custom_projection/
custom_projection.rs

1//! Demonstrates how to define and use custom camera projections.
2
3use bevy::prelude::*;
4use bevy::render::camera::CameraProjection;
5
6fn main() {
7    App::new()
8        .add_plugins(DefaultPlugins)
9        .add_systems(Startup, setup)
10        .run();
11}
12
13/// Like a perspective projection, but the vanishing point is not centered.
14#[derive(Debug, Clone)]
15struct ObliquePerspectiveProjection {
16    horizontal_obliqueness: f32,
17    vertical_obliqueness: f32,
18    perspective: PerspectiveProjection,
19}
20
21/// Implement the [`CameraProjection`] trait for our custom projection:
22impl CameraProjection for ObliquePerspectiveProjection {
23    fn get_clip_from_view(&self) -> Mat4 {
24        let mut mat = self.perspective.get_clip_from_view();
25        mat.col_mut(2)[0] = self.horizontal_obliqueness;
26        mat.col_mut(2)[1] = self.vertical_obliqueness;
27        mat
28    }
29
30    fn get_clip_from_view_for_sub(&self, sub_view: &bevy_render::camera::SubCameraView) -> Mat4 {
31        let mut mat = self.perspective.get_clip_from_view_for_sub(sub_view);
32        mat.col_mut(2)[0] = self.horizontal_obliqueness;
33        mat.col_mut(2)[1] = self.vertical_obliqueness;
34        mat
35    }
36
37    fn update(&mut self, width: f32, height: f32) {
38        self.perspective.update(width, height);
39    }
40
41    fn far(&self) -> f32 {
42        self.perspective.far
43    }
44
45    fn get_frustum_corners(&self, z_near: f32, z_far: f32) -> [Vec3A; 8] {
46        self.perspective.get_frustum_corners(z_near, z_far)
47    }
48}
49
50fn setup(
51    mut commands: Commands,
52    mut meshes: ResMut<Assets<Mesh>>,
53    mut materials: ResMut<Assets<StandardMaterial>>,
54) {
55    commands.spawn((
56        Camera3d::default(),
57        // Use our custom projection:
58        Projection::custom(ObliquePerspectiveProjection {
59            horizontal_obliqueness: 0.2,
60            vertical_obliqueness: 0.6,
61            perspective: PerspectiveProjection::default(),
62        }),
63        Transform::from_xyz(-2.5, 4.5, 9.0).looking_at(Vec3::ZERO, Vec3::Y),
64    ));
65
66    // Scene setup
67    commands.spawn((
68        Mesh3d(meshes.add(Circle::new(4.0))),
69        MeshMaterial3d(materials.add(Color::WHITE)),
70        Transform::from_rotation(Quat::from_rotation_x(-std::f32::consts::FRAC_PI_2)),
71    ));
72    commands.spawn((
73        Mesh3d(meshes.add(Cuboid::new(1.0, 1.0, 1.0))),
74        MeshMaterial3d(materials.add(Color::srgb_u8(124, 144, 255))),
75        Transform::from_xyz(0.0, 0.5, 0.0),
76    ));
77    commands.spawn((
78        PointLight {
79            shadows_enabled: true,
80            ..default()
81        },
82        Transform::from_xyz(4.0, 8.0, 4.0),
83    ));
84}
custom_projection/custom_projection.rs

custom_projection/
custom_projection.rs
