Persistent footprints, trenches and displaced berms carved into a snow field at runtime, with the surface, lighting and audio all responding to the deformation. Built on Epic's Game Animation Sample to answer one question: what does it take to make a character look like they are actually moving through deep snow? The world has to record where the character has been.
Trench depth, berm height, disturbed tint, sparkle falloff, blur radius and the border taper are all exposed as named parameters rather than buried constants, so the look can be pushed without opening the material graph.
The graph itself was authored through Python remote execution against the live editor, with a layout-and-comment pass afterwards: the 186 expressions sit in 17 titled lanes rather than stacked on one another. A reachability proof - the exec-reachable set plus its transitive data ancestors - removed 135 of 237 nodes from a snow Blueprint function without touching a live wire.
A dense mesh patch is conformed to the landscape by a baked height texture read in World Position Offset, so its geometry follows the terrain exactly. The patch is fixed in world space rather than re-centred on the character, which keeps the surface still under the lighting. An orthographic scene capture above the character drives a ping-ponged pair of render targets that accumulate deformation history; the material subtracts that history from the conformed height to cut trenches, and adds a rim term to push snow up along the trench walls as displaced berms.
Footfalls are stamped into the accumulation buffer through a custom HLSL pass that writes a directional, softened boot print, so prints read as compressed snow rather than punched holes.
The same depth signal drives everything downstream, so the shading always agrees with the geometry. Trench interiors desaturate, roughen and occlude, because disturbed snow reads differently from fresh snow, while berm crests pick up a separate tint so the displaced ridge catches light. Trampled-snow textures blend in triplanar on the trench floor and its walls, keyed off a slope term derived from a central-difference read of the depth buffer.
A view-dependent sparkle pass drives Emissive off the sun direction and a noise field, fading with distance. A read-time blur softens the surface without smearing the history buffer itself, and a radial taper fades the patch back to landscape height at its border so the moving patch never shows a seam against the terrain.
NS_SnowSpray throws a per-footfall puff along the direction of travel, its spawn rotation built from the pawn's flattened velocity. NS_SnowWade is a continuous trail-filling effect, gated by a proximity test against the snow patch so it never spawns in other levels. Footstep audio is a single source file cut into individual steps, played on an edge-triggered gate driven by which foot is planted, and gated to the patch the same way. NS_Snowfall and a PCG-scattered winter forest with tuned canopy wind sit behind all of it, matched to a looping wind ambience.