Sixth patch to 1.5.

New Features:

• Path-traced ambient lighting for clouds. It is not recommended to use this for real-time applications, since it is expensive and noisy, but it’s very useful for providing a reference for tweaking the usual height-based ambient lighting parameters.
• Height-based self-shadowing approximation for clouds, similar to Cyberpunk 2077’s implementation, that you can use in lieu of real self-shadowing to improve performance.
• Reprojection/denoising can now use catmull-rom filtering to reduce blurriness when the camera moves.
• New light sampling strategy parameter for cloud layers that allows you to select between “all”, “stochastic”, and “brightest” sampling modes. Stochastic/brightest sampling can improve performance dramatically when you have multiple celestial bodies.
• Neighborhood clamping for temporal denoising/reprojection is now optional, with an adjustable threshold to reduce the intensity of the effect. Disabling it may increase blurriness, but results in much better noise reduction.

Fixes:

• Remove high-detail self-shadow option to improve performance (branching on uniform variable in inner loop was slowing things down).
• Compile performance-altering branches into shader variants, improving performance for those code paths. For instance, disabling self-shadowing now provides an appreciable boost.
• Only updated pixels are denoised, dramatically improving the performance and quality of denoising when reprojection is in use.
• Fix issue where clouds were too dark when composited on top of geometry.
• Fix banding on geometry when cloud layers are low to the ground.
• Add option to always render clouds behind geometry (marginally improves compositing performance).
• Fix unnoticeable but technically incorrect cloud self-shadowing bug.
• Multiple fixes to cloud compositing over geometry.