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Add example to demonstrate manual generation and UV mapping of 3D mesh (generate_custom_mesh) solve #4922 (#8909)
# Objective - Fixes #4922 ## Solution - Add an example that maps a custom texture on a 3D mesh. --- ## Changelog > Added the texture itself (confirmed with mod on discord before it should be ok) to the assets folder, added to the README and Cargo.toml. --------- Co-authored-by: Nicola Papale <nicopap@users.noreply.github.com> Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com> Co-authored-by: Sélène Amanita <134181069+Selene-Amanita@users.noreply.github.com>
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Adam Kobzan
GitHub
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3 changed files with 279 additions and 0 deletions
10
Cargo.toml
10
Cargo.toml
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@ -447,6 +447,16 @@ description = "A scene showcasing the built-in 3D shapes"
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category = "3D Rendering"
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wasm = true
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[[example]]
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name = "generate_custom_mesh"
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path = "examples/3d/generate_custom_mesh.rs"
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[package.metadata.example.generate_custom_mesh]
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name = "Generate Custom Mesh"
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description = "Simple showcase of how to generate a custom mesh with a custom texture"
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category = "3D Rendering"
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wasm = true
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[[example]]
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name = "anti_aliasing"
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path = "examples/3d/anti_aliasing.rs"
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268
examples/3d/generate_custom_mesh.rs
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268
examples/3d/generate_custom_mesh.rs
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@ -0,0 +1,268 @@
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// ! This example demonstrates how to create a custom mesh,
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// ! assign a custom UV mapping for a custom texture,
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// ! and how to change the UV mapping at run-time.
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use bevy::prelude::*;
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use bevy::render::mesh::Indices;
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use bevy::render::mesh::VertexAttributeValues;
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use bevy::render::render_resource::PrimitiveTopology;
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// Define a "marker" component to mark the custom mesh. Marker components are often used in Bevy for
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// filtering entities in queries with With, they're usually not queried directly since they don't contain information within them.
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#[derive(Component)]
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struct CustomUV;
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fn main() {
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App::new()
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.add_plugins(DefaultPlugins)
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.add_systems(Startup, setup)
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.add_systems(Update, input_handler)
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.run();
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}
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fn setup(
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mut commands: Commands,
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asset_server: ResMut<AssetServer>,
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mut materials: ResMut<Assets<StandardMaterial>>,
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mut meshes: ResMut<Assets<Mesh>>,
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) {
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// Import the custom texture.
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let custom_texture_handle: Handle<Image> = asset_server.load("textures/array_texture.png");
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// Create and save a handle to the mesh.
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let cube_mesh_handle: Handle<Mesh> = meshes.add(create_cube_mesh());
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// Render the mesh with the custom texture using a PbrBundle, add the marker.
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commands.spawn((
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PbrBundle {
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mesh: cube_mesh_handle,
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material: materials.add(StandardMaterial {
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base_color_texture: Some(custom_texture_handle),
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..default()
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}),
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..default()
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},
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CustomUV,
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));
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// Transform for the camera and lighting, looking at (0,0,0) (the position of the mesh).
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let camera_and_light_transform =
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Transform::from_xyz(1.8, 1.8, 1.8).looking_at(Vec3::ZERO, Vec3::Y);
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// Camera in 3D space.
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commands.spawn(Camera3dBundle {
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transform: camera_and_light_transform,
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..default()
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});
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// Light up the scene.
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commands.spawn(PointLightBundle {
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point_light: PointLight {
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intensity: 1000.0,
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range: 100.0,
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..default()
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},
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transform: camera_and_light_transform,
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..default()
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});
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// Text to describe the controls.
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commands.spawn(
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TextBundle::from_section(
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"Controls:\nSpace: Change UVs\nX/Y/Z: Rotate\nR: Reset orientation",
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TextStyle {
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font_size: 20.0,
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..default()
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},
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)
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.with_style(Style {
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position_type: PositionType::Absolute,
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top: Val::Px(12.0),
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left: Val::Px(12.0),
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..default()
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}),
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);
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}
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// System to receive input from the user,
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// check out examples/input/ for more examples about user input.
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fn input_handler(
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keyboard_input: Res<Input<KeyCode>>,
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mesh_query: Query<&Handle<Mesh>, With<CustomUV>>,
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mut meshes: ResMut<Assets<Mesh>>,
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mut query: Query<&mut Transform, With<CustomUV>>,
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time: Res<Time>,
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) {
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if keyboard_input.just_pressed(KeyCode::Space) {
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let mesh_handle = mesh_query.get_single().expect("Query not successful");
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let mesh = meshes.get_mut(mesh_handle).unwrap();
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toggle_texture(mesh);
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}
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if keyboard_input.pressed(KeyCode::X) {
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for mut transform in &mut query {
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transform.rotate_x(time.delta_seconds() / 1.2);
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}
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}
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if keyboard_input.pressed(KeyCode::Y) {
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for mut transform in &mut query {
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transform.rotate_y(time.delta_seconds() / 1.2);
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}
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}
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if keyboard_input.pressed(KeyCode::Z) {
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for mut transform in &mut query {
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transform.rotate_z(time.delta_seconds() / 1.2);
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}
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}
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if keyboard_input.pressed(KeyCode::R) {
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for mut transform in &mut query {
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transform.look_to(Vec3::NEG_Z, Vec3::Y);
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}
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}
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}
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fn create_cube_mesh() -> Mesh {
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let mut cube_mesh = Mesh::new(PrimitiveTopology::TriangleList);
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#[rustfmt::skip]
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cube_mesh.insert_attribute(
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Mesh::ATTRIBUTE_POSITION,
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// Each array is an [x, y, z] coordinate in local space.
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// Meshes always rotate around their local [0, 0, 0] when a rotation is applied to their Transform.
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// By centering our mesh around the origin, rotating the mesh preserves its center of mass.
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vec![
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// top (facing towards +y)
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[-0.5, 0.5, -0.5], // vertex with index 0
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[0.5, 0.5, -0.5], // vertex with index 1
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[0.5, 0.5, 0.5], // etc. until 23
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[-0.5, 0.5, 0.5],
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// bottom (-y)
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[-0.5, -0.5, -0.5],
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[0.5, -0.5, -0.5],
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[0.5, -0.5, 0.5],
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[-0.5, -0.5, 0.5],
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// right (+x)
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[0.5, -0.5, -0.5],
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[0.5, -0.5, 0.5],
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[0.5, 0.5, 0.5], // This vertex is at the same position as vertex with index 2, but they'll have different UV and normal
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[0.5, 0.5, -0.5],
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// left (-x)
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[-0.5, -0.5, -0.5],
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[-0.5, -0.5, 0.5],
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[-0.5, 0.5, 0.5],
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[-0.5, 0.5, -0.5],
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// back (+z)
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[-0.5, -0.5, 0.5],
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[-0.5, 0.5, 0.5],
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[0.5, 0.5, 0.5],
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[0.5, -0.5, 0.5],
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// forward (-z)
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[-0.5, -0.5, -0.5],
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[-0.5, 0.5, -0.5],
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[0.5, 0.5, -0.5],
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[0.5, -0.5, -0.5],
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],
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);
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// Set-up UV coordinated to point to the upper (V < 0.5), "dirt+grass" part of the texture.
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// Take a look at the custom image (assets/textures/array_texture.png)
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// so the UV coords will make more sense
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// Note: (0.0, 0.0) = Top-Left in UV mapping, (1.0, 1.0) = Bottom-Right in UV mapping
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#[rustfmt::skip]
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cube_mesh.insert_attribute(
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Mesh::ATTRIBUTE_UV_0,
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vec![
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// Assigning the UV coords for the top side.
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[0.0, 0.2], [0.0, 0.0], [1.0, 0.0], [1.0, 0.25],
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// Assigning the UV coords for the bottom side.
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[0.0, 0.45], [0.0, 0.25], [1.0, 0.25], [1.0, 0.45],
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// Assigning the UV coords for the right side.
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[1.0, 0.45], [0.0, 0.45], [0.0, 0.2], [1.0, 0.2],
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// Assigning the UV coords for the left side.
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[1.0, 0.45], [0.0, 0.45], [0.0, 0.2], [1.0, 0.2],
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// Assigning the UV coords for the back side.
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[0.0, 0.45], [0.0, 0.2], [1.0, 0.2], [1.0, 0.45],
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// Assigning the UV coords for the forward side.
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[0.0, 0.45], [0.0, 0.2], [1.0, 0.2], [1.0, 0.45],
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],
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);
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// For meshes with flat shading, normals are orthogonal (pointing out) from the direction of
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// the surface.
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// Normals are required for correct lighting calculations.
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// Each array represents a normalized vector, which length should be equal to 1.0.
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#[rustfmt::skip]
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cube_mesh.insert_attribute(
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Mesh::ATTRIBUTE_NORMAL,
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vec![
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// Normals for the top side (towards +y)
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[0.0, 1.0, 0.0],
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[0.0, 1.0, 0.0],
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[0.0, 1.0, 0.0],
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[0.0, 1.0, 0.0],
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// Normals for the bottom side (towards -y)
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[0.0, -1.0, 0.0],
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[0.0, -1.0, 0.0],
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[0.0, -1.0, 0.0],
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[0.0, -1.0, 0.0],
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// Normals for the right side (towards +x)
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[1.0, 0.0, 0.0],
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[1.0, 0.0, 0.0],
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[1.0, 0.0, 0.0],
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[1.0, 0.0, 0.0],
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// Normals for the left side (towards -x)
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[-1.0, 0.0, 0.0],
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[-1.0, 0.0, 0.0],
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[-1.0, 0.0, 0.0],
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[-1.0, 0.0, 0.0],
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// Normals for the back side (towards +z)
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[0.0, 0.0, 1.0],
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[0.0, 0.0, 1.0],
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[0.0, 0.0, 1.0],
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[0.0, 0.0, 1.0],
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// Normals for the forward side (towards -z)
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[0.0, 0.0, -1.0],
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[0.0, 0.0, -1.0],
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[0.0, 0.0, -1.0],
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[0.0, 0.0, -1.0],
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],
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);
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// Create the triangles out of the 24 vertices we created.
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// To construct a square, we need 2 triangles, therefore 12 triangles in total.
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// To construct a triangle, we need the indices of its 3 defined vertices, adding them one
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// by one, in a counter-clockwise order (relative to the position of the viewer, the order
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// should appear counter-clockwise from the front of the triangle, in this case from outside the cube).
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// Read more about how to correctly build a mesh manually in the Bevy documentation of a Mesh,
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// further examples and the implementation of the built-in shapes.
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#[rustfmt::skip]
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cube_mesh.set_indices(Some(Indices::U32(vec![
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0,3,1 , 1,3,2, // triangles making up the top (+y) facing side.
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4,5,7 , 5,6,7, // bottom (-y)
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8,11,9 , 9,11,10, // right (+x)
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12,13,15 , 13,14,15, // left (-x)
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16,19,17 , 17,19,18, // back (+z)
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20,21,23 , 21,22,23, // forward (-z)
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])));
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cube_mesh
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}
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// Function that changes the UV mapping of the mesh, to apply the other texture.
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fn toggle_texture(mesh_to_change: &mut Mesh) {
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// Get a mutable reference to the values of the UV attribute, so we can iterate over it.
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let uv_attribute = mesh_to_change.attribute_mut(Mesh::ATTRIBUTE_UV_0).unwrap();
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// The format of the UV coordinates should be Float32x2.
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let VertexAttributeValues::Float32x2(uv_attribute) = uv_attribute else {
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panic!("Unexpected vertex format, expected Float32x2.");
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};
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// Iterate over the UV coordinates, and change them as we want.
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for uv_coord in uv_attribute.iter_mut() {
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// If the UV coordinate points to the upper, "dirt+grass" part of the texture...
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if (uv_coord[1] + 0.5) < 1.0 {
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// ... point to the equivalent lower, "sand+water" part instead,
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uv_coord[1] += 0.5;
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} else {
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// else, point back to the upper, "dirt+grass" part.
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uv_coord[1] -= 0.5;
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}
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}
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}
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@ -120,6 +120,7 @@ Example | Description
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[Atmospheric Fog](../examples/3d/atmospheric_fog.rs) | A scene showcasing the atmospheric fog effect
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[Blend Modes](../examples/3d/blend_modes.rs) | Showcases different blend modes
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[Fog](../examples/3d/fog.rs) | A scene showcasing the distance fog effect
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[Generate Custom Mesh](../examples/3d/generate_custom_mesh.rs) | Simple showcase of how to generate a custom mesh with a custom texture
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[Lighting](../examples/3d/lighting.rs) | Illustrates various lighting options in a simple scene
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[Lines](../examples/3d/lines.rs) | Create a custom material to draw 3d lines
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[Load glTF](../examples/3d/load_gltf.rs) | Loads and renders a glTF file as a scene
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