Use u16 indices if possible in mesh primitives

crates/bevy_math/Cargo.toml

@@ -74,6 +74,7 @@ mint = ["glam/mint"]
 libm = ["dep:libm", "glam/libm"]
 # Enable assertions to check the validity of parameters passed to glam
 glam_assert = ["glam/glam-assert"]
+glam_bytemuck = ["glam/bytemuck"]
 # Enable assertions in debug builds to check the validity of parameters passed to glam
 debug_glam_assert = ["glam/debug-glam-assert"]
 # Enable the rand dependency for shape_sampling

crates/bevy_mesh/Cargo.toml

@@ -13,7 +13,9 @@ keywords = ["bevy"]
 bevy_app = { path = "../bevy_app", version = "0.18.0-dev" }
 bevy_asset = { path = "../bevy_asset", version = "0.18.0-dev" }
 bevy_image = { path = "../bevy_image", version = "0.18.0-dev", optional = true }
-bevy_math = { path = "../bevy_math", version = "0.18.0-dev" }
+bevy_math = { path = "../bevy_math", version = "0.18.0-dev", features = [
+  "glam_bytemuck",
+] }
 bevy_reflect = { path = "../bevy_reflect", version = "0.18.0-dev" }
 bevy_ecs = { path = "../bevy_ecs", version = "0.18.0-dev" }
 bevy_transform = { path = "../bevy_transform", version = "0.18.0-dev" }

crates/bevy_mesh/src/index.rs

@@ -80,6 +80,15 @@ pub enum Indices {
 }
 
 impl Indices {
+    /// Create a empty indices with the given capacity and vertex count. It will be [`Indices::U16`] if the vertex count <= 65536, otherwise it will be [`Indices::U32`].
+    pub fn with_capacity(capacity: usize, vertex_count: u32) -> Self {
+        if vertex_count <= u16::MAX as u32 + 1 {
+            Indices::U16(Vec::with_capacity(capacity))
+        } else {
+            Indices::U32(Vec::with_capacity(capacity))
+        }
+    }
+
     /// Returns an iterator over the indices.
     pub fn iter(&self) -> impl Iterator<Item = usize> + '_ {
         match self {
@@ -109,6 +118,30 @@ impl Indices {
     pub fn push(&mut self, index: u32) {
         self.extend([index]);
     }
+
+    /// Resize the indices in place so that `len` is equal to `new_len`.
+    pub fn resize(&mut self, new_len: usize, value: u32) {
+        match self {
+            Indices::U16(indices) => {
+                indices.resize(new_len, value as u16);
+            }
+            Indices::U32(indices) => {
+                indices.resize(new_len, value);
+            }
+        }
+    }
+
+    /// Set a value of indices at the given index.
+    pub fn set(&mut self, index: usize, value: u32) {
+        match self {
+            Indices::U16(indices) => {
+                indices[index] = value as u16;
+            }
+            Indices::U32(indices) => {
+                indices[index] = value;
+            }
+        }
+    }
 }
 
 /// Extend the indices with indices from an iterator.

crates/bevy_mesh/src/primitives/dim2.rs

@@ -177,7 +177,7 @@ impl CircularSectorMeshBuilder {
 impl MeshBuilder for CircularSectorMeshBuilder {
     fn build(&self) -> Mesh {
         let resolution = self.resolution as usize;
-        let mut indices = Vec::with_capacity((resolution - 1) * 3);
+        let mut indices = Indices::with_capacity((resolution - 1) * 3, (resolution + 1) as u32);
         let mut positions = Vec::with_capacity(resolution + 1);
         let normals = vec![[0.0, 0.0, 1.0]; resolution + 1];
         let mut uvs = Vec::with_capacity(resolution + 1);
@@ -207,7 +207,7 @@ impl MeshBuilder for CircularSectorMeshBuilder {
 
         for i in 1..self.resolution {
             // Index 0 is the center.
-            indices.extend_from_slice(&[0, i, i + 1]);
+            indices.extend([0, i, i + 1]);
         }
 
         Mesh::new(
@@ -217,7 +217,7 @@ impl MeshBuilder for CircularSectorMeshBuilder {
         .with_inserted_attribute(Mesh::ATTRIBUTE_POSITION, positions)
         .with_inserted_attribute(Mesh::ATTRIBUTE_NORMAL, normals)
         .with_inserted_attribute(Mesh::ATTRIBUTE_UV_0, uvs)
-        .with_inserted_indices(Indices::U32(indices))
+        .with_inserted_indices(indices)
     }
 }
 
@@ -315,7 +315,7 @@ impl CircularSegmentMeshBuilder {
 impl MeshBuilder for CircularSegmentMeshBuilder {
     fn build(&self) -> Mesh {
         let resolution = self.resolution as usize;
-        let mut indices = Vec::with_capacity((resolution - 1) * 3);
+        let mut indices = Indices::with_capacity((resolution - 1) * 3, (resolution + 1) as u32);
         let mut positions = Vec::with_capacity(resolution + 1);
         let normals = vec![[0.0, 0.0, 1.0]; resolution + 1];
         let mut uvs = Vec::with_capacity(resolution + 1);
@@ -354,7 +354,7 @@ impl MeshBuilder for CircularSegmentMeshBuilder {
 
         for i in 1..self.resolution {
             // Index 0 is the midpoint of the chord.
-            indices.extend_from_slice(&[0, i, i + 1]);
+            indices.extend([0, i, i + 1]);
         }
 
         Mesh::new(
@@ -364,7 +364,7 @@ impl MeshBuilder for CircularSegmentMeshBuilder {
         .with_inserted_attribute(Mesh::ATTRIBUTE_POSITION, positions)
         .with_inserted_attribute(Mesh::ATTRIBUTE_NORMAL, normals)
         .with_inserted_attribute(Mesh::ATTRIBUTE_UV_0, uvs)
-        .with_inserted_indices(Indices::U32(indices))
+        .with_inserted_indices(indices)
     }
 }
 
@@ -429,21 +429,21 @@ impl Meshable for ConvexPolygon {
 impl MeshBuilder for ConvexPolygonMeshBuilder {
     fn build(&self) -> Mesh {
         let len = self.vertices.len();
-        let mut indices = Vec::with_capacity((len - 2) * 3);
+        let mut indices = Indices::with_capacity((len - 2) * 3, len as u32);
         let mut positions = Vec::with_capacity(len);
 
         for vertex in &self.vertices {
             positions.push([vertex.x, vertex.y, 0.0]);
         }
         for i in 2..len as u32 {
-            indices.extend_from_slice(&[0, i - 1, i]);
+            indices.extend([0, i - 1, i]);
         }
         Mesh::new(
             PrimitiveTopology::TriangleList,
             RenderAssetUsages::default(),
         )
         .with_inserted_attribute(Mesh::ATTRIBUTE_POSITION, positions)
-        .with_inserted_indices(Indices::U32(indices))
+        .with_inserted_indices(indices)
     }
 }
 
@@ -578,7 +578,7 @@ impl EllipseMeshBuilder {
 impl MeshBuilder for EllipseMeshBuilder {
     fn build(&self) -> Mesh {
         let resolution = self.resolution as usize;
-        let mut indices = Vec::with_capacity((resolution - 2) * 3);
+        let mut indices = Indices::with_capacity((resolution - 2) * 3, resolution as u32);
         let mut positions = Vec::with_capacity(resolution);
         let normals = vec![[0.0, 0.0, 1.0]; resolution];
         let mut uvs = Vec::with_capacity(resolution);
@@ -599,7 +599,7 @@ impl MeshBuilder for EllipseMeshBuilder {
         }
 
         for i in 1..(self.resolution - 1) {
-            indices.extend_from_slice(&[0, i, i + 1]);
+            indices.extend([0, i, i + 1]);
         }
 
         Mesh::new(
@@ -609,7 +609,7 @@ impl MeshBuilder for EllipseMeshBuilder {
         .with_inserted_attribute(Mesh::ATTRIBUTE_POSITION, positions)
         .with_inserted_attribute(Mesh::ATTRIBUTE_NORMAL, normals)
         .with_inserted_attribute(Mesh::ATTRIBUTE_UV_0, uvs)
-        .with_inserted_indices(Indices::U32(indices))
+        .with_inserted_indices(indices)
     }
 }
 
@@ -657,7 +657,7 @@ impl Segment2dMeshBuilder {
 impl MeshBuilder for Segment2dMeshBuilder {
     fn build(&self) -> Mesh {
         let positions = self.segment.vertices.map(|v| v.extend(0.0)).to_vec();
-        let indices = Indices::U32(vec![0, 1]);
+        let indices = Indices::U16(vec![0, 1]);
 
         Mesh::new(PrimitiveTopology::LineList, RenderAssetUsages::default())
             .with_inserted_attribute(Mesh::ATTRIBUTE_POSITION, positions)
@@ -696,11 +696,9 @@ impl MeshBuilder for Polyline2dMeshBuilder {
             .map(|v| v.extend(0.0))
             .collect();
 
-        let indices = Indices::U32(
-            (0..self.polyline.vertices.len() as u32 - 1)
-                .flat_map(|i| [i, i + 1])
-                .collect(),
-        );
+        let mut indices =
+            Indices::with_capacity(self.polyline.vertices.len() - 1, positions.len() as u32);
+        indices.extend((0..self.polyline.vertices.len() as u32 - 1).flat_map(|i| [i, i + 1]));
 
         Mesh::new(PrimitiveTopology::LineList, RenderAssetUsages::default())
             .with_inserted_indices(indices)
@@ -769,7 +767,7 @@ impl MeshBuilder for AnnulusMeshBuilder {
         let outer_radius = self.annulus.outer_circle.radius;
 
         let num_vertices = (self.resolution as usize + 1) * 2;
-        let mut indices = Vec::with_capacity(self.resolution as usize * 6);
+        let mut indices = Indices::with_capacity(self.resolution as usize * 6, num_vertices as u32);
         let mut positions = Vec::with_capacity(num_vertices);
         let mut uvs = Vec::with_capacity(num_vertices);
         let normals = vec![[0.0, 0.0, 1.0]; num_vertices];
@@ -807,8 +805,8 @@ impl MeshBuilder for AnnulusMeshBuilder {
             let outer_vertex = 2 * i + 1;
             let next_inner = inner_vertex + 2;
             let next_outer = outer_vertex + 2;
-            indices.extend_from_slice(&[inner_vertex, outer_vertex, next_outer]);
-            indices.extend_from_slice(&[next_outer, next_inner, inner_vertex]);
+            indices.extend([inner_vertex, outer_vertex, next_outer]);
+            indices.extend([next_outer, next_inner, inner_vertex]);
         }
 
         Mesh::new(
@@ -818,7 +816,7 @@ impl MeshBuilder for AnnulusMeshBuilder {
         .with_inserted_attribute(Mesh::ATTRIBUTE_POSITION, positions)
         .with_inserted_attribute(Mesh::ATTRIBUTE_NORMAL, normals)
         .with_inserted_attribute(Mesh::ATTRIBUTE_UV_0, uvs)
-        .with_inserted_indices(Indices::U32(indices))
+        .with_inserted_indices(indices)
     }
 }
 
@@ -906,7 +904,7 @@ impl MeshBuilder for RhombusMeshBuilder {
         ];
         let normals = vec![[0.0, 0.0, 1.0]; 4];
         let uvs = vec![[1.0, 0.5], [0.5, 0.0], [0.0, 0.5], [0.5, 1.0]];
-        let indices = Indices::U32(vec![0, 1, 2, 2, 3, 0]);
+        let indices = Indices::U16(vec![0, 1, 2, 2, 3, 0]);
 
         Mesh::new(
             PrimitiveTopology::TriangleList,
@@ -983,9 +981,9 @@ impl MeshBuilder for Triangle2dMeshBuilder {
 
         let is_ccw = self.triangle.winding_order() == WindingOrder::CounterClockwise;
         let indices = if is_ccw {
-            Indices::U32(vec![0, 1, 2])
+            Indices::U16(vec![0, 1, 2])
         } else {
-            Indices::U32(vec![2, 1, 0])
+            Indices::U16(vec![2, 1, 0])
         };
 
         Mesh::new(
@@ -1063,7 +1061,7 @@ impl MeshBuilder for RectangleMeshBuilder {
         ];
         let normals = vec![[0.0, 0.0, 1.0]; 4];
         let uvs = vec![[1.0, 0.0], [0.0, 0.0], [0.0, 1.0], [1.0, 1.0]];
-        let indices = Indices::U32(vec![0, 1, 2, 0, 2, 3]);
+        let indices = Indices::U16(vec![0, 1, 2, 0, 2, 3]);
 
         Mesh::new(
             PrimitiveTopology::TriangleList,
@@ -1149,7 +1147,8 @@ impl MeshBuilder for Capsule2dMeshBuilder {
         let vertex_count = 2 * resolution;
 
         // Six extra indices for the two triangles between the semicircles
-        let mut indices = Vec::with_capacity((resolution as usize - 2) * 2 * 3 + 6);
+        let mut indices =
+            Indices::with_capacity((resolution as usize - 2) * 2 * 3 + 6, vertex_count);
         let mut positions = Vec::with_capacity(vertex_count as usize);
         let normals = vec![[0.0, 0.0, 1.0]; vertex_count as usize];
         let mut uvs = Vec::with_capacity(vertex_count as usize);
@@ -1182,11 +1181,11 @@ impl MeshBuilder for Capsule2dMeshBuilder {
 
         // Add top semicircle indices
         for i in 1..resolution - 1 {
-            indices.extend_from_slice(&[0, i, i + 1]);
+            indices.extend([0, i, i + 1]);
         }
 
         // Add indices for top left triangle of the part between the semicircles
-        indices.extend_from_slice(&[0, resolution - 1, resolution]);
+        indices.extend([0, resolution - 1, resolution]);
 
         // Create bottom semicircle
         for i in resolution..vertex_count {
@@ -1201,11 +1200,11 @@ impl MeshBuilder for Capsule2dMeshBuilder {
 
         // Add bottom semicircle indices
         for i in 1..resolution - 1 {
-            indices.extend_from_slice(&[resolution, resolution + i, resolution + i + 1]);
+            indices.extend([resolution, resolution + i, resolution + i + 1]);
         }
 
         // Add indices for bottom right triangle of the part between the semicircles
-        indices.extend_from_slice(&[resolution, vertex_count - 1, 0]);
+        indices.extend([resolution, vertex_count - 1, 0]);
 
         Mesh::new(
             PrimitiveTopology::TriangleList,
@@ -1214,7 +1213,7 @@ impl MeshBuilder for Capsule2dMeshBuilder {
         .with_inserted_attribute(Mesh::ATTRIBUTE_POSITION, positions)
         .with_inserted_attribute(Mesh::ATTRIBUTE_NORMAL, normals)
         .with_inserted_attribute(Mesh::ATTRIBUTE_UV_0, uvs)
-        .with_inserted_indices(Indices::U32(indices))
+        .with_inserted_indices(indices)
     }
 }