tid_cloud_composite

The post-process pass that resolves the TIDES cloud march and blends it over the scene.

tid_cloud_march writes one jittered sample per pixel into a TIDES-owned target, premultiplied as (scatter, 1 - transmittance). This pass runs a 3x3 tent over that target and blends the result. The tent is what turns the march's per-pixel jitter back into continuous tone: because the jitter comes from interleaved gradient noise, a pixel's neighbours carry well-separated offsets, so a nine-tap average resolves nearly the whole of it.

The filter runs on the premultiplied result, which is the only form a weighted average of a participating medium is linear in.

preseed/tides/sky.module binds the march target into tid_rt each frame and owns the pass's lifetime, disabling it when the part ends.