# Materials
A `Material` is a render pipeline asset — WGSL shader source plus the fixed-function state (vertex layouts, cull mode, depth, targets) needed to compile it. It follows the same [asset pipeline](./the-asset-pipeline.md) pattern as everything else:
```rust,ignore
fn setup(backend: Read<Backend>, mut materials: Write<Assets<Material>>) {
let handle = Material::new(SHADER_SOURCE)
.with_label("unlit")
.with_vertex_layouts(vec![Vertex::layout()])
.with_entries(vec![/* see Bind Groups and Layouts */])
.with_targets(vec![ColorTargetState {
format: backend.surface_format(),
blend: Some(BlendState::ALPHA_BLENDING),
write_mask: ColorWrites::ALL,
}])
.build_asset("unlit", &mut materials);
}
```
Defaults: `vs_main`/`fs_main` entry points, back-face culling, fill mode, no depth testing, sample count 1. Override with `with_vertex_entry`/`without_vertex_entry`, `with_cull_mode`/`without_cull_mode`, `with_depth`, `with_polygon_mode`, `with_sample_count`.
`ColorTargetState::DEFAULT_TARGET` is a ready-made single opaque `Rgba8Unorm` target, if you don't need custom blending.
## Supplying bind group values: `MaterialInstance`
A `Material` only declares what its bind group *shape* is. The actual textures/samplers/uniforms come from a separate asset, `MaterialInstance` (a type alias for `BindingInstance<Material>`):
```rust,ignore
fn make_instance(mut materials: Write<Assets<Material>>, mut instances: Write<Assets<MaterialInstance>>) {
let material_handle = /* from above */;
MaterialInstance::new(material_handle)
.with_texture("albedo", texture_handle)
.with_sampler("albedo_sampler", SamplerKind::LinearRepeat)
.with_uniform("camera", bytemuck::bytes_of(&camera_data).to_vec())
.build_asset("player_instance", &mut instances);
}
```
Names must match the names given in `with_entries` (see [Bind Groups and Layouts](./bind-groups.md)) — a mismatch fails to build silently (the upload retries forever, since the binding lookup returns `None`). The uploaded `GPUMaterialInstance` gives you `update(name, data)` to overwrite a bound uniform/storage buffer in place, without rebuilding the whole bind group — handy for a per-frame value like a camera matrix.
`.with_uniform`/`.with_storage` build a fresh buffer from raw bytes each time. If you already have a [`Buffer`](./buffers.md) — e.g. one written to by a compute pass — bind it directly with `.with_buffer(name, existing_buffer)` instead; no new buffer is created, so `existing_buffer` must already carry the usage flags (`BufferUsages::UNIFORM`/`::STORAGE`) matching how `name` was declared. `.with_dynamic_buffer(name, existing_dynamic_buffer)` does the same for a [`DynamicBuffer`](./buffers.md#dynamic-buffers) — the target's own entry for `name` must have been declared with `has_dynamic_offset: true` to match.