Common MeshBuilder trait (#13411)

# Objective

- All `ShapeMeshBuilder`s have some methods/implementations in common.
These are `fn build(&self) -> Mesh` and this implementation:
```rust
impl From<ShapeMeshBuilder> for Mesh { 
    fn from(builder: ShapeMeshBuilder) -> { 
        builder.build() 
    } 
}
``` 

- For the sake of consistency, these can be moved into a shared trait

## Solution

- Add `trait MeshBuilder` containing a `fn build(&self) -> Mesh` and
implementing `MeshBuilder for ShapeMeshBuilder`
- Implement `From<T: MeshBuilder> for Mesh`

## Migration Guide

- When calling `.build()` you need to import
`bevy_render::mesh::primitives::MeshBuilder`

crates/bevy_render/src/lib.rs

@@ -43,7 +43,7 @@ pub mod prelude {
             Camera, ClearColor, ClearColorConfig, OrthographicProjection, PerspectiveProjection,
             Projection,
         },
-        mesh::{morph::MorphWeights, primitives::Meshable, Mesh},
+        mesh::{morph::MorphWeights, primitives::MeshBuilder, primitives::Meshable, Mesh},
         render_resource::Shader,
         spatial_bundle::SpatialBundle,
         texture::{image_texture_conversion::IntoDynamicImageError, Image, ImagePlugin},

crates/bevy_render/src/mesh/primitives/dim2.rs

@@ -4,7 +4,7 @@ use crate::{
     render_asset::RenderAssetUsages,
 };
 
-use super::Meshable;
+use super::{MeshBuilder, Meshable};
 use bevy_math::primitives::{
     Annulus, Capsule2d, Circle, Ellipse, Rectangle, RegularPolygon, Triangle2d, Triangle3d,
     WindingOrder,
@@ -48,9 +48,10 @@ impl CircleMeshBuilder {
         self.resolution = resolution;
         self
     }
+}
 
-    /// Builds a [`Mesh`] based on the configuration in `self`.
+impl MeshBuilder for CircleMeshBuilder {
-    pub fn build(&self) -> Mesh {
+    fn build(&self) -> Mesh {
         RegularPolygon::new(self.circle.radius, self.resolution).mesh()
     }
 }
@@ -72,12 +73,6 @@ impl From<Circle> for Mesh {
     }
 }
 
-impl From<CircleMeshBuilder> for Mesh {
-    fn from(circle: CircleMeshBuilder) -> Self {
-        circle.build()
-    }
-}
-
 impl Meshable for RegularPolygon {
     type Output = Mesh;
 
@@ -133,9 +128,10 @@ impl EllipseMeshBuilder {
         self.resolution = resolution;
         self
     }
+}
 
-    /// Builds a [`Mesh`] based on the configuration in `self`.
+impl MeshBuilder for EllipseMeshBuilder {
-    pub fn build(&self) -> Mesh {
+    fn build(&self) -> Mesh {
         let mut indices = Vec::with_capacity((self.resolution - 2) * 3);
         let mut positions = Vec::with_capacity(self.resolution);
         let normals = vec![[0.0, 0.0, 1.0]; self.resolution];
@@ -188,12 +184,6 @@ impl From<Ellipse> for Mesh {
     }
 }
 
-impl From<EllipseMeshBuilder> for Mesh {
-    fn from(ellipse: EllipseMeshBuilder) -> Self {
-        ellipse.build()
-    }
-}
-
 /// A builder for creating a [`Mesh`] with an [`Annulus`] shape.
 pub struct AnnulusMeshBuilder {
     /// The [`Annulus`] shape.
@@ -229,9 +219,10 @@ impl AnnulusMeshBuilder {
         self.resolution = resolution;
         self
     }
+}
 
-    /// Builds a [`Mesh`] based on the configuration in `self`.
+impl MeshBuilder for AnnulusMeshBuilder {
-    pub fn build(&self) -> Mesh {
+    fn build(&self) -> Mesh {
         let inner_radius = self.annulus.inner_circle.radius;
         let outer_radius = self.annulus.outer_circle.radius;
 
@@ -306,12 +297,6 @@ impl From<Annulus> for Mesh {
     }
 }
 
-impl From<AnnulusMeshBuilder> for Mesh {
-    fn from(builder: AnnulusMeshBuilder) -> Self {
-        builder.build()
-    }
-}
-
 impl Meshable for Triangle2d {
     type Output = Mesh;
 
@@ -423,9 +408,10 @@ impl Capsule2dMeshBuilder {
         self.resolution = resolution;
         self
     }
+}
 
-    /// Builds a [`Mesh`] based on the configuration in `self`.
+impl MeshBuilder for Capsule2dMeshBuilder {
-    pub fn build(&self) -> Mesh {
+    fn build(&self) -> Mesh {
         // The resolution is the number of vertices for one semicircle
         let resolution = self.resolution as u32;
         let vertex_count = 2 * self.resolution;
@@ -517,12 +503,6 @@ impl From<Capsule2d> for Mesh {
     }
 }
 
-impl From<Capsule2dMeshBuilder> for Mesh {
-    fn from(capsule: Capsule2dMeshBuilder) -> Self {
-        capsule.build()
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use bevy_math::primitives::RegularPolygon;

crates/bevy_render/src/mesh/primitives/dim3/capsule.rs

@@ -1,5 +1,5 @@
 use crate::{
-    mesh::{Indices, Mesh, Meshable},
+    mesh::{Indices, Mesh, MeshBuilder, Meshable},
     render_asset::RenderAssetUsages,
 };
 use bevy_math::{primitives::Capsule3d, Vec2, Vec3};
@@ -91,9 +91,10 @@ impl Capsule3dMeshBuilder {
         self.uv_profile = uv_profile;
         self
     }
+}
 
-    /// Builds a [`Mesh`] based on the configuration in `self`.
+impl MeshBuilder for Capsule3dMeshBuilder {
-    pub fn build(&self) -> Mesh {
+    fn build(&self) -> Mesh {
         // code adapted from https://behreajj.medium.com/making-a-capsule-mesh-via-script-in-five-3d-environments-c2214abf02db
         let Capsule3dMeshBuilder {
             capsule,
@@ -437,9 +438,3 @@ impl From<Capsule3d> for Mesh {
         capsule.mesh().build()
     }
 }
-
-impl From<Capsule3dMeshBuilder> for Mesh {
-    fn from(capsule: Capsule3dMeshBuilder) -> Self {
-        capsule.build()
-    }
-}

crates/bevy_render/src/mesh/primitives/dim3/cone.rs

@@ -2,7 +2,7 @@ use bevy_math::{primitives::Cone, Vec3};
 use wgpu::PrimitiveTopology;
 
 use crate::{
-    mesh::{Indices, Mesh, Meshable},
+    mesh::{Indices, Mesh, MeshBuilder, Meshable},
     render_asset::RenderAssetUsages,
 };
 
@@ -43,9 +43,10 @@ impl ConeMeshBuilder {
         self.resolution = resolution;
         self
     }
+}
 
-    /// Builds a [`Mesh`] based on the configuration in `self`.
+impl MeshBuilder for ConeMeshBuilder {
-    pub fn build(&self) -> Mesh {
+    fn build(&self) -> Mesh {
         let half_height = self.cone.height / 2.0;
 
         // `resolution` vertices for the base, `resolution` vertices for the bottom of the lateral surface,
@@ -157,17 +158,11 @@ impl From<Cone> for Mesh {
     }
 }
 
-impl From<ConeMeshBuilder> for Mesh {
-    fn from(cone: ConeMeshBuilder) -> Self {
-        cone.build()
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use bevy_math::{primitives::Cone, Vec2};
 
-    use crate::mesh::{Mesh, Meshable, VertexAttributeValues};
+    use crate::mesh::{primitives::MeshBuilder, Mesh, Meshable, VertexAttributeValues};
 
     /// Rounds floats to handle floating point error in tests.
     fn round_floats<const N: usize>(points: &mut [[f32; N]]) {

crates/bevy_render/src/mesh/primitives/dim3/cylinder.rs

@@ -2,7 +2,7 @@ use bevy_math::primitives::Cylinder;
 use wgpu::PrimitiveTopology;
 
 use crate::{
-    mesh::{Indices, Mesh, Meshable},
+    mesh::{Indices, Mesh, MeshBuilder, Meshable},
     render_asset::RenderAssetUsages,
 };
 
@@ -58,9 +58,10 @@ impl CylinderMeshBuilder {
         self.segments = segments;
         self
     }
+}
 
-    /// Builds a [`Mesh`] based on the configuration in `self`.
+impl MeshBuilder for CylinderMeshBuilder {
-    pub fn build(&self) -> Mesh {
+    fn build(&self) -> Mesh {
         let resolution = self.resolution;
         let segments = self.segments;
 
@@ -176,9 +177,3 @@ impl From<Cylinder> for Mesh {
         cylinder.mesh().build()
     }
 }
-
-impl From<CylinderMeshBuilder> for Mesh {
-    fn from(cylinder: CylinderMeshBuilder) -> Self {
-        cylinder.build()
-    }
-}

crates/bevy_render/src/mesh/primitives/dim3/plane.rs

@@ -2,7 +2,7 @@ use bevy_math::{primitives::Plane3d, Dir3, Quat, Vec2, Vec3};
 use wgpu::PrimitiveTopology;
 
 use crate::{
-    mesh::{Indices, Mesh, Meshable},
+    mesh::{Indices, Mesh, MeshBuilder, Meshable},
     render_asset::RenderAssetUsages,
 };
 
@@ -65,9 +65,10 @@ impl PlaneMeshBuilder {
         self.plane.half_size = Vec2::new(width, height) / 2.0;
         self
     }
+}
 
-    /// Builds a [`Mesh`] based on the configuration in `self`.
+impl MeshBuilder for PlaneMeshBuilder {
-    pub fn build(&self) -> Mesh {
+    fn build(&self) -> Mesh {
         let rotation = Quat::from_rotation_arc(Vec3::Y, *self.plane.normal);
         let positions = vec![
             rotation * Vec3::new(self.plane.half_size.x, 0.0, -self.plane.half_size.y),
@@ -104,9 +105,3 @@ impl From<Plane3d> for Mesh {
         plane.mesh().build()
     }
 }
-
-impl From<PlaneMeshBuilder> for Mesh {
-    fn from(plane: PlaneMeshBuilder) -> Self {
-        plane.build()
-    }
-}

crates/bevy_render/src/mesh/primitives/dim3/sphere.rs

@@ -1,7 +1,7 @@
 use std::f32::consts::PI;
 
 use crate::{
-    mesh::{Indices, Mesh, Meshable},
+    mesh::{Indices, Mesh, MeshBuilder, Meshable},
     render_asset::RenderAssetUsages,
 };
 use bevy_math::primitives::Sphere;
@@ -75,19 +75,6 @@ impl SphereMeshBuilder {
         self
     }
 
-    /// Builds a [`Mesh`] according to the configuration in `self`.
-    ///
-    /// # Panics
-    ///
-    /// Panics if the sphere is a [`SphereKind::Ico`] with a subdivision count
-    /// that is greater than or equal to `80` because there will be too many vertices.
-    pub fn build(&self) -> Mesh {
-        match self.kind {
-            SphereKind::Ico { subdivisions } => self.ico(subdivisions).unwrap(),
-            SphereKind::Uv { sectors, stacks } => self.uv(sectors, stacks),
-        }
-    }
-
     /// Creates an icosphere mesh with the given number of subdivisions.
     ///
     /// The number of faces quadruples with each subdivision.
@@ -244,6 +231,21 @@ impl SphereMeshBuilder {
     }
 }
 
+impl MeshBuilder for SphereMeshBuilder {
+    /// Builds a [`Mesh`] according to the configuration in `self`.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the sphere is a [`SphereKind::Ico`] with a subdivision count
+    /// that is greater than or equal to `80` because there will be too many vertices.
+    fn build(&self) -> Mesh {
+        match self.kind {
+            SphereKind::Ico { subdivisions } => self.ico(subdivisions).unwrap(),
+            SphereKind::Uv { sectors, stacks } => self.uv(sectors, stacks),
+        }
+    }
+}
+
 impl Meshable for Sphere {
     type Output = SphereMeshBuilder;
 
@@ -260,9 +262,3 @@ impl From<Sphere> for Mesh {
         sphere.mesh().build()
     }
 }
-
-impl From<SphereMeshBuilder> for Mesh {
-    fn from(sphere: SphereMeshBuilder) -> Self {
-        sphere.build()
-    }
-}

crates/bevy_render/src/mesh/primitives/dim3/torus.rs

@@ -2,7 +2,7 @@ use bevy_math::{primitives::Torus, Vec3};
 use wgpu::PrimitiveTopology;
 
 use crate::{
-    mesh::{Indices, Mesh, Meshable},
+    mesh::{Indices, Mesh, MeshBuilder, Meshable},
     render_asset::RenderAssetUsages,
 };
 
@@ -65,9 +65,10 @@ impl TorusMeshBuilder {
         self.major_resolution = resolution;
         self
     }
+}
 
-    /// Builds a [`Mesh`] according to the configuration in `self`.
+impl MeshBuilder for TorusMeshBuilder {
-    pub fn build(&self) -> Mesh {
+    fn build(&self) -> Mesh {
         // code adapted from http://apparat-engine.blogspot.com/2013/04/procedural-meshes-torus.html
 
         let n_vertices = (self.major_resolution + 1) * (self.minor_resolution + 1);
@@ -158,9 +159,3 @@ impl From<Torus> for Mesh {
         torus.mesh().build()
     }
 }
-
-impl From<TorusMeshBuilder> for Mesh {
-    fn from(torus: TorusMeshBuilder) -> Self {
-        torus.build()
-    }
-}

crates/bevy_render/src/mesh/primitives/mod.rs

@@ -25,12 +25,26 @@ pub use dim2::{CircleMeshBuilder, EllipseMeshBuilder};
 mod dim3;
 pub use dim3::*;
 
+use super::Mesh;
+
 /// A trait for shapes that can be turned into a [`Mesh`](super::Mesh).
 pub trait Meshable {
     /// The output of [`Self::mesh`]. This can either be a [`Mesh`](super::Mesh)
-    /// or a builder used for creating a [`Mesh`](super::Mesh).
+    /// or a [`MeshBuilder`] used for creating a [`Mesh`](super::Mesh).
     type Output;
 
     /// Creates a [`Mesh`](super::Mesh) for a shape.
     fn mesh(&self) -> Self::Output;
 }
+
+/// A trait used to build [`Mesh`]es from a configuration
+pub trait MeshBuilder {
+    /// Builds a [`Mesh`] based on the configuration in `self`.
+    fn build(&self) -> Mesh;
+}
+
+impl<T: MeshBuilder> From<T> for Mesh {
+    fn from(builder: T) -> Self {
+        builder.build()
+    }
+}