Discussion
Skimming the rest of BSNES's image-postprocessing OpenGL shaders...
There's a fancy 5-pass upscaling filter accentuating various features.
There's a 2-pass + advanced antialising "xBR" filter which accentuates various edges in YCbCr colourspace.
There's a shader which essentially encodes & immediately decodes PAL video signals.
And by far the most-complex filter is called "CRT Royale"! See next toot...
1/2!
According to a "manifest" file The CRT-Royale filter is a 12-step process consisting of:
1. "Linearize" the input
2. Resample interlaced & misconverged scanlines vertically
3. Resize-blur horizontally for bloom
4. Do so vertically
5. Horizontally blur for halation & refractive diffusion
6. Lanczos-resize the phosphor mask vertically
7. Do so horizontally
8. Resample scanlines horizontally
9. Compute brightness
10. Blur brightness vertically
11. Do so horizontally & merge into dim-pass
...
2/3!
...
12. Apply simulated-curvature & anti-aliasing
I'm not entirely clear what all this means, but the code as vendored into BSNES isn't all that explanatory either. It appears to have been spat out by some sort of build system concatenating files from elsewhere.
What I can say is that it consults some textures representing CRT colour masks.
3/3 Fin for today! Tomorrow: Finish BSNES with "Sourcery"!
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