bevy/examples/shader/shader_defs.rs
François d44e86507f Shader defs can now have a value (#5900)
# Objective

- shaders defs can now have a `bool` or `int` value
- `#if SHADER_DEF <operator> 3`
  - ok if `SHADER_DEF` is defined, has the correct type and pass the comparison
  - `==`, `!=`, `>=`, `>`, `<`, `<=` supported
- `#SHADER_DEF` or `#{SHADER_DEF}`
  - will be replaced by the value in the shader code
---

## Migration Guide

- replace `shader_defs.push(String::from("NAME"));` by `shader_defs.push("NAME".into());`
- if you used shader def `NO_STORAGE_BUFFERS_SUPPORT`, check how `AVAILABLE_STORAGE_BUFFER_BINDINGS` is now used in Bevy default shaders
2022-11-21 22:38:29 +00:00

102 lines
3 KiB
Rust

//! A shader that uses "shaders defs", which selectively toggle parts of a shader.
use bevy::{
pbr::{MaterialPipeline, MaterialPipelineKey},
prelude::*,
reflect::TypeUuid,
render::{
mesh::MeshVertexBufferLayout,
render_resource::{
AsBindGroup, RenderPipelineDescriptor, ShaderRef, SpecializedMeshPipelineError,
},
},
};
fn main() {
App::new()
.add_plugins(DefaultPlugins)
.add_plugin(MaterialPlugin::<CustomMaterial>::default())
.add_startup_system(setup)
.run();
}
/// set up a simple 3D scene
fn setup(
mut commands: Commands,
mut meshes: ResMut<Assets<Mesh>>,
mut materials: ResMut<Assets<CustomMaterial>>,
) {
// blue cube
commands.spawn(MaterialMeshBundle {
mesh: meshes.add(Mesh::from(shape::Cube { size: 1.0 })),
transform: Transform::from_xyz(-1.0, 0.5, 0.0),
material: materials.add(CustomMaterial {
color: Color::BLUE,
is_red: false,
}),
..default()
});
// red cube (with green color overridden by the IS_RED "shader def")
commands.spawn(MaterialMeshBundle {
mesh: meshes.add(Mesh::from(shape::Cube { size: 1.0 })),
transform: Transform::from_xyz(1.0, 0.5, 0.0),
material: materials.add(CustomMaterial {
color: Color::GREEN,
is_red: true,
}),
..default()
});
// camera
commands.spawn(Camera3dBundle {
transform: Transform::from_xyz(-2.0, 2.5, 5.0).looking_at(Vec3::ZERO, Vec3::Y),
..default()
});
}
impl Material for CustomMaterial {
fn fragment_shader() -> ShaderRef {
"shaders/shader_defs.wgsl".into()
}
fn specialize(
_pipeline: &MaterialPipeline<Self>,
descriptor: &mut RenderPipelineDescriptor,
_layout: &MeshVertexBufferLayout,
key: MaterialPipelineKey<Self>,
) -> Result<(), SpecializedMeshPipelineError> {
if key.bind_group_data.is_red {
let fragment = descriptor.fragment.as_mut().unwrap();
fragment.shader_defs.push("IS_RED".into());
}
Ok(())
}
}
// This is the struct that will be passed to your shader
#[derive(AsBindGroup, TypeUuid, Debug, Clone)]
#[uuid = "f690fdae-d598-45ab-8225-97e2a3f056e0"]
#[bind_group_data(CustomMaterialKey)]
pub struct CustomMaterial {
#[uniform(0)]
color: Color,
is_red: bool,
}
// This key is used to identify a specific permutation of this material pipeline.
// In this case, we specialize on whether or not to configure the "IS_RED" shader def.
// Specialization keys should be kept as small / cheap to hash as possible,
// as they will be used to look up the pipeline for each drawn entity with this material type.
#[derive(Eq, PartialEq, Hash, Clone)]
pub struct CustomMaterialKey {
is_red: bool,
}
impl From<&CustomMaterial> for CustomMaterialKey {
fn from(material: &CustomMaterial) -> Self {
Self {
is_red: material.is_red,
}
}
}