Change From<Icosphere> to TryFrom<Icosphere> (#6484)

# Objective

- Fixes  #6476

## Solution

- Return error instead of panic through `TryFrom`
- ~~Add `.except()` in examples~~ 
- Add `.unwrap()` in examples

crates/bevy_render/src/mesh/shape/icosphere.rs

@@ -1,5 +1,6 @@
 use crate::mesh::{Indices, Mesh};
 use hexasphere::shapes::IcoSphere;
+use thiserror::Error;
 use wgpu::PrimitiveTopology;
 
 /// A sphere made from a subdivided Icosahedron.
@@ -20,8 +21,19 @@ impl Default for Icosphere {
     }
 }
 
-impl From<Icosphere> for Mesh {
+#[derive(Debug, Clone, Error)]
-    fn from(sphere: Icosphere) -> Self {
+pub enum FromIcosphereError {
+    #[error("Cannot create an icosphere of {subdivisions} subdivisions due to there being too many vertices being generated: {number_of_resulting_points}. (Limited to 65535 vertices or 79 subdivisions)")]
+    TooManyVertices {
+        subdivisions: usize,
+        number_of_resulting_points: usize,
+    },
+}
+
+impl TryFrom<Icosphere> for Mesh {
+    type Error = FromIcosphereError;
+
+    fn try_from(sphere: Icosphere) -> Result<Self, Self::Error> {
         if sphere.subdivisions >= 80 {
             /*
             Number of triangles:
@@ -53,12 +65,10 @@ impl From<Icosphere> for Mesh {
             */
             let temp = sphere.subdivisions + 1;
             let number_of_resulting_points = temp * temp * 10 + 2;
-
+            return Err(FromIcosphereError::TooManyVertices {
-            panic!(
+                subdivisions: sphere.subdivisions,
-                "Cannot create an icosphere of {} subdivisions due to there being too many vertices being generated: {}. (Limited to 65535 vertices or 79 subdivisions)",
+                number_of_resulting_points,
-                sphere.subdivisions,
+            });
-                number_of_resulting_points
-            );
         }
         let generated = IcoSphere::new(sphere.subdivisions, |point| {
             let inclination = point.y.acos();
@@ -98,6 +108,6 @@ impl From<Icosphere> for Mesh {
         mesh.insert_attribute(Mesh::ATTRIBUTE_POSITION, points);
         mesh.insert_attribute(Mesh::ATTRIBUTE_NORMAL, normals);
         mesh.insert_attribute(Mesh::ATTRIBUTE_UV_0, uvs);
-        mesh
+        Ok(mesh)
     }
 }

examples/3d/3d_shapes.rs

@@ -38,7 +38,7 @@ fn setup(
         meshes.add(shape::Box::default().into()),
         meshes.add(shape::Capsule::default().into()),
         meshes.add(shape::Torus::default().into()),
-        meshes.add(shape::Icosphere::default().into()),
+        meshes.add(shape::Icosphere::default().try_into().unwrap()),
         meshes.add(shape::UVSphere::default().into()),
     ];
 

examples/3d/bloom.rs

@@ -47,7 +47,8 @@ fn setup_scene(
             radius: 0.5,
             subdivisions: 5,
         }
-        .into(),
+        .try_into()
+        .unwrap(),
     );
 
     for x in -10..10 {

examples/3d/pbr.rs

@@ -22,10 +22,13 @@ fn setup(
             let y01 = (y + 2) as f32 / 4.0;
             // sphere
             commands.spawn(PbrBundle {
-                mesh: meshes.add(Mesh::from(shape::Icosphere {
+                mesh: meshes.add(
-                    radius: 0.45,
+                    Mesh::try_from(shape::Icosphere {
-                    subdivisions: 32,
+                        radius: 0.45,
-                })),
+                        subdivisions: 32,
+                    })
+                    .unwrap(),
+                ),
                 material: materials.add(StandardMaterial {
                     base_color: Color::hex("ffd891").unwrap(),
                     // vary key PBR parameters on a grid of spheres to show the effect
@@ -40,10 +43,13 @@ fn setup(
     }
     // unlit sphere
     commands.spawn(PbrBundle {
-        mesh: meshes.add(Mesh::from(shape::Icosphere {
+        mesh: meshes.add(
-            radius: 0.45,
+            Mesh::try_from(shape::Icosphere {
-            subdivisions: 32,
+                radius: 0.45,
-        })),
+                subdivisions: 32,
+            })
+            .unwrap(),
+        ),
         material: materials.add(StandardMaterial {
             base_color: Color::hex("ffd891").unwrap(),
             // vary key PBR parameters on a grid of spheres to show the effect

examples/3d/shadow_biases.rs

@@ -42,10 +42,13 @@ fn setup(
         perceptual_roughness: 1.0,
         ..default()
     });
-    let sphere_handle = meshes.add(Mesh::from(shape::Icosphere {
+    let sphere_handle = meshes.add(
-        radius: sphere_radius,
+        Mesh::try_from(shape::Icosphere {
-        ..default()
+            radius: sphere_radius,
-    }));
+            ..default()
+        })
+        .unwrap(),
+    );
 
     println!("Using DirectionalLight");
 

examples/3d/shadow_caster_receiver.rs

@@ -37,10 +37,13 @@ fn setup(
         perceptual_roughness: 1.0,
         ..default()
     });
-    let sphere_handle = meshes.add(Mesh::from(shape::Icosphere {
+    let sphere_handle = meshes.add(
-        radius: sphere_radius,
+        Mesh::try_from(shape::Icosphere {
-        ..default()
+            radius: sphere_radius,
-    }));
+            ..default()
+        })
+        .unwrap(),
+    );
 
     // sphere - initially a caster
     commands.spawn(PbrBundle {

examples/3d/transparency_3d.rs

@@ -26,10 +26,13 @@ fn setup(
     });
     // transparent sphere, uses `alpha_mode: Mask(f32)`
     commands.spawn(PbrBundle {
-        mesh: meshes.add(Mesh::from(shape::Icosphere {
+        mesh: meshes.add(
-            radius: 0.5,
+            Mesh::try_from(shape::Icosphere {
-            subdivisions: 3,
+                radius: 0.5,
-        })),
+                subdivisions: 3,
+            })
+            .unwrap(),
+        ),
         material: materials.add(StandardMaterial {
             // Alpha channel of the color controls transparency.
             // We set it to 0.0 here, because it will be changed over time in the
@@ -46,10 +49,13 @@ fn setup(
     });
     // transparent unlit sphere, uses `alpha_mode: Mask(f32)`
     commands.spawn(PbrBundle {
-        mesh: meshes.add(Mesh::from(shape::Icosphere {
+        mesh: meshes.add(
-            radius: 0.5,
+            Mesh::try_from(shape::Icosphere {
-            subdivisions: 3,
+                radius: 0.5,
-        })),
+                subdivisions: 3,
+            })
+            .unwrap(),
+        ),
         material: materials.add(StandardMaterial {
             base_color: Color::rgba(0.2, 0.7, 0.1, 0.0),
             alpha_mode: AlphaMode::Mask(0.5),
@@ -71,10 +77,13 @@ fn setup(
     });
     // opaque sphere
     commands.spawn(PbrBundle {
-        mesh: meshes.add(Mesh::from(shape::Icosphere {
+        mesh: meshes.add(
-            radius: 0.5,
+            Mesh::try_from(shape::Icosphere {
-            subdivisions: 3,
+                radius: 0.5,
-        })),
+                subdivisions: 3,
+            })
+            .unwrap(),
+        ),
         material: materials.add(Color::rgb(0.7, 0.2, 0.1).into()),
         transform: Transform::from_xyz(0.0, 0.5, -1.5),
         ..default()

examples/animation/animated_transform.rs

@@ -118,7 +118,7 @@ fn setup(
     commands
         .spawn((
             PbrBundle {
-                mesh: meshes.add(Mesh::from(shape::Icosphere::default())),
+                mesh: meshes.add(Mesh::try_from(shape::Icosphere::default()).unwrap()),
                 material: materials.add(Color::rgb(0.8, 0.7, 0.6).into()),
                 ..default()
             },

examples/ecs/iter_combinations.rs

@@ -54,10 +54,13 @@ fn generate_bodies(
     mut meshes: ResMut<Assets<Mesh>>,
     mut materials: ResMut<Assets<StandardMaterial>>,
 ) {
-    let mesh = meshes.add(Mesh::from(shape::Icosphere {
+    let mesh = meshes.add(
-        radius: 1.0,
+        Mesh::try_from(shape::Icosphere {
-        subdivisions: 3,
+            radius: 1.0,
-    }));
+            subdivisions: 3,
+        })
+        .unwrap(),
+    );
 
     let color_range = 0.5..1.0;
     let vel_range = -0.5..0.5;
@@ -114,10 +117,13 @@ fn generate_bodies(
             BodyBundle {
                 pbr: PbrBundle {
                     transform: Transform::from_scale(Vec3::splat(star_radius)),
-                    mesh: meshes.add(Mesh::from(shape::Icosphere {
+                    mesh: meshes.add(
-                        radius: 1.0,
+                        Mesh::try_from(shape::Icosphere {
-                        subdivisions: 5,
+                            radius: 1.0,
-                    })),
+                            subdivisions: 5,
+                        })
+                        .unwrap(),
+                    ),
                     material: materials.add(StandardMaterial {
                         base_color: Color::ORANGE_RED,
                         emissive: (Color::ORANGE_RED * 2.),

examples/ios/src/lib.rs

@@ -67,10 +67,13 @@ fn setup_scene(
     });
     // sphere
     commands.spawn(PbrBundle {
-        mesh: meshes.add(Mesh::from(shape::Icosphere {
+        mesh: meshes.add(
-            subdivisions: 4,
+            Mesh::try_from(shape::Icosphere {
-            radius: 0.5,
+                subdivisions: 4,
-        })),
+                radius: 0.5,
+            })
+            .unwrap(),
+        ),
         material: materials.add(Color::rgb(0.1, 0.4, 0.8).into()),
         transform: Transform::from_xyz(1.5, 1.5, 1.5),
         ..default()

examples/stress_tests/many_lights.rs

@@ -47,10 +47,13 @@ fn setup(
     const N_LIGHTS: usize = 100_000;
 
     commands.spawn(PbrBundle {
-        mesh: meshes.add(Mesh::from(shape::Icosphere {
+        mesh: meshes.add(
-            radius: RADIUS,
+            Mesh::try_from(shape::Icosphere {
-            subdivisions: 9,
+                radius: RADIUS,
-        })),
+                subdivisions: 9,
+            })
+            .unwrap(),
+        ),
         material: materials.add(StandardMaterial::from(Color::WHITE)),
         transform: Transform::from_scale(Vec3::NEG_ONE),
         ..default()

examples/transforms/transform.rs

@@ -40,10 +40,13 @@ fn setup(
     // Add an object (sphere) for visualizing scaling.
     commands.spawn((
         PbrBundle {
-            mesh: meshes.add(Mesh::from(shape::Icosphere {
+            mesh: meshes.add(
-                radius: 3.0,
+                Mesh::try_from(shape::Icosphere {
-                subdivisions: 32,
+                    radius: 3.0,
-            })),
+                    subdivisions: 32,
+                })
+                .unwrap(),
+            ),
             material: materials.add(Color::YELLOW.into()),
             transform: Transform::from_translation(Vec3::ZERO),
             ..default()