1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258
//! This example demonstrates how to create a custom mesh,
//! assign a custom UV mapping for a custom texture,
//! and how to change the UV mapping at run-time.
use bevy::prelude::*;
use bevy::render::{
mesh::{Indices, VertexAttributeValues},
render_asset::RenderAssetUsages,
render_resource::PrimitiveTopology,
};
// Define a "marker" component to mark the custom mesh. Marker components are often used in Bevy for
// filtering entities in queries with With, they're usually not queried directly since they don't contain information within them.
#[derive(Component)]
struct CustomUV;
fn main() {
App::new()
.add_plugins(DefaultPlugins)
.add_systems(Startup, setup)
.add_systems(Update, input_handler)
.run();
}
fn setup(
mut commands: Commands,
asset_server: Res<AssetServer>,
mut materials: ResMut<Assets<StandardMaterial>>,
mut meshes: ResMut<Assets<Mesh>>,
) {
// Import the custom texture.
let custom_texture_handle: Handle<Image> = asset_server.load("textures/array_texture.png");
// Create and save a handle to the mesh.
let cube_mesh_handle: Handle<Mesh> = meshes.add(create_cube_mesh());
// Render the mesh with the custom texture using a PbrBundle, add the marker.
commands.spawn((
PbrBundle {
mesh: cube_mesh_handle,
material: materials.add(StandardMaterial {
base_color_texture: Some(custom_texture_handle),
..default()
}),
..default()
},
CustomUV,
));
// Transform for the camera and lighting, looking at (0,0,0) (the position of the mesh).
let camera_and_light_transform =
Transform::from_xyz(1.8, 1.8, 1.8).looking_at(Vec3::ZERO, Vec3::Y);
// Camera in 3D space.
commands.spawn(Camera3dBundle {
transform: camera_and_light_transform,
..default()
});
// Light up the scene.
commands.spawn(PointLightBundle {
transform: camera_and_light_transform,
..default()
});
// Text to describe the controls.
commands.spawn(
TextBundle::from_section(
"Controls:\nSpace: Change UVs\nX/Y/Z: Rotate\nR: Reset orientation",
TextStyle {
font_size: 20.0,
..default()
},
)
.with_style(Style {
position_type: PositionType::Absolute,
top: Val::Px(12.0),
left: Val::Px(12.0),
..default()
}),
);
}
// System to receive input from the user,
// check out examples/input/ for more examples about user input.
fn input_handler(
keyboard_input: Res<ButtonInput<KeyCode>>,
mesh_query: Query<&Handle<Mesh>, With<CustomUV>>,
mut meshes: ResMut<Assets<Mesh>>,
mut query: Query<&mut Transform, With<CustomUV>>,
time: Res<Time>,
) {
if keyboard_input.just_pressed(KeyCode::Space) {
let mesh_handle = mesh_query.get_single().expect("Query not successful");
let mesh = meshes.get_mut(mesh_handle).unwrap();
toggle_texture(mesh);
}
if keyboard_input.pressed(KeyCode::KeyX) {
for mut transform in &mut query {
transform.rotate_x(time.delta_seconds() / 1.2);
}
}
if keyboard_input.pressed(KeyCode::KeyY) {
for mut transform in &mut query {
transform.rotate_y(time.delta_seconds() / 1.2);
}
}
if keyboard_input.pressed(KeyCode::KeyZ) {
for mut transform in &mut query {
transform.rotate_z(time.delta_seconds() / 1.2);
}
}
if keyboard_input.pressed(KeyCode::KeyR) {
for mut transform in &mut query {
transform.look_to(Vec3::NEG_Z, Vec3::Y);
}
}
}
#[rustfmt::skip]
fn create_cube_mesh() -> Mesh {
// Keep the mesh data accessible in future frames to be able to mutate it in toggle_texture.
Mesh::new(PrimitiveTopology::TriangleList, RenderAssetUsages::MAIN_WORLD | RenderAssetUsages::RENDER_WORLD)
.with_inserted_attribute(
Mesh::ATTRIBUTE_POSITION,
// Each array is an [x, y, z] coordinate in local space.
// Meshes always rotate around their local [0, 0, 0] when a rotation is applied to their Transform.
// By centering our mesh around the origin, rotating the mesh preserves its center of mass.
vec![
// top (facing towards +y)
[-0.5, 0.5, -0.5], // vertex with index 0
[0.5, 0.5, -0.5], // vertex with index 1
[0.5, 0.5, 0.5], // etc. until 23
[-0.5, 0.5, 0.5],
// bottom (-y)
[-0.5, -0.5, -0.5],
[0.5, -0.5, -0.5],
[0.5, -0.5, 0.5],
[-0.5, -0.5, 0.5],
// right (+x)
[0.5, -0.5, -0.5],
[0.5, -0.5, 0.5],
[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
[0.5, 0.5, -0.5],
// left (-x)
[-0.5, -0.5, -0.5],
[-0.5, -0.5, 0.5],
[-0.5, 0.5, 0.5],
[-0.5, 0.5, -0.5],
// back (+z)
[-0.5, -0.5, 0.5],
[-0.5, 0.5, 0.5],
[0.5, 0.5, 0.5],
[0.5, -0.5, 0.5],
// forward (-z)
[-0.5, -0.5, -0.5],
[-0.5, 0.5, -0.5],
[0.5, 0.5, -0.5],
[0.5, -0.5, -0.5],
],
)
// Set-up UV coordinates to point to the upper (V < 0.5), "dirt+grass" part of the texture.
// Take a look at the custom image (assets/textures/array_texture.png)
// so the UV coords will make more sense
// Note: (0.0, 0.0) = Top-Left in UV mapping, (1.0, 1.0) = Bottom-Right in UV mapping
.with_inserted_attribute(
Mesh::ATTRIBUTE_UV_0,
vec![
// Assigning the UV coords for the top side.
[0.0, 0.2], [0.0, 0.0], [1.0, 0.0], [1.0, 0.25],
// Assigning the UV coords for the bottom side.
[0.0, 0.45], [0.0, 0.25], [1.0, 0.25], [1.0, 0.45],
// Assigning the UV coords for the right side.
[1.0, 0.45], [0.0, 0.45], [0.0, 0.2], [1.0, 0.2],
// Assigning the UV coords for the left side.
[1.0, 0.45], [0.0, 0.45], [0.0, 0.2], [1.0, 0.2],
// Assigning the UV coords for the back side.
[0.0, 0.45], [0.0, 0.2], [1.0, 0.2], [1.0, 0.45],
// Assigning the UV coords for the forward side.
[0.0, 0.45], [0.0, 0.2], [1.0, 0.2], [1.0, 0.45],
],
)
// For meshes with flat shading, normals are orthogonal (pointing out) from the direction of
// the surface.
// Normals are required for correct lighting calculations.
// Each array represents a normalized vector, which length should be equal to 1.0.
.with_inserted_attribute(
Mesh::ATTRIBUTE_NORMAL,
vec![
// Normals for the top side (towards +y)
[0.0, 1.0, 0.0],
[0.0, 1.0, 0.0],
[0.0, 1.0, 0.0],
[0.0, 1.0, 0.0],
// Normals for the bottom side (towards -y)
[0.0, -1.0, 0.0],
[0.0, -1.0, 0.0],
[0.0, -1.0, 0.0],
[0.0, -1.0, 0.0],
// Normals for the right side (towards +x)
[1.0, 0.0, 0.0],
[1.0, 0.0, 0.0],
[1.0, 0.0, 0.0],
[1.0, 0.0, 0.0],
// Normals for the left side (towards -x)
[-1.0, 0.0, 0.0],
[-1.0, 0.0, 0.0],
[-1.0, 0.0, 0.0],
[-1.0, 0.0, 0.0],
// Normals for the back side (towards +z)
[0.0, 0.0, 1.0],
[0.0, 0.0, 1.0],
[0.0, 0.0, 1.0],
[0.0, 0.0, 1.0],
// Normals for the forward side (towards -z)
[0.0, 0.0, -1.0],
[0.0, 0.0, -1.0],
[0.0, 0.0, -1.0],
[0.0, 0.0, -1.0],
],
)
// Create the triangles out of the 24 vertices we created.
// To construct a square, we need 2 triangles, therefore 12 triangles in total.
// To construct a triangle, we need the indices of its 3 defined vertices, adding them one
// by one, in a counter-clockwise order (relative to the position of the viewer, the order
// should appear counter-clockwise from the front of the triangle, in this case from outside the cube).
// Read more about how to correctly build a mesh manually in the Bevy documentation of a Mesh,
// further examples and the implementation of the built-in shapes.
.with_inserted_indices(Indices::U32(vec![
0,3,1 , 1,3,2, // triangles making up the top (+y) facing side.
4,5,7 , 5,6,7, // bottom (-y)
8,11,9 , 9,11,10, // right (+x)
12,13,15 , 13,14,15, // left (-x)
16,19,17 , 17,19,18, // back (+z)
20,21,23 , 21,22,23, // forward (-z)
]))
}
// Function that changes the UV mapping of the mesh, to apply the other texture.
fn toggle_texture(mesh_to_change: &mut Mesh) {
// Get a mutable reference to the values of the UV attribute, so we can iterate over it.
let uv_attribute = mesh_to_change.attribute_mut(Mesh::ATTRIBUTE_UV_0).unwrap();
// The format of the UV coordinates should be Float32x2.
let VertexAttributeValues::Float32x2(uv_attribute) = uv_attribute else {
panic!("Unexpected vertex format, expected Float32x2.");
};
// Iterate over the UV coordinates, and change them as we want.
for uv_coord in uv_attribute.iter_mut() {
// If the UV coordinate points to the upper, "dirt+grass" part of the texture...
if (uv_coord[1] + 0.5) < 1.0 {
// ... point to the equivalent lower, "sand+water" part instead,
uv_coord[1] += 0.5;
} else {
// else, point back to the upper, "dirt+grass" part.
uv_coord[1] -= 0.5;
}
}
}