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/* * Implement SVGF style denoising as bgfx example. Goal is to explore various * options and parameters, not produce an optimized, efficient denoiser. * * Starts with deferred rendering scene with very basic lighting. Lighting is * masked out with a noise pattern to provide something to denoise. There are * two options for the noise pattern. One is a fixed 2x2 dither pattern to * stand-in for lighting at quarter resolution. The other is the common * shadertoy random pattern as a stand-in for some fancier lighting without * enough samples per pixel, like ray tracing. * * First a temporal denoising filter is applied. The temporal filter is only * using normals to reject previous samples. The SVGF paper also describes using * depth comparison to reject samples but that is not implemented here. * * Followed by some number of spatial filters. These are implemented like in the * SVGF paper. As an alternative to the 5x5 Edge-Avoiding A-Trous filter, can * select a 3x3 filter instead. The 3x3 filter takes fewer samples and covers a * smaller area, but takes less time to compute. From a loosely eyeballed * comparison, N 5x5 passes looks similar to N+1 3x3 passes. The wider spatial * filters take a fair chunk of time to compute. I wonder if it would be a good * idea to interleave the input texture before computing, after the first pass * which skips zero pixels. * * I have not implemetened the variance guided part. * * There's also an optional TXAA pass to be applied after. I am not happy with * its implementation yet, so it defaults to off here. */ /* * References: * Spatiotemporal Variance-Guided Filtering: Real-Time Reconstruction for * Path-Traced Global Illumination. by Christoph Schied and more. * - SVGF denoising algorithm * * Streaming G-Buffer Compression for Multi-Sample Anti-Aliasing. * by E. Kerzner and M. Salvi. * - details about history comparison for temporal denoising filter * * Edge-Avoiding À-Trous Wavelet Transform for Fast Global Illumination * Filtering. by Holger Dammertz and more. * - details about a-trous algorithm for spatial denoising filter */