RGBA8 it can simply copy the data…
I want to implement some algorithm that is described in a paper. Therein geometry is processed by a pair of shaders (that forwards the x,y,z coordinate of a vertex to the fragment shader - the fragment shader writes x,y,z to r,g,b color values - this I figured I need a floating point texture).