Thank you! The best in my case would be fastest, I am not using mipmaps but I would like to know how to do that. Besides scaling I have another issue to address which is reading downsamples pixels back, Currently I am using glReadPixels which is slow, I have also tried asynchronous fetching but the results are the same. Usually it takes 3 to 5ms which is ok but at some instance, like after every 10 or 12 frames, it peaks to 15ms which is not ok.
Nisar On Thu, Nov 3, 2011 at 10:39 PM, Christopher Wright < [email protected]> wrote: > The nature of my Plugin is such that I need to scale input image to a > different size before drawing. What is the best way of scaling textures > using OpenGL? I am currently using FBO but I need to know what is the best > and fastest way of doing this in OpenGL. > > > For what value of "best"? Fastest? Least memory consumed? Highest > filtering quality? > > FBO is probably the way to go, but that doesn't actually mean much - do > you use mipmaps to aide in downsampling? Are you doing a multi-pass > downsample, or a single pass? Are you doing simple bilinear or trilinear > filtering, or something expensive like lanczos resampling? Are the images > large enough to require tiling, or can you always just use a single raster > operation to draw them? > > You should measure the time taken among various methods (FBOs, shared > contexts, etc), and their "bestness", and chose the one that best fits your > goals. > > -- > Christopher Wright > [email protected] > >
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