Joona Aalto 2bf481c03b Add Meshable trait and implement meshing for 2D primitives (#11431) ... # 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>		2024-01-29 16:47:47 +00:00
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src	Add Meshable trait and implement meshing for 2D primitives (#11431)	2024-01-29 16:47:47 +00:00
Cargo.toml	Add more constructors and math helpers for primitive shapes (#10632)	2024-01-29 16:04:51 +00:00