bevy/examples/custom_shader.rs

use bevy::{
    prelude::*,
    render::{
        render_graph::{
            resource_name, resource_providers::UniformResourceProvider, PipelineDescriptor,
        },
        Shader, ShaderStage,
    },
};

use bevy_derive::Uniforms;

#[derive(Uniforms, Default)]
struct MyMaterial {
    pub color: Vec4,
    #[uniform(ignore, shader_def)]
    pub always_red: bool,
}

fn main() {
    AppBuilder::new()
        .add_defaults()
        .setup_world(setup)
        .setup_render_graph(|builder, pipeline_storage, shader_storage| {
            builder
                .add_resource_provider(Box::new(UniformResourceProvider::<MyMaterial>::new()))
                .add_pipeline_to_pass(
                    resource_name::pass::MAIN,
                    pipeline_storage,
                    PipelineDescriptor::build(
                        shader_storage,
                        Shader::from_glsl(
                            ShaderStage::Vertex,
                            r#"
                                #version 450
                                layout(location = 0) in vec4 a_Pos;
                                layout(location = 0) out vec4 v_Position;
                                layout(set = 0, binding = 0) uniform Camera {
                                    mat4 ViewProj;
                                };
                                layout(set = 1, binding = 0) uniform Object {
                                    mat4 Model;
                                };
                                void main() {
                                    v_Position = Model * a_Pos;
                                    gl_Position = ViewProj * v_Position;
                                }
                            "#,
                        ),
                    )
                    .with_fragment_shader(Shader::from_glsl(
                        ShaderStage::Fragment,
                        r#"
                                #version 450
                                layout(location = 0) in vec4 v_Position;
                                layout(location = 0) out vec4 o_Target;
                                layout(set = 1, binding = 1) uniform MyMaterial_color {
                                    vec4 color;
                                };
                                void main() {
                                    o_Target = color;

                                # ifdef MY_MATERIAL_ALWAYS_RED
                                    o_Target = vec4(0.8, 0.0, 0.0, 1.0);
                                # endif
                                }
                        "#,
                    ))
                    .with_standard_config()
                    .build(),
                )
        })
        .run();
}

fn setup(world: &mut World, resources: &mut Resources) {
    let mut mesh_storage = resources.get_mut::<AssetStorage<Mesh>>().unwrap();
    let cube_handle = mesh_storage.add(Mesh::load(MeshType::Cube));

    world
        .build()
        // cube
        .add_entity(MeshMaterialEntity::<MyMaterial> {
            mesh: cube_handle,
            renderable: Renderable {
                pipelines: vec![Handle::new(2)], // TODO: make this pipeline assignment cleaner
                ..Default::default()
            },
            material: MyMaterial {
                color: Vec4::new(0.0, 0.8, 0.0, 1.0),
                always_red: false,
            },
            translation: Translation::new(-2.0, 0.0, 0.0),
            ..Default::default()
        })
        // cube
        .add_entity(MeshMaterialEntity::<MyMaterial> {
            mesh: cube_handle,
            renderable: Renderable {
                pipelines: vec![Handle::new(2)], // TODO: make this pipeline assignment cleaner
                ..Default::default()
            },
            material: MyMaterial {
                color: Vec4::new(0.0, 0.0, 0.0, 1.0),
                always_red: true,
            },
            translation: Translation::new(2.0, 0.0, 0.0),
            ..Default::default()
        })
        // camera
        .add_entity(CameraEntity {
            camera: Camera::new(CameraType::Projection {
                fov: std::f32::consts::PI / 4.0,
                near: 1.0,
                far: 1000.0,
                aspect_ratio: 1.0,
            }),
            active_camera: ActiveCamera,
            local_to_world: LocalToWorld(Mat4::look_at_rh(
                Vec3::new(3.0, 8.0, 5.0),
                Vec3::new(0.0, 0.0, 0.0),
                Vec3::new(0.0, 0.0, 1.0),
            )),
        })
        .build();
}