OrthographicProjection scaling mode + camera bundle refactoring (#400)

* add normalized orthographic projection

* custom scale for ScaledOrthographicProjection

* allow choosing base axis for ScaledOrthographicProjection

* cargo fmt

* add general (scaled) orthographic camera bundle

FIXME: does the same "far" trick from Camera2DBundle make any sense here?

* fixes

* camera bundles: rename and new ortho constructors

* unify orthographic projections

* give PerspectiveCameraBundle constructors like those of OrthographicCameraBundle

* update examples with new camera bundle syntax

* rename CameraUiBundle to UiCameraBundle

* update examples

* ScalingMode::None

* remove extra blank lines

* sane default bounds for orthographic projection

* fix alien_cake_addict example

* reorder ScalingMode enum variants

* ios example fix

Author: inodentry

crates/bevy_render/src/camera/projection.rs

@@ -51,6 +51,20 @@ pub enum WindowOrigin {
     BottomLeft,
 }
 
+#[derive(Debug, Clone, Reflect, Serialize, Deserialize)]
+#[reflect_value(Serialize, Deserialize)]
+pub enum ScalingMode {
+    /// Manually specify left/right/top/bottom values.
+    /// Ignore window resizing; the image will stretch.
+    None,
+    /// Match the window size. 1 world unit = 1 pixel.
+    WindowSize,
+    /// Keep vertical axis constant; resize horizontal with aspect ratio.
+    FixedVertical,
+    /// Keep horizontal axis constant; resize vertical with aspect ratio.
+    FixedHorizontal,
+}
+
 #[derive(Debug, Clone, Reflect)]
 #[reflect(Component)]
 pub struct OrthographicProjection {
@@ -61,36 +75,67 @@ pub struct OrthographicProjection {
     pub near: f32,
     pub far: f32,
     pub window_origin: WindowOrigin,
+    pub scaling_mode: ScalingMode,
+    pub scale: f32,
 }
 
 impl CameraProjection for OrthographicProjection {
     fn get_projection_matrix(&self) -> Mat4 {
         Mat4::orthographic_rh(
-            self.left,
-            self.right,
-            self.bottom,
-            self.top,
+            self.left * self.scale,
+            self.right * self.scale,
+            self.bottom * self.scale,
+            self.top * self.scale,
             self.near,
             self.far,
         )
     }
 
     fn update(&mut self, width: f32, height: f32) {
-        match self.window_origin {
-            WindowOrigin::Center => {
+        match (&self.scaling_mode, &self.window_origin) {
+            (ScalingMode::WindowSize, WindowOrigin::Center) => {
                 let half_width = width / 2.0;
                 let half_height = height / 2.0;
                 self.left = -half_width;
                 self.right = half_width;
                 self.top = half_height;
                 self.bottom = -half_height;
             }
-            WindowOrigin::BottomLeft => {
+            (ScalingMode::WindowSize, WindowOrigin::BottomLeft) => {
                 self.left = 0.0;
                 self.right = width;
                 self.top = height;
                 self.bottom = 0.0;
             }
+            (ScalingMode::FixedVertical, WindowOrigin::Center) => {
+                let aspect_ratio = width / height;
+                self.left = -aspect_ratio;
+                self.right = aspect_ratio;
+                self.top = 1.0;
+                self.bottom = -1.0;
+            }
+            (ScalingMode::FixedVertical, WindowOrigin::BottomLeft) => {
+                let aspect_ratio = width / height;
+                self.left = 0.0;
+                self.right = aspect_ratio;
+                self.top = 1.0;
+                self.bottom = 0.0;
+            }
+            (ScalingMode::FixedHorizontal, WindowOrigin::Center) => {
+                let aspect_ratio = height / width;
+                self.left = -1.0;
+                self.right = 1.0;
+                self.top = aspect_ratio;
+                self.bottom = -aspect_ratio;
+            }
+            (ScalingMode::FixedHorizontal, WindowOrigin::BottomLeft) => {
+                let aspect_ratio = height / width;
+                self.left = 0.0;
+                self.right = 1.0;
+                self.top = aspect_ratio;
+                self.bottom = 0.0;
+            }
+            (ScalingMode::None, _) => {}
         }
     }
 
@@ -102,13 +147,15 @@ impl CameraProjection for OrthographicProjection {
 impl Default for OrthographicProjection {
     fn default() -> Self {
         OrthographicProjection {
-            left: 0.0,
-            right: 0.0,
-            bottom: 0.0,
-            top: 0.0,
+            left: -1.0,
+            right: 1.0,
+            bottom: -1.0,
+            top: 1.0,
             near: 0.0,
             far: 1000.0,
             window_origin: WindowOrigin::Center,
+            scaling_mode: ScalingMode::WindowSize,
+            scale: 1.0,
         }
     }
 }

crates/bevy_render/src/entity.rs

@@ -22,19 +22,40 @@ pub struct MeshBundle {
     pub global_transform: GlobalTransform,
 }
 
-/// A component bundle for "3d camera" entities
+/// Component bundle for camera entities with perspective projection
+///
+/// Use this for 3D rendering.
 #[derive(Bundle)]
-pub struct Camera3dBundle {
+pub struct PerspectiveCameraBundle {
     pub camera: Camera,
     pub perspective_projection: PerspectiveProjection,
     pub visible_entities: VisibleEntities,
     pub transform: Transform,
     pub global_transform: GlobalTransform,
 }
 
-impl Default for Camera3dBundle {
+impl PerspectiveCameraBundle {
+    pub fn new_3d() -> Self {
+        Default::default()
+    }
+
+    pub fn with_name(name: &str) -> Self {
+        PerspectiveCameraBundle {
+            camera: Camera {
+                name: Some(name.to_string()),
+                ..Default::default()
+            },
+            perspective_projection: Default::default(),
+            visible_entities: Default::default(),
+            transform: Default::default(),
+            global_transform: Default::default(),
+        }
+    }
+}
+
+impl Default for PerspectiveCameraBundle {
     fn default() -> Self {
-        Camera3dBundle {
+        PerspectiveCameraBundle {
             camera: Camera {
                 name: Some(base::camera::CAMERA_3D.to_string()),
                 ..Default::default()
@@ -47,22 +68,24 @@ impl Default for Camera3dBundle {
     }
 }
 
-/// A component bundle for "2d camera" entities
+/// Component bundle for camera entities with orthographic projection
+///
+/// Use this for 2D games, isometric games, CAD-like 3D views.
 #[derive(Bundle)]
-pub struct Camera2dBundle {
+pub struct OrthographicCameraBundle {
     pub camera: Camera,
     pub orthographic_projection: OrthographicProjection,
     pub visible_entities: VisibleEntities,
     pub transform: Transform,
     pub global_transform: GlobalTransform,
 }
 
-impl Default for Camera2dBundle {
-    fn default() -> Self {
+impl OrthographicCameraBundle {
+    pub fn new_2d() -> Self {
         // we want 0 to be "closest" and +far to be "farthest" in 2d, so we offset
         // the camera's translation by far and use a right handed coordinate system
         let far = 1000.0;
-        Camera2dBundle {
+        OrthographicCameraBundle {
             camera: Camera {
                 name: Some(base::camera::CAMERA_2D.to_string()),
                 ..Default::default()
@@ -76,4 +99,30 @@ impl Default for Camera2dBundle {
             global_transform: Default::default(),
         }
     }
+
+    pub fn new_3d() -> Self {
+        OrthographicCameraBundle {
+            camera: Camera {
+                name: Some(base::camera::CAMERA_3D.to_string()),
+                ..Default::default()
+            },
+            orthographic_projection: Default::default(),
+            visible_entities: Default::default(),
+            transform: Default::default(),
+            global_transform: Default::default(),
+        }
+    }
+
+    pub fn with_name(name: &str) -> Self {
+        OrthographicCameraBundle {
+            camera: Camera {
+                name: Some(name.to_string()),
+                ..Default::default()
+            },
+            orthographic_projection: Default::default(),
+            visible_entities: Default::default(),
+            transform: Default::default(),
+            global_transform: Default::default(),
+        }
+    }
 }

crates/bevy_ui/src/entity.rs

@@ -164,20 +164,20 @@ impl Default for ButtonBundle {
 }
 
 #[derive(Bundle, Debug)]
-pub struct CameraUiBundle {
+pub struct UiCameraBundle {
     pub camera: Camera,
     pub orthographic_projection: OrthographicProjection,
     pub visible_entities: VisibleEntities,
     pub transform: Transform,
     pub global_transform: GlobalTransform,
 }
 
-impl Default for CameraUiBundle {
+impl Default for UiCameraBundle {
     fn default() -> Self {
         // we want 0 to be "closest" and +far to be "farthest" in 2d, so we offset
         // the camera's translation by far and use a right handed coordinate system
         let far = 1000.0;
-        CameraUiBundle {
+        UiCameraBundle {
             camera: Camera {
                 name: Some(crate::camera::CAMERA_UI.to_string()),
                 ..Default::default()

examples/2d/contributors.rs

@@ -55,8 +55,8 @@ fn setup(
     let texture_handle = asset_server.load("branding/icon.png");
 
     commands
-        .spawn(Camera2dBundle::default())
-        .spawn(CameraUiBundle::default());
+        .spawn(OrthographicCameraBundle::new_2d())
+        .spawn(UiCameraBundle::default());
 
     let mut sel = ContributorSelection {
         order: vec![],

examples/2d/sprite.rs

@@ -14,7 +14,7 @@ fn setup(
 ) {
     let texture_handle = asset_server.load("branding/icon.png");
     commands
-        .spawn(Camera2dBundle::default())
+        .spawn(OrthographicCameraBundle::new_2d())
         .spawn(SpriteBundle {
             material: materials.add(texture_handle.into()),
             ..Default::default()

examples/2d/sprite_sheet.rs

@@ -31,7 +31,7 @@ fn setup(
     let texture_atlas = TextureAtlas::from_grid(texture_handle, Vec2::new(24.0, 24.0), 7, 1);
     let texture_atlas_handle = texture_atlases.add(texture_atlas);
     commands
-        .spawn(Camera2dBundle::default())
+        .spawn(OrthographicCameraBundle::new_2d())
         .spawn(SpriteSheetBundle {
             texture_atlas: texture_atlas_handle,
             transform: Transform::from_scale(Vec3::splat(6.0)),

examples/2d/text2d.rs

@@ -11,7 +11,7 @@ fn main() {
 fn setup(commands: &mut Commands, asset_server: Res<AssetServer>) {
     commands
         // 2d camera
-        .spawn(Camera2dBundle::default())
+        .spawn(OrthographicCameraBundle::new_2d())
         .spawn(Text2dBundle {
             text: Text::with_section(
                 "This text is in the 2D scene.",

examples/2d/texture_atlas.rs

@@ -64,7 +64,7 @@ fn setup(
 
     // set up a scene to display our texture atlas
     commands
-        .spawn(Camera2dBundle::default())
+        .spawn(OrthographicCameraBundle::new_2d())
         // draw a sprite from the atlas
         .spawn(SpriteSheetBundle {
             transform: Transform {

examples/3d/3d_scene.rs

@@ -35,7 +35,7 @@ fn setup(
             ..Default::default()
         })
         // camera
-        .spawn(Camera3dBundle {
+        .spawn(PerspectiveCameraBundle {
             transform: Transform::from_xyz(-2.0, 2.5, 5.0)
                 .looking_at(Vec3::default(), Vec3::unit_y()),
             ..Default::default()

examples/3d/load_gltf.rs

@@ -15,7 +15,7 @@ fn setup(commands: &mut Commands, asset_server: Res<AssetServer>) {
             transform: Transform::from_xyz(4.0, 5.0, 4.0),
             ..Default::default()
         })
-        .spawn(Camera3dBundle {
+        .spawn(PerspectiveCameraBundle {
             transform: Transform::from_xyz(0.7, 0.7, 1.0)
                 .looking_at(Vec3::new(0.0, 0.3, 0.0), Vec3::unit_y()),
             ..Default::default()