2bf481c03b
# Objective The first part of #10569, split up from #11007. The goal is to implement meshing support for Bevy's new geometric primitives, starting with 2D primitives. 3D meshing will be added in a follow-up, and we can consider removing the old mesh shapes completely. ## Solution Add a `Meshable` trait that primitives need to implement to support meshing, as suggested by the [RFC](https://github.com/bevyengine/rfcs/blob/main/rfcs/12-primitive-shapes.md#meshing). ```rust /// A trait for shapes that can be turned into a [`Mesh`]. pub trait Meshable { /// The output of [`Self::mesh`]. This can either be a [`Mesh`] /// or a builder used for creating a [`Mesh`]. type Output; /// Creates a [`Mesh`] for a shape. fn mesh(&self) -> Self::Output; } ``` This PR implements it for the following primitives: - `Circle` - `Ellipse` - `Rectangle` - `RegularPolygon` - `Triangle2d` The `mesh` method typically returns a builder-like struct such as `CircleMeshBuilder`. This is needed to support shape-specific configuration for things like mesh resolution or UV configuration: ```rust meshes.add(Circle { radius: 0.5 }.mesh().resolution(64)); ``` Note that if no configuration is needed, you can even skip calling `mesh` because `From<MyPrimitive>` is implemented for `Mesh`: ```rust meshes.add(Circle { radius: 0.5 }); ``` I also updated the `2d_shapes` example to use primitives, and tweaked the colors to have better contrast against the dark background. Before:  After:  Here you can see the UVs and different facing directions: (taken from #11007, so excuse the 3D primitives at the bottom left)  --- ## Changelog - Added `bevy_render::mesh::primitives` module - Added `Meshable` trait and implemented it for: - `Circle` - `Ellipse` - `Rectangle` - `RegularPolygon` - `Triangle2d` - Implemented `Default` and `Copy` for several 2D primitives - Updated `2d_shapes` example to use primitives - Tweaked colors in `2d_shapes` example to have better contrast against the (new-ish) dark background --------- Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
65 lines
1.9 KiB
Rust
65 lines
1.9 KiB
Rust
//! Shows how to render simple primitive shapes with a single color.
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use bevy::{prelude::*, sprite::MaterialMesh2dBundle};
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fn main() {
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App::new()
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.add_plugins(DefaultPlugins)
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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<ColorMaterial>>,
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) {
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commands.spawn(Camera2dBundle::default());
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// Circle
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commands.spawn(MaterialMesh2dBundle {
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mesh: meshes.add(Circle { radius: 50.0 }).into(),
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material: materials.add(Color::VIOLET),
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transform: Transform::from_translation(Vec3::new(-225.0, 0.0, 0.0)),
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..default()
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});
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// Ellipse
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commands.spawn(MaterialMesh2dBundle {
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mesh: meshes.add(Ellipse::new(25.0, 50.0)).into(),
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material: materials.add(Color::TURQUOISE),
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transform: Transform::from_translation(Vec3::new(-100.0, 0.0, 0.0)),
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..default()
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});
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// Rectangle
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commands.spawn(MaterialMesh2dBundle {
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mesh: meshes.add(Rectangle::new(50.0, 100.0)).into(),
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material: materials.add(Color::LIME_GREEN),
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transform: Transform::from_translation(Vec3::new(0.0, 0.0, 0.0)),
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..default()
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});
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// Hexagon
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commands.spawn(MaterialMesh2dBundle {
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mesh: meshes.add(RegularPolygon::new(50.0, 6)).into(),
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material: materials.add(Color::YELLOW),
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transform: Transform::from_translation(Vec3::new(125.0, 0.0, 0.0)),
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..default()
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});
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// Triangle
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commands.spawn(MaterialMesh2dBundle {
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mesh: meshes
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.add(Triangle2d::new(
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Vec2::Y * 50.0,
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Vec2::new(-50.0, -50.0),
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Vec2::new(50.0, -50.0),
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))
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.into(),
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material: materials.add(Color::ORANGE),
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transform: Transform::from_translation(Vec3::new(250.0, 0.0, 0.0)),
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..default()
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});
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}
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