Make SubCameraView into a new primitive shape

Cargo.toml

@@ -3952,13 +3952,13 @@ category = "3D Rendering"
 wasm = false
 
 [[example]]
-name = "camera_sub_view"
-path = "examples/3d/camera_sub_view.rs"
+name = "camera_crop"
+path = "examples/3d/camera_crop.rs"
 doc-scrape-examples = true
 
-[package.metadata.example.camera_sub_view]
+[package.metadata.example.camera_crop]
 name = "Camera sub view"
-description = "Demonstrates using different sub view effects on a camera"
+description = "Demonstrates using different camera crop effects"
 category = "3D Rendering"
 wasm = true
 

crates/bevy_render/src/camera/camera.rs

@@ -6,7 +6,7 @@ use super::{ClearColorConfig, Projection};
 use crate::{
     batching::gpu_preprocessing::{GpuPreprocessingMode, GpuPreprocessingSupport},
     camera::{CameraProjection, ManualTextureViewHandle, ManualTextureViews},
-    primitives::Frustum,
+    primitives::{Frustum, SubRect},
     render_asset::RenderAssets,
     render_graph::{InternedRenderSubGraph, RenderSubGraph},
     render_resource::TextureView,
@@ -112,55 +112,6 @@ impl Viewport {
     }
 }
 
-/// Settings to define a camera sub view.
-///
-/// When [`Camera::sub_camera_view`] is `Some`, only the sub-section of the
-/// image defined by `size` and `offset` (relative to the `full_size` of the
-/// whole image) is projected to the cameras viewport.
-///
-/// Take the example of the following multi-monitor setup:
-/// ```css
-/// ┌───┬───┐
-/// │ A │ B │
-/// ├───┼───┤
-/// │ C │ D │
-/// └───┴───┘
-/// ```
-/// If each monitor is 1920x1080, the whole image will have a resolution of
-/// 3840x2160. For each monitor we can use a single camera with a viewport of
-/// the same size as the monitor it corresponds to. To ensure that the image is
-/// cohesive, we can use a different sub view on each camera:
-/// - Camera A: `full_size` = 3840x2160, `size` = 1920x1080, `offset` = 0,0
-/// - Camera B: `full_size` = 3840x2160, `size` = 1920x1080, `offset` = 1920,0
-/// - Camera C: `full_size` = 3840x2160, `size` = 1920x1080, `offset` = 0,1080
-/// - Camera D: `full_size` = 3840x2160, `size` = 1920x1080, `offset` =
-///   1920,1080
-///
-/// However since only the ratio between the values is important, they could all
-/// be divided by 120 and still produce the same image. Camera D would for
-/// example have the following values:
-/// `full_size` = 32x18, `size` = 16x9, `offset` = 16,9
-#[derive(Debug, Clone, Copy, Reflect, PartialEq)]
-#[reflect(Clone, PartialEq, Default)]
-pub struct SubCameraView {
-    /// Size of the entire camera view
-    pub full_size: UVec2,
-    /// Offset of the sub camera
-    pub offset: Vec2,
-    /// Size of the sub camera
-    pub size: UVec2,
-}
-
-impl Default for SubCameraView {
-    fn default() -> Self {
-        Self {
-            full_size: UVec2::new(1, 1),
-            offset: Vec2::new(0., 0.),
-            size: UVec2::new(1, 1),
-        }
-    }
-}
-
 /// Information about the current [`RenderTarget`].
 #[derive(Default, Debug, Clone)]
 pub struct RenderTargetInfo {
@@ -180,7 +131,7 @@ pub struct ComputedCameraValues {
     target_info: Option<RenderTargetInfo>,
     // size of the `Viewport`
     old_viewport_size: Option<UVec2>,
-    old_sub_camera_view: Option<SubCameraView>,
+    old_crop: Option<SubRect>,
 }
 
 /// How much energy a `Camera3d` absorbs from incoming light.
@@ -370,8 +321,9 @@ pub struct Camera {
     pub msaa_writeback: bool,
     /// The clear color operation to perform on the render target.
     pub clear_color: ClearColorConfig,
-    /// If set, this camera will be a sub camera of a large view, defined by a [`SubCameraView`].
-    pub sub_camera_view: Option<SubCameraView>,
+    /// If set, this camera will still render to its entire viewport, but its projection will
+    /// adjust to only render the specified [`SubRect`] of the total view.
+    pub crop: Option<SubRect>,
 }
 
 fn warn_on_no_render_graph(world: DeferredWorld, HookContext { entity, caller, .. }: HookContext) {
@@ -392,7 +344,7 @@ impl Default for Camera {
             hdr: false,
             msaa_writeback: true,
             clear_color: Default::default(),
-            sub_camera_view: None,
+            crop: None,
         }
     }
 }
@@ -992,7 +944,7 @@ pub fn camera_system(
                 || camera.is_added()
                 || camera_projection.is_changed()
                 || camera.computed.old_viewport_size != viewport_size
-                || camera.computed.old_sub_camera_view != camera.sub_camera_view
+                || camera.computed.old_crop != camera.crop
             {
                 let new_computed_target_info = normalized_target.get_render_target_info(
                     windows,
@@ -1038,7 +990,7 @@ pub fn camera_system(
                 if let Some(size) = camera.logical_viewport_size() {
                     if size.x != 0.0 && size.y != 0.0 {
                         camera_projection.update(size.x, size.y);
-                        camera.computed.clip_from_view = match &camera.sub_camera_view {
+                        camera.computed.clip_from_view = match &camera.crop {
                             Some(sub_view) => {
                                 camera_projection.get_clip_from_view_for_sub(sub_view)
                             }
@@ -1053,8 +1005,8 @@ pub fn camera_system(
             camera.computed.old_viewport_size = viewport_size;
         }
 
-        if camera.computed.old_sub_camera_view != camera.sub_camera_view {
-            camera.computed.old_sub_camera_view = camera.sub_camera_view;
+        if camera.computed.old_crop != camera.crop {
+            camera.computed.old_crop = camera.crop;
         }
     }
 }

crates/bevy_render/src/camera/projection.rs

@@ -1,6 +1,9 @@
 use core::fmt::Debug;
 
-use crate::{primitives::Frustum, view::VisibilitySystems};
+use crate::{
+    primitives::{Frustum, SubRect},
+    view::VisibilitySystems,
+};
 use bevy_app::{App, Plugin, PostStartup, PostUpdate};
 use bevy_asset::AssetEventSystems;
 use bevy_derive::{Deref, DerefMut};
@@ -70,7 +73,7 @@ pub trait CameraProjection {
     fn get_clip_from_view(&self) -> Mat4;
 
     /// Generate the projection matrix for a [`SubCameraView`](super::SubCameraView).
-    fn get_clip_from_view_for_sub(&self, sub_view: &super::SubCameraView) -> Mat4;
+    fn get_clip_from_view_for_sub(&self, sub_rect: &SubRect) -> Mat4;
 
     /// When the area this camera renders to changes dimensions, this method will be automatically
     /// called. Use this to update any projection properties that depend on the aspect ratio or
@@ -261,7 +264,7 @@ impl CameraProjection for Projection {
         }
     }
 
-    fn get_clip_from_view_for_sub(&self, sub_view: &super::SubCameraView) -> Mat4 {
+    fn get_clip_from_view_for_sub(&self, sub_view: &SubRect) -> Mat4 {
         match self {
             Projection::Perspective(projection) => projection.get_clip_from_view_for_sub(sub_view),
             Projection::Orthographic(projection) => projection.get_clip_from_view_for_sub(sub_view),
@@ -337,14 +340,14 @@ impl CameraProjection for PerspectiveProjection {
         Mat4::perspective_infinite_reverse_rh(self.fov, self.aspect_ratio, self.near)
     }
 
-    fn get_clip_from_view_for_sub(&self, sub_view: &super::SubCameraView) -> Mat4 {
-        let full_width = sub_view.full_size.x as f32;
-        let full_height = sub_view.full_size.y as f32;
-        let sub_width = sub_view.size.x as f32;
-        let sub_height = sub_view.size.y as f32;
-        let offset_x = sub_view.offset.x;
+    fn get_clip_from_view_for_sub(&self, sub_rect: &SubRect) -> Mat4 {
+        let full_width = sub_rect.full_size.x as f32;
+        let full_height = sub_rect.full_size.y as f32;
+        let sub_width = sub_rect.size.x as f32;
+        let sub_height = sub_rect.size.y as f32;
+        let offset_x = sub_rect.offset.x;
         // Y-axis increases from top to bottom
-        let offset_y = full_height - (sub_view.offset.y + sub_height);
+        let offset_y = full_height - (sub_rect.offset.y + sub_height);
 
         let full_aspect = full_width / full_height;
 
@@ -565,13 +568,13 @@ impl CameraProjection for OrthographicProjection {
         )
     }
 
-    fn get_clip_from_view_for_sub(&self, sub_view: &super::SubCameraView) -> Mat4 {
-        let full_width = sub_view.full_size.x as f32;
-        let full_height = sub_view.full_size.y as f32;
-        let offset_x = sub_view.offset.x;
-        let offset_y = sub_view.offset.y;
-        let sub_width = sub_view.size.x as f32;
-        let sub_height = sub_view.size.y as f32;
+    fn get_clip_from_view_for_sub(&self, sub_rect: &SubRect) -> Mat4 {
+        let full_width = sub_rect.full_size.x as f32;
+        let full_height = sub_rect.full_size.y as f32;
+        let offset_x = sub_rect.offset.x;
+        let offset_y = sub_rect.offset.y;
+        let sub_width = sub_rect.size.x as f32;
+        let sub_height = sub_rect.size.y as f32;
 
         let full_aspect = full_width / full_height;