Commits on Sep 6, 2018

1. Add a new benchmark, `large-blur-image`. …

   This benchmark tests the performance of large blur radii combined with large
   images.

   

   pcwalton committed Sep 6, 2018
   b9ae5a3

2. Allow the output path to be specified for the `wrench png` subtool

   

   pcwalton committed Sep 6, 2018
   28f977c

3. Fix a reftest that relied on blurring out-of-bounds image data

   

   pcwalton committed Sep 6, 2018
   e509c87

4. Rewrite the blur shader to remove the variable-length loop and to use… …

   … the
   
   texture filtering hardware more effectively.
   
   This new shader performs Gaussian *resampling* instead of regular convolution.
   It samples in between texels to reduce the number of taps.
   
   The speed is about the same as the existing technique. It is nevertheless the
   fastest blur method that I could come up with. In particular, it exceeds the
   performance of the Kawase and dual Kawase blur techniques. The speed comes from
   working at lower resolution and incurring fewer downsampling and upsampling
   passes. As is often the case, ALU performance does not really seem to be the
   limiting factor; it's mostly memory bandwidth, which is why downsampling is so
   important. Further improvements should come from not doing the downsampling at
   all and instead rendering the blurred content at low resolution to begin with.
   
   Closes #2821.

   

   pcwalton committed Sep 6, 2018

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