Fixing confusing near and far fields in Camera (bevyengine#4457)

# Objective

- Fixes bevyengine#4456 

## Solution

- Removed the `near` and `far` fields from the camera and the views.

---

## Changelog

- Removed the `near` and `far` fields from the camera and the views.
- Removed the `ClusterFarZMode::CameraFarPlane` far z mode.

## Migration Guide

- Cameras no longer accept near and far values during initialization
- `ClusterFarZMode::Constant` should be used with the far value instead of `ClusterFarZMode::CameraFarPlane`

Author: AronDerenyi

assets/shaders/custom_material.vert

@@ -10,8 +10,6 @@ layout(set = 0, binding = 0) uniform CameraViewProj {
     mat4 InverseView;
     mat4 Projection;
     vec3 WorldPosition;
-    float near;
-    float far;
     float width;
     float height;
 };

crates/bevy_gltf/src/loader.rs

@@ -746,8 +746,6 @@ fn load_node(
 
                 node.insert(Camera {
                     projection_matrix: orthographic_projection.get_projection_matrix(),
-                    near: orthographic_projection.near,
-                    far: orthographic_projection.far,
                     ..Default::default()
                 });
                 node.insert(orthographic_projection);
@@ -767,8 +765,6 @@ fn load_node(
                 }
                 node.insert(Camera {
                     projection_matrix: perspective_projection.get_projection_matrix(),
-                    near: perspective_projection.near,
-                    far: perspective_projection.far,
                     ..Default::default()
                 });
                 node.insert(perspective_projection);

crates/bevy_pbr/src/light.rs

@@ -217,8 +217,6 @@ pub enum SimulationLightSystems {
 /// rendering
 #[derive(Debug, Copy, Clone)]
 pub enum ClusterFarZMode {
-    /// Use the camera far-plane to determine the z-depth of the furthest cluster layer
-    CameraFarPlane,
     /// Calculate the required maximum z-depth based on currently visible lights.
     /// Makes better use of available clusters, speeding up GPU lighting operations
     /// at the expense of some CPU time and using more indices in the cluster light
@@ -758,7 +756,6 @@ pub(crate) fn assign_lights_to_clusters(
         let is_orthographic = camera.projection_matrix.w_axis.w == 1.0;
 
         let far_z = match config.far_z_mode() {
-            ClusterFarZMode::CameraFarPlane => camera.far,
             ClusterFarZMode::MaxLightRange => {
                 let inverse_view_row_2 = inverse_view_transform.row(2);
                 lights
@@ -772,7 +769,17 @@ pub(crate) fn assign_lights_to_clusters(
             ClusterFarZMode::Constant(far) => far,
         };
         let first_slice_depth = match (is_orthographic, requested_cluster_dimensions.z) {
-            (true, _) => camera.near,
+            (true, _) => {
+                // NOTE: Based on glam's Mat4::orthographic_rh(), as used to calculate the orthographic projection
+                // matrix, we can calculate the projection's view-space near plane as follows:
+                // component 3,2 = r * near and 2,2 = r where r = 1.0 / (near - far)
+                // There is a caveat here that when calculating the projection matrix, near and far were swapped to give
+                // reversed z, consistent with the perspective projection. So,
+                // 3,2 = r * far and 2,2 = r where r = 1.0 / (far - near)
+                // rearranging r = 1.0 / (far - near), r * (far - near) = 1.0, r * far - 1.0 = r * near, near = (r * far - 1.0) / r
+                // = (3,2 - 1.0) / 2,2
+                (camera.projection_matrix.w_axis.z - 1.0) / camera.projection_matrix.z_axis.z
+            }
             (false, 1) => config.first_slice_depth().max(far_z),
             _ => config.first_slice_depth(),
         };

crates/bevy_pbr/src/render/light.rs

@@ -74,8 +74,6 @@ pub struct ExtractedDirectionalLight {
     shadows_enabled: bool,
     shadow_depth_bias: f32,
     shadow_normal_bias: f32,
-    near: f32,
-    far: f32,
 }
 
 pub type ExtractedDirectionalLightShadowMap = DirectionalLightShadowMap;
@@ -513,8 +511,6 @@ pub fn extract_lights(
                 shadow_normal_bias: directional_light.shadow_normal_bias
                     * directional_light_texel_size
                     * std::f32::consts::SQRT_2,
-                near: directional_light.shadow_projection.near,
-                far: directional_light.shadow_projection.far,
             },
             render_visible_entities,
         ));
@@ -861,8 +857,6 @@ pub fn prepare_lights(
                             height: point_light_shadow_map.size as u32,
                             transform: view_translation * *view_rotation,
                             projection: cube_face_projection,
-                            near: POINT_LIGHT_NEAR_Z,
-                            far: light.range,
                         },
                         RenderPhase::<Shadow>::default(),
                         LightEntity::Point {
@@ -946,8 +940,6 @@ pub fn prepare_lights(
                             height: directional_light_shadow_map.size as u32,
                             transform: GlobalTransform::from_matrix(view.inverse()),
                             projection,
-                            near: light.near,
-                            far: light.far,
                         },
                         RenderPhase::<Shadow>::default(),
                         LightEntity::Directional { light_entity },

crates/bevy_pbr/src/render/mesh_view_bind_group.wgsl

@@ -6,8 +6,6 @@ struct View {
     inverse_view: mat4x4<f32>;
     projection: mat4x4<f32>;
     world_position: vec3<f32>;
-    near: f32;
-    far: f32;
     width: f32;
     height: f32;
 };

crates/bevy_render/src/camera/bundle.rs

@@ -55,11 +55,7 @@ impl<M: Component + Default> PerspectiveCameraBundle<M> {
             perspective_projection.far(),
         );
         PerspectiveCameraBundle {
-            camera: Camera {
-                near: perspective_projection.near,
-                far: perspective_projection.far,
-                ..Default::default()
-            },
+            camera: Camera::default(),
             perspective_projection,
             visible_entities: VisibleEntities::default(),
             frustum,
@@ -99,11 +95,7 @@ impl OrthographicCameraBundle<Camera3d> {
             orthographic_projection.far(),
         );
         OrthographicCameraBundle {
-            camera: Camera {
-                near: orthographic_projection.near,
-                far: orthographic_projection.far,
-                ..Default::default()
-            },
+            camera: Camera::default(),
             orthographic_projection,
             visible_entities: VisibleEntities::default(),
             frustum,
@@ -160,11 +152,7 @@ impl OrthographicCameraBundle<Camera2d> {
             orthographic_projection.far(),
         );
         OrthographicCameraBundle {
-            camera: Camera {
-                near: orthographic_projection.near,
-                far: orthographic_projection.far,
-                ..Default::default()
-            },
+            camera: Camera::default(),
             orthographic_projection,
             visible_entities: VisibleEntities::default(),
             frustum,

crates/bevy_render/src/camera/camera.rs

@@ -36,8 +36,6 @@ pub struct Camera {
     pub target: RenderTarget,
     #[reflect(ignore)]
     pub depth_calculation: DepthCalculation,
-    pub near: f32,
-    pub far: f32,
 }
 
 #[derive(Debug, Clone, Reflect, PartialEq, Eq, Hash)]
@@ -333,8 +331,6 @@ pub fn extract_cameras<M: Component + Default>(
                         transform: *transform,
                         width: size.x,
                         height: size.y,
-                        near: camera.near,
-                        far: camera.far,
                     },
                     visible_entities.clone(),
                     M::default(),

crates/bevy_render/src/view/mod.rs

@@ -81,8 +81,6 @@ pub struct ExtractedView {
     pub transform: GlobalTransform,
     pub width: u32,
     pub height: u32,
-    pub near: f32,
-    pub far: f32,
 }
 
 #[derive(Clone, AsStd140)]
@@ -92,8 +90,6 @@ pub struct ViewUniform {
     inverse_view: Mat4,
     projection: Mat4,
     world_position: Vec3,
-    near: f32,
-    far: f32,
     width: f32,
     height: f32,
 }
@@ -157,8 +153,6 @@ fn prepare_view_uniforms(
                 inverse_view,
                 projection,
                 world_position: camera.transform.translation,
-                near: camera.near,
-                far: camera.far,
                 width: camera.width as f32,
                 height: camera.height as f32,
             }),

crates/bevy_sprite/src/mesh2d/mesh2d_view_bind_group.wgsl

@@ -6,8 +6,6 @@ struct View {
     inverse_view: mat4x4<f32>;
     projection: mat4x4<f32>;
     world_position: vec3<f32>;
-    near: f32;
-    far: f32;
     width: f32;
     height: f32;
 };

examples/tools/scene_viewer.rs

@@ -293,13 +293,7 @@ fn camera_spawn_check(
                     &transform.back(),
                     perspective_projection.far(),
                 );
-                let camera = Camera {
-                    near: perspective_projection.near,
-                    far: perspective_projection.far,
-                    ..default()
-                };
                 PerspectiveCameraBundle {
-                    camera,
                     perspective_projection,
                     frustum,
                     transform,