Unreal Materials 101

3.1The Pbr Inputs That Matter

Unreal's default shading model is metallic/roughness PBR. Ninety percent of surfaces use five pins: Base Color (no lighting baked in), Metallic (0 or 1, rarely between), Roughness (where all the surface character lives), Normal, and Ambient Occlusion. Emissive adds glow; Opacity/Opacity Mask appear only in translucent/masked blend modes - both cost extra.

3.2Reading The Material Graph

Placeholder with instructions to screenshot a master material in the material editor — placeholder - a master material graph

The graph compiles to HLSL - every node is shader code, and every pixel on screen pays for it. The core vocabulary: TextureSample, Multiply/Lerp/Add, TexCoord for tiling, Fresnel for rim effects, and Time + Panner for animation. Scalar and Vector Parameters (instead of constants) are what make instancing possible - name them properly from the start.

3.3Master Materials And Instances

Diagram of a master material with four material instances — fig 13 - one master, many instances

The material habit that saves the most pain: artists should almost never create materials - they create Material Instances of a small set of master materials owned by tech art.

A master material (e.g. M_Environment_Master) defines the logic once: texture parameters, tiling controls, detail normal blending, wind, tint.
An instance (MI_Rock_01) swaps parameters with zero recompilation - instant iteration for artists.
Static switches in the master let instances toggle features - but every switch combination compiles a separate shader permutation. A master with ten switches can quietly become thousands of shaders. Budget your switches.

The TA's deliverable

A well-designed master material library - 3 to 8 masters covering environment, props, glass, foliage, decals - is one of the highest-use things a TA ships on any project.

3.4What Costs What

Feature	Cost reality
Opaque material, few samplers	The happy path - cheap
Masked	Moderate - disables early-Z optimizations where used
Translucent	Expensive - every overlapping layer shades the same pixel again (overdraw)
Two-sided	Doubles rasterization work - reserve for foliage/cloth
World Position Offset	Vertex cost on everything using it, plus shadow/culling side-effects
Many texture samplers	16+ samplers stalls; pack channels (ORM) instead

Check your work with the Shader Complexity view mode and the stats panel in the material editor. The deep dive lives in Performance -> Materials & Shaders.