From 5eea01031944a8075856964f63aa367729aeedc5 Mon Sep 17 00:00:00 2001
From: devil-ira <justthecooldude@gmail.com>
Date: Fri, 13 Jan 2023 15:58:09 +0100
Subject: [PATCH] x

---
 Cargo.toml                          | 10 +++
 examples/3d/3d_viewport_to_world.rs | 95 +++++++++++++++++++++++++++++
 2 files changed, 105 insertions(+)
 create mode 100644 examples/3d/3d_viewport_to_world.rs

diff --git a/Cargo.toml b/Cargo.toml
index aa2eb4571a7fd1..1088c6c1b690f2 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -279,6 +279,16 @@ description = "Simple 3D scene with basic shapes and lighting"
 category = "3D Rendering"
 wasm = true
 
+[[example]]
+name = "3d_viewport_to_world"
+path = "examples/3d/3d_viewport_to_world.rs"
+
+[package.metadata.example.3d_viewport_to_world]
+name = "3D Viewport To World"
+description = "Use the cursor to move a cube through the scene"
+category = "3D Rendering"
+wasm = true
+
 [[example]]
 name = "3d_shapes"
 path = "examples/3d/3d_shapes.rs"
diff --git a/examples/3d/3d_viewport_to_world.rs b/examples/3d/3d_viewport_to_world.rs
new file mode 100644
index 00000000000000..350eed89455159
--- /dev/null
+++ b/examples/3d/3d_viewport_to_world.rs
@@ -0,0 +1,95 @@
+use bevy::prelude::*;
+
+fn main() {
+    App::new()
+        .add_plugins(DefaultPlugins)
+        .add_startup_system(setup)
+        .add_system(move_cube)
+        .run();
+}
+
+fn move_cube(
+    camera_query: Query<(&Camera, &GlobalTransform)>,
+    mut cube_query: Query<&mut Transform, With<Cube>>,
+    windows: Res<Windows>,
+    input: Res<Input<MouseButton>>,
+) {
+    let (camera, camera_transform) = camera_query.single();
+    let mut transform = cube_query.single_mut();
+
+    if !input.pressed(MouseButton::Left) {
+        return;
+    }
+
+    let Some(cursor_position) = windows.primary().cursor_position() else { return; };
+
+    let Some(ray) = camera.viewport_to_world(camera_transform, cursor_position) else { return; };
+
+    let Some(distance) = ray.intersect_plane(Vec3::ZERO, Vec3::Y) else { return; };
+
+    let point = ray.get_point(distance);
+    transform.translation = point + Vec3::Y * 0.5;
+}
+
+#[derive(Component)]
+struct Cube;
+
+fn setup(
+    mut commands: Commands,
+    mut meshes: ResMut<Assets<Mesh>>,
+    mut materials: ResMut<Assets<StandardMaterial>>,
+    asset_server: Res<AssetServer>,
+) {
+    // plane
+    commands.spawn(PbrBundle {
+        mesh: meshes.add(Mesh::from(shape::Plane { size: 50.0 })),
+        material: materials.add(Color::rgb(0.3, 0.5, 0.3).into()),
+        ..default()
+    });
+
+    // cube
+    commands
+        .spawn(PbrBundle {
+            mesh: meshes.add(Mesh::from(shape::Cube { size: 1.0 })),
+            material: materials.add(Color::rgb(0.8, 0.7, 0.6).into()),
+            transform: Transform::from_xyz(0.0, 0.5, 0.0),
+            ..default()
+        })
+        .insert(Cube);
+
+    // light
+    const HALF_SIZE: f32 = 15.0;
+    commands.spawn(DirectionalLightBundle {
+        transform: Transform::from_translation(Vec3::ONE).looking_at(Vec3::ZERO, Vec3::Y),
+        directional_light: DirectionalLight {
+            shadows_enabled: true,
+            shadow_projection: OrthographicProjection {
+                left: -HALF_SIZE,
+                right: HALF_SIZE,
+                bottom: -HALF_SIZE,
+                top: HALF_SIZE,
+                near: -10.0 * HALF_SIZE,
+                far: 10.0 * HALF_SIZE,
+                ..default()
+            },
+            ..default()
+        },
+        ..default()
+    });
+
+    // camera
+    commands.spawn(Camera3dBundle {
+        transform: Transform::from_xyz(0.0, 6.0, 6.0).looking_at(Vec3::ZERO, Vec3::Y),
+        ..default()
+    });
+
+    // UI
+    commands.spawn(TextBundle::from_section(
+        "Press the left mouse button to reposition the box.",
+        TextStyle {
+            font: asset_server.load("fonts/FiraMono-Medium.ttf"),
+            font_size: 32.,
+            ..default()
+        },
+    ));
+}