Add test for mesh transformations

Cargo.toml

@@ -4165,6 +4165,15 @@ description = "Demonstrates specular tints and maps"
 category = "3D Rendering"
 wasm = true
 
+[[example]]
+name = "test_transform_mesh"
+path = "tests/3d/test_transform_mesh.rs"
+doc-scrape-examples = true
+required-features = ["pbr_anisotropy_texture"]
+
+[package.metadata.example.test_transform_mesh]
+hidden = true
+
 [profile.wasm-release]
 inherits = "release"
 opt-level = "z"

tests/3d/test_transform_mesh.rs

@@ -0,0 +1,118 @@
+//! Test that transforming a mesh correctly updates normals and tangents.
+
+use bevy::prelude::*;
+use bevy::render::camera::ScalingMode;
+
+fn main() {
+    App::new()
+        .add_plugins(DefaultPlugins)
+        .add_systems(Startup, (setup_environment, setup_meshes))
+        .add_systems(Update, animate_light)
+        .run();
+}
+
+fn setup_environment(
+    mut commands: Commands,
+    mut mesh_assets: ResMut<Assets<Mesh>>,
+    mut material_assets: ResMut<Assets<StandardMaterial>>,
+) {
+    let description = "(left to right)\n\
+        0: Original mesh.\n\
+        1: Transformed via mesh attributes.\n\
+        2: Transformed via mesh attributes, normals and tangents recalculated.\n\
+        3: Transformed via entity.";
+
+    commands.spawn((
+        Text::new(description),
+        Node {
+            position_type: PositionType::Absolute,
+            top: Val::Px(12.0),
+            left: Val::Px(12.0),
+            ..default()
+        },
+    ));
+
+    commands.spawn((
+        Camera3d::default(),
+        Transform::from_xyz(0.0, 0.0, 1.0).looking_at(Vec3::new(0.0, 0.0, 0.0), Vec3::Y),
+        Projection::Orthographic(OrthographicProjection {
+            scaling_mode: ScalingMode::AutoMin {
+                min_width: 13.0,
+                min_height: 5.0,
+            },
+            ..OrthographicProjection::default_3d()
+        }),
+    ));
+
+    commands.spawn((
+        Transform::from_xyz(1.0, 1.0, 0.5).looking_at(Vec3::ZERO, Vec3::Y),
+        DirectionalLight {
+            shadows_enabled: true,
+            ..default()
+        },
+    ));
+
+    commands.spawn((
+        Transform::from_xyz(0.0, 0.0, -11.0),
+        Mesh3d(mesh_assets.add(Plane3d::default().mesh().size(100.0, 100.0).normal(Dir3::Z))),
+        MeshMaterial3d(material_assets.add(StandardMaterial {
+            base_color: Color::srgb(0.05, 0.05, 0.15),
+            reflectance: 0.2,
+            ..default()
+        })),
+    ));
+}
+
+fn setup_meshes(
+    mut commands: Commands,
+    mut mesh_assets: ResMut<Assets<Mesh>>,
+    mut material_assets: ResMut<Assets<StandardMaterial>>,
+) {
+    let material = MeshMaterial3d(material_assets.add(StandardMaterial {
+        base_color: Color::srgb(0.2, 0.4, 0.2),
+        // Add anisotropy so that lighting is dependent on tangents.
+        anisotropy_rotation: 0.5,
+        anisotropy_strength: 1.0,
+        ..Default::default()
+    }));
+
+    let transform = Transform::from_scale(Vec3::new(1.5, 0.5, 1.0)).with_rotation(
+        Quat::from_axis_angle(Vec3::splat(1.0).normalize(), 135.0_f32.to_radians()),
+    );
+
+    let original_mesh = Mesh::from(Sphere::new(1.0))
+        .with_computed_normals()
+        .with_generated_tangents()
+        .unwrap();
+
+    let transformed_mesh = original_mesh.clone().transformed_by(transform);
+
+    let recalculated_mesh = transformed_mesh
+        .clone()
+        .with_computed_normals()
+        .with_generated_tangents()
+        .unwrap();
+
+    let original_mesh = mesh_assets.add(original_mesh);
+    let transformed_mesh = mesh_assets.add(transformed_mesh);
+    let recalculated_mesh = mesh_assets.add(recalculated_mesh);
+
+    for (mesh_handle, transform) in [
+        (&original_mesh, Transform::from_xyz(-4.5, 0.0, -10.0)),
+        (&transformed_mesh, Transform::from_xyz(-1.5, 0.0, -10.0)),
+        (&recalculated_mesh, Transform::from_xyz(1.5, 0.0, -10.0)),
+        (
+            &original_mesh,
+            Transform::from_xyz(4.5, 0.0, -10.0) * transform,
+        ),
+    ] {
+        commands.spawn((Mesh3d(mesh_handle.clone()), transform, material.clone()));
+    }
+}
+
+fn animate_light(mut lights: Query<&mut Transform, With<DirectionalLight>>, time: Res<Time>) {
+    for mut transform in lights.iter_mut() {
+        transform.translation = vec3(ops::cos(time.elapsed_secs()), 1.0, 1.0);
+        transform.look_at(Vec3::ZERO, Vec3::Y);
+    }
+}