Material Properties
- Material Domain: "allows you to define how you will use the Material. Certain Material uses (such as decals) require additional instructions for the render engine". Options: Surface (default; object surfaces), Deferred Decal, Light Function, Volume (3D volume attributes), Post Process, User Interface (UMG or Slate), Virtual Texture (Runtime Virtual Texture).
- Two Sided: normal flipped on back faces; foliage; doesn't work correctly with static lighting (single lightmap UV).
- Use Material Attributes for layered materials. Dithered LOD Transition; Dither Opacity Mask (with TAA, limited translucency supporting all lighting). Fully Rough saves instructions and a sampler.
- Translucency Lighting Mode: Volumetric NonDirectional (cheapest, ignores normal), Volumetric Directional, Volumetric PerVertex (Non)Directional (much cheaper pixel cost), Surface Translucency Volume (blurry, low cost; glass/water; diffuse only), Surface Forward Shading (specular from local lights, most expensive). Responsive AA for small moving particles; Translucency Pass (separate translucency, not affected by DOF); Disable Depth Test makes rendering significantly slower.
- Usage flags (Surface domain only): Used with Skeletal Mesh, Particle Sprites, Niagara Sprites/Ribbons/Mesh Particles, Morph Targets, Instanced Static Meshes, Geometry Collections, Landscape, UI etc.; compile special versions; set automatically in editor (must save material); missing flag → default world grid material used in game with log message. Mesh particles flag increases shader compile time and memory.
- Post Process: Blendable Location (before/after tonemapping), Blendable Priority, Is Blendable, stencil test against Custom Depth/Stencil.
- Refraction Method: Index Of Refraction (physical; reads outside scene color; poor for large surfaces like water), Pixel Normal Offset (non-physical; good for water), 2D Offset.
- Max World Position Offset Displacement: clamps WPO and pushes bounds out; important for Nanite clusters culled individually on GPU; Out of Bounds Pixels show flag.