Hair · Berlenga

Fibre shading (BaseMaterial3D Hair section, rendering/pathtracing/hair): Chiang hair model under path tracing, melanin colour, on shells, cards and strands; mask for single-material characters.
Strand grooms (HairGroom, HairMesh): grown on a scalp mesh or loaded from a HAIR file.
Moving strand hair (PhysXHair3D): AMD TressFX’s simulation on GPU compute, guide and follow strands, velocity shock propagation, wind with gusts and turbulence, collision spheres.
Raster strands (TressFX coverage): blended and sorted far to near on the GPU each frame; smooth without TAA or MSAA, and the hair shadows itself.
Raster hair shading (PhysXHair3D.hair_shading): Marschner model as Unreal evaluates it, with multiple scattering and light through the strands in shadow maps, so backlit hair glows.
Distance LOD (PhysXHair3D: lod_enabled, lod_start_distance, lod_end_distance, lod_strand_ratio): far away, fewer and wider strands with the same look; simulation and path tracing keep every strand.
Body collision (PhysXHair3D: collision_body, collision_cell_size): strands collide with a body mesh, skinned or not, through a distance field built on the GPU every frame.
Hair volume (volume_enabled, volume_friction, volume_stiffness): strands push and drag on each other through a density grid, so hair keeps its volume.
Deep opacity shadows (PhysXHair3D.deep_shadows, on with hair_shading): raster strands shadow themselves in depth, calibrated against the path tracer.
Motion vectors for strands: TAA, FSR 2 and DLSS follow moving hair instead of smearing it; shaders get PREVIOUS_FRAME and render_mode alpha_motion_vectors.
Custom hair shaders: HAIR, HAIR_ABSORPTION, HAIR_ROUGHNESS outputs; hair_strands and hair_cards render modes; IN_PATH_TRACER built-in.

Images#

Hair-shaded spheres and cards: raster, path traced, sun behind, cards backlit

Fibre shading: fibre highlights and a bright rim against the sun.

Strand hair grooms: raster, path traced, and path traced with the sun behind

Strand hair: per-fibre colour and a backlit rim.

Simulated strand hair blown by gusting wind, raster

Moving strand hair: the groom streams and flutters in gusting wind.

Raster strand hair: older soft strands, then sharp sorted strands

Raster strands: sorted and blended with no AA; each strand is drawn at its real width, so the groom stays sharp.

Backlit strand hair in raster with Marschner shading

Raster hair shading: backlit, the strands glow warm.

Distant strand hair: all strands, then distance LOD

Distance LOD: fewer, wider strands far away, with the same look.

Strand hair over rounded shoulders: spheres only, shoulders as the collision body, skinned to a tilted bone

Body collision: with spheres only the hair sinks into the shoulders; with the shoulders as the body it drapes over them, also when skinned and tilted.

Strand hair shaking and in wind, hair volume off and on

Hair volume: with it on, the hair stays full instead of collapsing into a flat sheet.

Moving strand hair: motion vectors before and after, then TAA before and after

Motion vectors: before, only part of the hair reports its motion; after, every strand does.

Strand hair with deep opacity shadows in raster, and path traced

Deep opacity shadows: raster darkens the hair with depth like the path tracer; path tracing shows more fuzz at the edges.