camera: make camera transform in world coordinates instead of the inverse

crates/bevy_core/src/transform/face_toward.rs

@@ -0,0 +1,19 @@
+use glam::{Vec3, Mat4};
+
+pub trait FaceToward {
+    fn face_toward(eye: Vec3, center: Vec3, up: Vec3) -> Self;
+}
+
+impl FaceToward for Mat4 {
+    fn face_toward(eye: Vec3, center: Vec3, up: Vec3) -> Self {
+        let forward = (eye - center).normalize();
+        let right = up.cross(forward).normalize();
+        let up = forward.cross(right);
+        Mat4::from_cols(
+            right.extend(0.0),
+            up.extend(0.0),
+            forward.extend(0.0),
+            eye.extend(1.0),
+        )
+    }
+}

crates/bevy_core/src/transform/mod.rs

@@ -1,5 +1,7 @@
 mod hierarchy;
 mod world_builder;
+mod face_toward;
 
 pub use hierarchy::*;
 pub use world_builder::*;
+pub use face_toward::*;

crates/bevy_pbr/src/light.rs

@@ -41,7 +41,7 @@ impl LightRaw {
             far: light.depth.end,
         };
 
-        let proj = perspective.get_view_matrix() * *transform;
+        let proj = perspective.get_projection_matrix() * *transform;
         let (x, y, z) = translation.0.into();
         LightRaw {
             proj: proj.to_cols_array_2d(),

crates/bevy_render/src/camera/camera.rs

@@ -7,7 +7,7 @@ use legion::{prelude::*, storage::Component};
 
 #[derive(Default, Debug, Properties)]
 pub struct Camera {
-    pub view_matrix: Mat4,
+    pub projection_matrix: Mat4,
     pub name: Option<String>,
 }
 
@@ -29,7 +29,7 @@ pub fn camera_system<T: CameraProjection + Component>() -> Box<dyn Schedulable>
             if let Some(window) = windows.get(event.id) {
                 for (mut camera, mut camera_projection) in query.iter_mut(world) {
                     camera_projection.update(window.width as usize, window.height as usize);
-                    camera.view_matrix = camera_projection.get_view_matrix();
+                    camera.projection_matrix = camera_projection.get_projection_matrix();
                 }
             }
         }
@@ -40,7 +40,7 @@ pub fn camera_system<T: CameraProjection + Component>() -> Box<dyn Schedulable>
                     primary_window_resized_event.width,
                     primary_window_resized_event.height,
                 );
-                camera.view_matrix = camera_projection.get_view_matrix();
+                camera.projection_matrix = camera_projection.get_projection_matrix();
             }
         }
     })

crates/bevy_render/src/camera/projection.rs

@@ -3,7 +3,7 @@ use glam::Mat4;
 use serde::{Deserialize, Serialize};
 
 pub trait CameraProjection {
-    fn get_view_matrix(&self) -> Mat4;
+    fn get_projection_matrix(&self) -> Mat4;
     fn update(&mut self, width: usize, height: usize);
 }
 
@@ -16,7 +16,7 @@ pub struct PerspectiveProjection {
 }
 
 impl CameraProjection for PerspectiveProjection {
-    fn get_view_matrix(&self) -> Mat4 {
+    fn get_projection_matrix(&self) -> Mat4 {
         let projection = Mat4::perspective_rh_gl(self.fov, self.aspect_ratio, self.near, self.far);
         projection
     }
@@ -55,7 +55,7 @@ pub struct OrthographicProjection {
 }
 
 impl CameraProjection for OrthographicProjection {
-    fn get_view_matrix(&self) -> Mat4 {
+    fn get_projection_matrix(&self) -> Mat4 {
         let projection = Mat4::orthographic_rh(
             self.left,
             self.right,

crates/bevy_render/src/camera/visible_entities.rs

@@ -7,12 +7,13 @@ use legion::{
     systems::{Query, SubWorld},
 };
 
+#[derive(Debug)]
 pub struct VisibleEntity {
     pub entity: Entity,
     pub order: FloatOrd,
 }
 
-#[derive(Default)]
+#[derive(Default, Debug)]
 pub struct VisibleEntities {
     pub value: Vec<VisibleEntity>,
 }
@@ -41,8 +42,8 @@ pub fn visible_entities_system(
 
             let order = if let Some(transform) = world.get_component::<Transform>(entity) {
                 let position = transform.value.w_axis().truncate();
-                // smaller distances are sorted to lower indices by using the negative distance from the camera 
-                FloatOrd(-(camera_position - position).length())
+                // smaller distances are sorted to lower indices by using the distance from the camera 
+                FloatOrd((camera_position - position).length())
             } else {
                 let order = FloatOrd(no_transform_order);
                 no_transform_order += 0.1;
@@ -54,7 +55,7 @@ pub fn visible_entities_system(
             })
         }
 
-        visible_entities.value.sort_by_key(|e| e.order)
+        visible_entities.value.sort_by_key(|e| e.order);
 
         // TODO: check for big changes in visible entities len() vs capacity() (ex: 2x) and resize to prevent holding unneeded memory
     }

crates/bevy_render/src/render_graph/nodes/camera_node.rs

@@ -81,7 +81,7 @@ impl SystemNode for CameraNode {
             };
 
             let matrix_size = std::mem::size_of::<[[f32; 4]; 4]>();
-            let camera_matrix: [f32; 16] = (camera.view_matrix * transform.value).to_cols_array();
+            let camera_matrix: [f32; 16] = (camera.projection_matrix * transform.value.inverse()).to_cols_array();
 
             let tmp_buffer = render_resource_context.create_buffer_mapped(
                 BufferInfo {

crates/bevy_render/src/render_graph/nodes/main_pass_node.rs

@@ -91,17 +91,17 @@ impl Node for MainPassNode {
                 TextureAttachment::Id(input.get(input_index).unwrap().get_texture().unwrap());
         }
 
-        for camera_name in self.cameras.iter() {
-            let visible_entities = if let Some(camera_entity) = active_cameras.get(camera_name) {
-                world.get_component::<VisibleEntities>(camera_entity).unwrap()
-            } else {
-                continue;
-            };
+        render_context.begin_pass(
+            &self.descriptor,
+            &render_resource_bindings,
+            &mut |render_pass| {
+                for camera_name in self.cameras.iter() {
+                    let visible_entities = if let Some(camera_entity) = active_cameras.get(camera_name) {
+                        world.get_component::<VisibleEntities>(camera_entity).unwrap()
+                    } else {
+                        continue;
+                    };
 
-            render_context.begin_pass(
-                &self.descriptor,
-                &render_resource_bindings,
-                &mut |render_pass| {
                     let mut draw_state = DrawState::default();
                     for visible_entity in visible_entities.iter() {
                         let draw = if let Some(draw) = world.get_component::<Draw>(visible_entity.entity) {
@@ -170,9 +170,9 @@ impl Node for MainPassNode {
                             }
                         }
                     }
-                },
-            );
-        }
+                }
+            },
+        );
     }
 }
 

crates/bevy_transform/src/components/transform.rs

@@ -27,7 +27,7 @@ impl Transform {
 
     /// This creates a new `LocalToWorld` transform with the `sync` field set to `false`.
     /// While `sync` is false, position, rotation, and scale components will not be synced to the transform.
-    /// This is helpful if you want to manually set the transform to a value (ex: Mat4::look_at_rh)  
+    /// This is helpful if you want to manually set the transform to a value (ex: Mat4::face_toward)  
     #[inline(always)]
     pub fn new_sync_disabled(value: Mat4) -> Self {
         Transform { value, sync: false }

examples/3d/3d_scene.rs

@@ -50,7 +50,7 @@ fn setup(
         })
         // camera
         .add_entity(PerspectiveCameraEntity {
-            transform: Transform::new_sync_disabled(Mat4::look_at_rh(
+            transform: Transform::new_sync_disabled(Mat4::face_toward(
                 Vec3::new(3.0, 8.0, 5.0),
                 Vec3::new(0.0, 0.0, 0.0),
                 Vec3::new(0.0, 0.0, 1.0),

examples/3d/load_model.rs

@@ -39,7 +39,7 @@ fn setup(
         })
         // camera
         .add_entity(PerspectiveCameraEntity {
-            transform: Transform::new_sync_disabled(Mat4::look_at_rh(
+            transform: Transform::new_sync_disabled(Mat4::face_toward(
                 Vec3::new(2.0, -6.0, 2.0),
                 Vec3::new(0.0, 0.0, 0.0),
                 Vec3::new(0.0, 0.0, 1.0),

examples/3d/parenting.rs

@@ -53,7 +53,7 @@ fn setup(
         })
         // camera
         .add_entity(PerspectiveCameraEntity {
-            transform: Transform::new_sync_disabled(Mat4::look_at_rh(
+            transform: Transform::new_sync_disabled(Mat4::face_toward(
                 Vec3::new(5.0, 10.0, 10.0),
                 Vec3::new(0.0, 0.0, 0.0),
                 Vec3::new(0.0, 0.0, 1.0),

examples/3d/spawner.rs

@@ -63,7 +63,7 @@ fn setup(
         })
         // camera
         .add_entity(PerspectiveCameraEntity {
-            transform: Transform::new_sync_disabled(Mat4::look_at_rh(
+            transform: Transform::new_sync_disabled(Mat4::face_toward(
                 Vec3::new(3.0, 8.0, 5.0),
                 Vec3::new(0.0, 0.0, 0.0),
                 Vec3::new(0.0, 0.0, 1.0),

examples/3d/texture.rs

@@ -67,7 +67,7 @@ fn setup(
         })
         // camera
         .add_entity(PerspectiveCameraEntity {
-            transform: Transform::new_sync_disabled(Mat4::look_at_rh(
+            transform: Transform::new_sync_disabled(Mat4::face_toward(
                 Vec3::new(3.0, -8.0, 5.0),
                 Vec3::new(0.0, 0.0, 0.0),
                 Vec3::new(0.0, 0.0, 1.0),

examples/3d/z_sort_debug.rs

@@ -24,9 +24,11 @@ fn camera_order_color_system(
 ) {
     for (_camera, visible_entities) in camera_query.iter(world) {
         for visible_entity in visible_entities.iter() {
-            if let Some(material_handle) = world.get_component::<Handle<StandardMaterial>>(visible_entity.entity) {
+            if let Some(material_handle) =
+                world.get_component::<Handle<StandardMaterial>>(visible_entity.entity)
+            {
                 let material = materials.get_mut(&material_handle).unwrap();
-                let value = 1.0 - (20.0 + visible_entity.order.0) / 7.0;
+                let value = 1.0 - (visible_entity.order.0 - 10.0) / 7.0;
                 material.albedo = Color::rgb(value, value, value);
             }
         }
@@ -40,7 +42,6 @@ fn setup(
     mut materials: ResMut<Assets<StandardMaterial>>,
 ) {
     let cube_handle = meshes.add(Mesh::from(shape::Cube { size: 1.0 }));
-
     command_buffer
         .build()
         // parent cube
@@ -83,7 +84,7 @@ fn setup(
         })
         // camera
         .add_entity(PerspectiveCameraEntity {
-            transform: Transform::new_sync_disabled(Mat4::look_at_rh(
+            transform: Transform::new_sync_disabled(Mat4::face_toward(
                 Vec3::new(5.0, 10.0, 10.0),
                 Vec3::new(0.0, 0.0, 0.0),
                 Vec3::new(0.0, 0.0, 1.0),

examples/app/dynamic_plugin_loading/example_plugin/src/lib.rs

@@ -35,7 +35,7 @@ fn setup(
         })
         // camera
         .add_entity(PerspectiveCameraEntity {
-            transform: Transform::new_sync_disabled(Mat4::look_at_rh(
+            transform: Transform::new_sync_disabled(Mat4::face_toward(
                 Vec3::new(3.0, 8.0, 5.0),
                 Vec3::new(0.0, 0.0, 0.0),
                 Vec3::new(0.0, 0.0, 1.0),

examples/asset/asset_loading.rs

@@ -72,7 +72,7 @@ fn setup(
         })
         // camera
         .add_entity(PerspectiveCameraEntity {
-            transform: Transform::new_sync_disabled(Mat4::look_at_rh(
+            transform: Transform::new_sync_disabled(Mat4::face_toward(
                 Vec3::new(0.0, -10.0, 3.0),
                 Vec3::new(0.0, 0.0, 0.0),
                 Vec3::new(0.0, 0.0, 1.0),

examples/asset/hot_asset_reloading.rs

@@ -47,7 +47,7 @@ fn setup(
         })
         // camera
         .add_entity(PerspectiveCameraEntity {
-            transform: Transform::new_sync_disabled(Mat4::look_at_rh(
+            transform: Transform::new_sync_disabled(Mat4::face_toward(
                 Vec3::new(2.0, -6.0, 2.0),
                 Vec3::new(0.0, 0.0, 0.0),
                 Vec3::new(0.0, 0.0, 1.0),

examples/shader/shader_custom_material.rs

@@ -103,7 +103,7 @@ fn setup(
         })
         // camera
         .add_entity(PerspectiveCameraEntity {
-            transform: Transform::new_sync_disabled(Mat4::look_at_rh(
+            transform: Transform::new_sync_disabled(Mat4::face_toward(
                 Vec3::new(3.0, 8.0, 5.0),
                 Vec3::new(0.0, 0.0, 0.0),
                 Vec3::new(0.0, 0.0, 1.0),

examples/shader/shader_defs.rs

@@ -146,7 +146,7 @@ fn setup(
         })
         // camera
         .add_entity(PerspectiveCameraEntity {
-            transform: Transform::new_sync_disabled(Mat4::look_at_rh(
+            transform: Transform::new_sync_disabled(Mat4::face_toward(
                 Vec3::new(3.0, 8.0, 5.0),
                 Vec3::new(0.0, 0.0, 0.0),
                 Vec3::new(0.0, 0.0, 1.0),

examples/ui/ui.rs

@@ -48,7 +48,7 @@ fn setup(
         // })
         // // 3d camera
         // .add_entity(CameraEntity {
-        //     transform: Transform(Mat4::look_at_rh(
+        //     transform: Transform(Mat4::face_toward(
         //         Vec3::new(3.0, 8.0, 5.0),
         //         Vec3::new(0.0, 0.0, 0.0),
         //         Vec3::new(0.0, 0.0, 1.0),

src/prelude.rs

@@ -6,7 +6,7 @@ pub use crate::{
     asset::{AddAsset, AssetEvent, AssetServer, Assets, Handle},
     core::{
         time::{Time, Timer},
-        transform::{CommandBufferBuilderSource, WorldBuilder, WorldBuilderSource},
+        transform::{CommandBufferBuilderSource, WorldBuilder, WorldBuilderSource, FaceToward},
     },
     diagnostic::DiagnosticsPlugin,
     input::{keyboard::KeyCode, mouse::MouseButton, Input},