materialVertexShader method
The vertex shader this material supplies for a geometry's variant
('unskinned' / 'skinned' for the color pass, 'depth' for the
position-only depth/shadow pass; see Geometry.materialVertexVariant),
or null to use the engine's standard vertex shader for the geometry.
The base class supplies none, so drawing is unchanged. A .fmat with a
vertex { } block (see PreprocessedMaterial) returns the matching
generated variant, which the encoder pairs with this material's fragment
shader.
Implementation
@override
gpu.Shader? materialVertexShader(String variant) => _vertexShaders?[variant];