A material that draws with a shader graph

A shader graph can be two different things, and only one of them can be drawn.

ShaderGraphKind.Standalone is a whole shader — its own worldViewProjection, its own vertex stage, a float4 returned from a fragment entry point. Master/Unlit, Master/Sprite and Master/PBR make one. It is readable, it is what a preview thumbnail draws, and an author can hand it to raven compile.

ShaderGraphKind.Surface is a material feature: shader N : IMaterialSurface, with no stages, no entry point and no return. SurfaceMasterNode — Master/Surface on the menu — makes one.

The master decides which, and that is the only structural decision a node makes.

⚠ A standalone shader cannot be put on a mesh, and the reason is not that something is missing. A draw in this engine binds a transform record, a light cluster, a shadow atlas and a bindless texture table, under names that come from the pass the material is composed into. A shader that declares its own worldViewProjection is not a smaller version of that; it is a different program, and drawing with one would mean a second render feature, a second pass and a second way of being lit.

An IMaterialSurface is exactly what an IMaterialFeature names. So a graph-authored material is a material with one more feature in its list — GraphSurfaceFeature — composed into CompositeSurface beside MetalRoughnessSurface and the rest. Everything after that is the path every hand-authored material already takes.

⚠ A feature is composed into a pass it has never seen, so it may only read MaterialData. uv resolves to d.uv and a world normal to d.tangentFrame.normal. A world position and a vertex colour are not on that struct at all, and a graph that reads one is refused with SG0004 rather than given the origin or white — both of which compile, draw, and produce a surface lit as though the graph said something it did not.

Add a Master/Surface node, wire the channels, and save. Then name the graph as a feature on a .vxmat.

ShaderGraphSources is what turns the file into Raven: it compiles every .vxshadergraph under Assets/ and hands the text to whichever compilation wants it — EditorEffects in the editor, ShaderBuildRunner in vixen build. ⚠ Nothing is written to disk. A generated .rvn beside its graph would acquire a .meta, an address and a place in the browser, be committed by somebody, and then be silently overwritten by the next import.

ShaderGraphImporter claims the extension and writes no artefact. What a graph produces is source, and source is not content; the importer exists to compile the graph and report its diagnostics beside the file that caused them, on MaterialImporter's terms.

⚠ A graph that will not compile contributes nothing rather than its text. Unparseable source in a shared compilation refuses every material in the project, so one graph an author is halfway through would take the whole editor's shading with it. The diagnostics come back on ShaderGraphSourceFile.Diagnostics; EditorEffects.GraphRefusals keeps them apart from the refusal that means "there are no effects at all".

Textures are slots, not bindings. A standalone graph declares albedo: Texture2D and albedoSampler: Sampler and owns them. A surface declares albedoIndex: uint and indexes MaterialTextures's shared table. ShaderGraphMap carries the albedo ⇄ albedoIndex pairing a host feeds MaterialRenderFeature.TextureIndices — both halves, explicitly, because a runtime reading a baked material never ran the generator that spells the convention.

⚠ The table is indexed directly rather than through SampleSurface, which samples at d.uv unconditionally — so a graph with a Tiling and Offset node would otherwise compile, draw, and sample somewhere the author did not ask for.

Compile a graph and turn it into the feature a material composes:

ShaderGraphMaterial.Values(source) is the narrower list an inspector offers a person: every property the graph declares except the texture slots, which a host overwrites from the bindless table every frame.

Give it the values a material sets, by the names the graph declares:

And read a project's graphs the way both shader compilations do:

• Shader-graph preview thumbnails — the other consumer of the compiler, and the one that wants a standalone shader rather than a surface.
• Graph diagnostics — how a complaint about generated text names the node an author can select.
• Meshes and materials, type by type — where GraphSurfaceFeature sits among the features it is composed beside.