Trait bevy::sprite::Material2d

source ·

pub trait Material2d: AsBindGroup + Asset + Clone + Sized {
    // Provided methods
    fn vertex_shader() -> ShaderRef { ... }
    fn fragment_shader() -> ShaderRef { ... }
    fn depth_bias(&self) -> f32 { ... }
    fn specialize(
        descriptor: &mut RenderPipelineDescriptor,
        layout: &Hashed<InnerMeshVertexBufferLayout>,
        key: Material2dKey<Self>
    ) -> Result<(), SpecializedMeshPipelineError> { ... }
}

Expand description

Materials are used alongside Material2dPlugin and MaterialMesh2dBundle to spawn entities that are rendered with a specific Material2d type. They serve as an easy to use high level way to render Mesh2dHandle entities with custom shader logic.

Material2ds must implement AsBindGroup to define how data will be transferred to the GPU and bound in shaders. AsBindGroup can be derived, which makes generating bindings straightforward. See the AsBindGroup docs for details.

Example

Here is a simple Material2d implementation. The AsBindGroup derive has many features. To see what else is available, check out the AsBindGroup documentation.


#[derive(AsBindGroup, Debug, Clone, Asset, TypePath)]
pub struct CustomMaterial {
    // Uniform bindings must implement `ShaderType`, which will be used to convert the value to
    // its shader-compatible equivalent. Most core math types already implement `ShaderType`.
    #[uniform(0)]
    color: Color,
    // Images can be bound as textures in shaders. If the Image's sampler is also needed, just
    // add the sampler attribute with a different binding index.
    #[texture(1)]
    #[sampler(2)]
    color_texture: Handle<Image>,
}

// All functions on `Material2d` have default impls. You only need to implement the
// functions that are relevant for your material.
impl Material2d for CustomMaterial {
    fn fragment_shader() -> ShaderRef {
        "shaders/custom_material.wgsl".into()
    }
}

// Spawn an entity using `CustomMaterial`.
fn setup(mut commands: Commands, mut materials: ResMut<Assets<CustomMaterial>>, asset_server: Res<AssetServer>) {
    commands.spawn(MaterialMesh2dBundle {
        material: materials.add(CustomMaterial {
            color: Color::RED,
            color_texture: asset_server.load("some_image.png"),
        }),
        ..Default::default()
    });
}

In WGSL shaders, the material’s binding would look like this:

struct CustomMaterial {
    color: vec4<f32>,
}

@group(2) @binding(0) var<uniform> material: CustomMaterial;
@group(2) @binding(1) var color_texture: texture_2d<f32>;
@group(2) @binding(2) var color_sampler: sampler;