Procedural materials (node-based)

A procedural material is built from a graph of connected nodes, each doing one small operation (make a shape, blur, warp, blend, colour), instead of being painted pixel by pixel. Change a value early in the graph and everything after it updates. Adobe describes Substance 3D Designer as having "a heavy focus on procedural generation, parameterization and non-destructive workflows" (Substance 3D Designer documentation: Substance 3D Designer overview).

"Procedural" describes how the material is made. The result is usually still a set of ordinary textures, used as a tileable, a trim sheet or a decal. See ways to texture an environment.

#Why build materials from nodes

• Non-destructive. Adobe says "you can reverse any action without losing any of your work" (Substance 3D Designer documentation: Substance 3D Designer overview).
• Variants from one graph. Designer lets you "control nearly any aspect of a texture through a single slider or dropdown" (Substance 3D Designer documentation: Substance 3D Designer overview). Nathan Mackenzie describes a rock material that can be changed "with just a few sliders and in just a few seconds" and reused from jungle to tropical scenes (80 Level: Advanced Materials with Substance).
• Consistency across a team. Shared graphs and node libraries keep materials in one style. Naughty Dog's GDC 2016 talk covers the goals and evolution of the studio's Substance pipeline on Uncharted 4, from adopting physically based rendering to managing content (GDC Vault: Texturing Uncharted 4: a matter of Substance).
• Resolution independence. The graph can be re-exported at any resolution.

#How a graph is structured

Most graphs follow the same logic:

1. Pattern: shapes placed by a scatter or tile node. Daniel Thiger's fundamentals course is built around the Tile Sampler, Designer's main scatter node (Gumroad: Tutorial | Fundamentals Part 1: Pattern…).
2. Height: pattern plus warps and noises, from large forms to small. Margot Casiro: the heightmap is "what will drive absolutely everything else" (80 Level: 001AGT: Learning Substance Designer…).
3. Masks: extracted from the height at each stage.
4. Outputs: colour via gradient maps, roughness via levels, normal and AO from height.
5. Parameters: the values you want others to change.

Adobe's own First Steps tutorial follows this order, ending with "exposing parameters" and a complete PBR material (Adobe Learn: First Steps with Substance 3D Designer).

#The tools

Designer, InstaMAT and Material Maker are texture generators: they output images. Blender's and Unreal's graphs are shaders: they compute the surface when it is rendered. The difference affects performance in games.

#Bake to textures, or compute in the shader?

A texture generator's graph can be hundreds of nodes, because you only pay the cost once, when you export. A shader graph runs for every pixel on screen every frame, so it has to stay cheap. See shaders for artists and master materials and instances.

So the usual split is:

• Author the material in Designer, InstaMAT or Material Maker and export textures.
• Combine and vary those textures in the engine's material graph: tiling, blending layers, vertex colour masks, detail maps and macro variation, triplanar and world-aligned mapping.

Blender's procedural textures work in Blender renders, but game engines cannot read them. Bake them to image textures before export (see baking).

#SBSAR files and parameters

Designer publishes graphs as SBSAR (Substance Archive) files, which Adobe calls "compiled, optimized" files that calculate faster and are easy to share, adding "you'll export to SBSAR if the target supports it" (Substance 3D Designer documentation: Substance 3D Designer overview).

An SBSAR keeps the parameters you exposed. Other apps show them as controls:

• Unreal Engine: Adobe's plugin lets you "Tweak SBSARs directly in Unreal Engine" (adobe.com: Substance 3D for Unreal Engine).
• Unity: parameters "are accessible on the Substance Graph Object", the control type matches the parameter type, and a Random Seed button creates "a new result for the computed texture based on the seed value" (Substance 3D integrations documentation: Changing parameters).
• Substance 3D Painter: SBSAR materials appear as layers with their sliders.

#Further reading and watching