123 lines
3.6 KiB
Rust
123 lines
3.6 KiB
Rust
//! Create a custom material to draw basic lines in 3D
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use bevy::{
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pbr::{MaterialPipeline, MaterialPipelineKey},
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prelude::*,
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reflect::TypeUuid,
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render::{
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mesh::{MeshVertexBufferLayout, PrimitiveTopology},
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render_resource::{
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AsBindGroup, PolygonMode, RenderPipelineDescriptor, ShaderRef,
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SpecializedMeshPipelineError,
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},
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},
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};
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fn main() {
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App::new()
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.add_plugins(DefaultPlugins)
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.add_plugin(MaterialPlugin::<LineMaterial>::default())
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.add_systems(Startup, setup)
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.run();
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}
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fn setup(
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mut commands: Commands,
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mut meshes: ResMut<Assets<Mesh>>,
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mut materials: ResMut<Assets<LineMaterial>>,
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) {
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// Spawn a list of lines with start and end points for each lines
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commands.spawn(MaterialMeshBundle {
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mesh: meshes.add(Mesh::from(LineList {
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lines: vec![
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(Vec3::ZERO, Vec3::new(1.0, 1.0, 0.0)),
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(Vec3::new(1.0, 1.0, 0.0), Vec3::new(1.0, 0.0, 0.0)),
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],
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})),
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transform: Transform::from_xyz(-1.5, 0.0, 0.0),
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material: materials.add(LineMaterial {
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color: Color::GREEN,
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}),
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..default()
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});
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// Spawn a line strip that goes from point to point
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commands.spawn(MaterialMeshBundle {
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mesh: meshes.add(Mesh::from(LineStrip {
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points: vec![
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Vec3::ZERO,
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Vec3::new(1.0, 1.0, 0.0),
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Vec3::new(1.0, 0.0, 0.0),
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],
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})),
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transform: Transform::from_xyz(0.5, 0.0, 0.0),
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material: materials.add(LineMaterial { color: Color::BLUE }),
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..default()
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});
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// camera
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commands.spawn(Camera3dBundle {
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transform: Transform::from_xyz(-2.0, 2.5, 5.0).looking_at(Vec3::ZERO, Vec3::Y),
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..default()
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});
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}
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#[derive(Default, AsBindGroup, TypeUuid, Debug, Clone)]
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#[uuid = "050ce6ac-080a-4d8c-b6b5-b5bab7560d8f"]
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struct LineMaterial {
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#[uniform(0)]
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color: Color,
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}
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impl Material for LineMaterial {
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fn fragment_shader() -> ShaderRef {
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"shaders/line_material.wgsl".into()
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}
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fn specialize(
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_pipeline: &MaterialPipeline<Self>,
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descriptor: &mut RenderPipelineDescriptor,
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_layout: &MeshVertexBufferLayout,
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_key: MaterialPipelineKey<Self>,
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) -> Result<(), SpecializedMeshPipelineError> {
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// This is the important part to tell bevy to render this material as a line between vertices
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descriptor.primitive.polygon_mode = PolygonMode::Line;
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Ok(())
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}
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}
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/// A list of lines with a start and end position
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#[derive(Debug, Clone)]
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pub struct LineList {
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pub lines: Vec<(Vec3, Vec3)>,
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}
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impl From<LineList> for Mesh {
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fn from(line: LineList) -> Self {
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// This tells wgpu that the positions are list of lines
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// where every pair is a start and end point
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let mut mesh = Mesh::new(PrimitiveTopology::LineList);
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let vertices: Vec<_> = line.lines.into_iter().flat_map(|(a, b)| [a, b]).collect();
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mesh.insert_attribute(Mesh::ATTRIBUTE_POSITION, vertices);
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mesh
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}
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}
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/// A list of points that will have a line drawn between each consecutive points
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#[derive(Debug, Clone)]
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pub struct LineStrip {
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pub points: Vec<Vec3>,
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}
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impl From<LineStrip> for Mesh {
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fn from(line: LineStrip) -> Self {
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// This tells wgpu that the positions are a list of points
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// where a line will be drawn between each consecutive point
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let mut mesh = Mesh::new(PrimitiveTopology::LineStrip);
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mesh.insert_attribute(Mesh::ATTRIBUTE_POSITION, line.points);
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mesh
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}
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}
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