Glossary

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Alpha-clipped caster: A caster whose material discards pixels below an alpha cutoff, such as a grate or leaf card. See Transparent and Translucent Casters.

Backend: Where shadow volumes are generated, either the CPU (Burst jobs) or the GPU (compute shaders). See Performance.

Carmack's Reverse: Another name for z-fail stencil shadows.

Caster: A renderer that casts a stencil shadow. See Shadow Casters.

Caster atlas: A shared texture of light-space tiles that gives alpha-clipped and transparent casters their holes and opacity in Textured mode. See Caster Atlas.

Composite: The Overlay-mode pass that darkens shadowed pixels toward Shadow Color.

Discovery: The periodic scene scan that finds casters. See Caster discovery.

Extrusion: Stretching a caster's silhouette away from the light to form its shadow volume.

GPU fallback: A caster the GPU backend can't handle being generated on the CPU instead. See GPU fallback.

GPU-deformed mesh: A Mesh Renderer whose vertices are rewritten on the GPU, for example by a compute shader. See Shadow Casters.

Lighting mode: How shadows combine with lighting, either Overlay or URP Lighting. See Lighting modes.

Receiver: A surface shadows fall on.

Receiver sizing: Sizing caster atlas tiles for the distance to the surfaces a shadow falls on. See Tile sizing.

Scissor: The screen rectangle a caster's stencil work is limited to.

Self-shadow cancellation: Clearing a caster's own volume from its visible surface, so it shows only shadows from other casters. See Receivers and Materials.

Shadow volume: A closed mesh enclosing the space a caster blocks from a light. See How Stencil Shadow Volumes Work.

Silhouette edge: An edge between a triangle facing the light and one facing away.

Stencil mask: The low stencil bits the feature owns. See The owned stencil bits.

Terminator: The line on a surface where it turns from facing the light to facing away.

Topology: A mesh's edge adjacency, needed to find silhouette edges. See Mesh Topology.

Transmittance: The fraction and color of light a transparent surface lets through.

Union bit: The highest owned stencil bit, accumulating every caster's shadow.

Weld tolerance: The distance within which vertex positions are joined when building topology.

Z-fail: Counting shadow volume faces hidden behind scene geometry, which stays correct with the camera inside a volume.