Bevy 0.13 `3d_shapes.rs` but with normal debugging gizmos and wireframes

debug_normals.rs

//! This example demonstrates the built-in 3d shapes in Bevy.
//! The scene includes a patterned texture and a rotation for visualizing the normals and UVs.

use std::f32::consts::PI;

use bevy::{
    input::common_conditions::input_just_pressed,
    pbr::wireframe::{Wireframe, WireframePlugin},
    prelude::*,
    render::{
        mesh::VertexAttributeValues,
        render_asset::RenderAssetUsages,
        render_resource::{Extent3d, TextureDimension, TextureFormat},
    },
};

fn main() {
    App::new()
        .add_plugins((
            DefaultPlugins.set(ImagePlugin::default_nearest()),
            WireframePlugin,
        ))
        .init_resource::<Debug>()
        .add_systems(Startup, setup)
        .add_systems(
            Update,
            (
                rotate,
                debug_normals.run_if(resource_equals::<Debug>(Debug(true))),
                toggle_debug.run_if(input_just_pressed(KeyCode::Space)),
            ),
        )
        .run();
}

/// A marker component for our shapes so we can query them separately from the ground plane
#[derive(Component)]
struct Shape;

#[derive(Resource, Deref, DerefMut, Default, PartialEq)]
struct Debug(bool);

const X_EXTENT: f32 = 12.0;
const NORMAL_SCALE: f32 = 0.1;

fn setup(
    mut commands: Commands,
    mut meshes: ResMut<Assets<Mesh>>,
    mut images: ResMut<Assets<Image>>,
    mut materials: ResMut<Assets<StandardMaterial>>,
) {
    let debug_material = materials.add(StandardMaterial {
        base_color_texture: Some(images.add(uv_debug_texture())),
        ..default()
    });

    let shapes = [
        meshes.add(Cuboid::default()),
        meshes.add(Capsule3d::default()),
        meshes.add(Torus::default()),
        meshes.add(Cylinder::default()),
        meshes.add(Sphere::default().mesh().ico(5).unwrap()),
        meshes.add(Sphere::default().mesh().uv(32, 18)),
    ];

    let num_shapes = shapes.len();

    for (i, shape) in shapes.into_iter().enumerate() {
        commands.spawn((
            PbrBundle {
                mesh: shape,
                material: debug_material.clone(),
                transform: Transform::from_xyz(
                    -X_EXTENT / 2. + i as f32 / (num_shapes - 1) as f32 * X_EXTENT,
                    2.0,
                    0.0,
                )
                .with_rotation(Quat::from_rotation_x(-PI / 4.)),
                ..default()
            },
            Shape,
        ));
    }

    commands.spawn(PointLightBundle {
        point_light: PointLight {
            intensity: 1500000.0,
            range: 100.,
            shadows_enabled: true,
            ..default()
        },
        transform: Transform::from_xyz(8.0, 16.0, 8.0),
        ..default()
    });

    // ground plane
    commands.spawn(PbrBundle {
        mesh: meshes.add(Plane3d::default().mesh().size(50.0, 50.0)),
        material: materials.add(Color::SILVER),
        ..default()
    });

    commands.spawn(Camera3dBundle {
        transform: Transform::from_xyz(0.0, 6., 12.0).looking_at(Vec3::new(0., 1., 0.), Vec3::Y),
        ..default()
    });
}

fn rotate(mut query: Query<&mut Transform, With<Shape>>, time: Res<Time>) {
    for mut transform in &mut query {
        transform.rotate_y(time.delta_seconds() / 2.);
    }
}

/// Creates a colorful test pattern
fn uv_debug_texture() -> Image {
    const TEXTURE_SIZE: usize = 8;

    let mut palette: [u8; 32] = [
        255, 102, 159, 255, 255, 159, 102, 255, 236, 255, 102, 255, 121, 255, 102, 255, 102, 255,
        198, 255, 102, 198, 255, 255, 121, 102, 255, 255, 236, 102, 255, 255,
    ];

    let mut texture_data = [0; TEXTURE_SIZE * TEXTURE_SIZE * 4];
    for y in 0..TEXTURE_SIZE {
        let offset = TEXTURE_SIZE * y * 4;
        texture_data[offset..(offset + TEXTURE_SIZE * 4)].copy_from_slice(&palette);
        palette.rotate_right(4);
    }

    Image::new_fill(
        Extent3d {
            width: TEXTURE_SIZE as u32,
            height: TEXTURE_SIZE as u32,
            depth_or_array_layers: 1,
        },
        TextureDimension::D2,
        &texture_data,
        TextureFormat::Rgba8UnormSrgb,
        RenderAssetUsages::RENDER_WORLD,
    )
}

fn toggle_debug(
    mut commands: Commands,
    mut debug: ResMut<Debug>,
    shapes: Query<Entity, With<Shape>>,
) {
    **debug = !**debug;
    if **debug {
        for entity in &shapes {
            commands.entity(entity).insert(Wireframe);
        }
    } else {
        for entity in &shapes {
            commands.entity(entity).remove::<Wireframe>();
        }
    }
}

fn debug_normals(
    handles: Query<(&GlobalTransform, &Handle<Mesh>), With<Shape>>,
    meshes: Res<Assets<Mesh>>,
    mut gizmos: Gizmos,
) {
    for (transform, handle) in &handles {
        let Some(mesh) = meshes.get(handle) else {
            continue;
        };

        let Some(VertexAttributeValues::Float32x3(position_vals)) =
            mesh.attribute(Mesh::ATTRIBUTE_POSITION)
        else {
            continue;
        };

        let Some(VertexAttributeValues::Float32x3(normal_vals)) =
            mesh.attribute(Mesh::ATTRIBUTE_NORMAL)
        else {
            continue;
        };

        for (position, normal) in position_vals.iter().zip(normal_vals.iter()) {
            let (_, rotation, _) = transform.to_scale_rotation_translation();

            let position = transform.transform_point(Vec3::from(*position));
            let normal = Vec3::from(*normal);
            let color = if normal.is_normalized() {
                Color::WHITE
            } else {
                Color::TOMATO
            };
            let normal = (rotation * normal * NORMAL_SCALE) + position;

            gizmos.arrow(position, normal, color);
        }
    }
}