   Mipmapping instead of multiple resolution FBOs for bloom?
  Does it make sense to simply run glGenerateMipaps() on the tonemapped image and then Gaussian-blur the first few mip levels, instead of using multiple FBOs with the decreasing resolutions?  While there are more mipmap levels than would be used, the other way incurs the cost of binding different FBOs and with changing resolutions at that.   
  I'd imagine it would depend on...A) Whether the device supports automatic mipmap generationB) How quickly it can generate mipmaps vs. manual downsamplingC) Whether or not you want to use something other than linear filtering when downsamplingandD) Whether or not the extra memory usage is a concernFor B the only way you can know for sure is to profile for different GPU's and drivers.   ;  I'm targeting specific hardware so I assume mipmapping support.Manual generation might be as fast in terms of per-fragment operation cost, but my concern is with the speed of binding multiple framebuffers with changing resolution every frame.  At least a few years ago that was relatively slow.  If one could simply use a large texture and draw the mip levels in the same texture, that would be nice, but it's undefined to read from the texture you're writing to, even if the regions for each operation are disjoint.Linear filtering is sufficient since the different levels are subsequently gaussian-blurred anyway.   