Use min importance in volumes
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Authored by Alaska (Alaska) on Nov 22 2022, 9:23 AM.

Details

Reviewers

Brecht Van Lommel (brecht)
Weizhen Huang (weizhen)

Summary

Use both the max and min importance for deciding which branch
of the light tree to traverse down when in volumetric materials.

Here are some comparisons:

	Current soc-2022-many-lights-sampling	This patch	Not using the light tree
4 samples per pixel
1024 samples per pixel

Repository

rB Blender

Branch

min_importance_volumes (branched from master)

Build Status

Buildable 24805
Build 24805: arc lint + arc unit

Alaska (Alaska) created this revision.

Here's the .blend file used for testing

Volume test.blend867 KBDownload

intern/cycles/kernel/light/tree.h
145	When `in_volume_segment`, we use the shortest distance from a point to the ray, so using `max_distance` does not make sense; instead, we want to add \theta_a and \theta_b in the future (see Eq 4. in the original paper). But when `in_volume`, we have a shading point and could compute the importance the same way as we are not in a volume, except that `cos_incidence_angle = 1.0f`. So please keep this block with `if (in_volume_segment) {` for now, otherwise it looks fine.