Threejs Shadow Systems

Shadow Systems

Use a single shadow map only when its receiver region is genuinely bounded. For large moving views, make shadow coverage an explicit spatial hierarchy.

Cached clipmap workflow

• Define concentric light-space square levels.
• Snap each level center to its own texel grid.
• Cross-fade adjacent levels in shader space.
• Refresh near levels continuously.
• Cache coarse levels and update them under a frame budget.
• Invalidate intersecting levels when important casters or streamed terrain change.
• Scale normal bias by world-space texel width.

Read references/cached-clipmap-shadows.md before implementing a large-world directional light.

Read the

cached shadow clipmaps

for three light-space square levels, per-level texel snapping, containment

cross-fades, cached coarse updates, scaled bias, and unshadowed outside weight.

Failure conditions

• projection centers move by fractions of a texel;
• shader containment does not match the map's committed center;
• all cascades refresh every frame without evidence;
• coarse levels freeze moving casters indefinitely;
• depth texture samples occur in divergent fragment control flow;
• the same normal bias is used across radically different texel sizes;
• level boundaries become visible under camera motion.

Routing boundary

Use this skill for light-space directional shadow maps. Use

$threejs-screen-space-ambient-occlusion for view-dependent ambient

visibility; AO is not a replacement for cast shadows.