bevy_gltf: Add support for loading lights (#3506)

# Objective

- Add support for loading lights from glTF 2.0 files

## Solution

- This adds support for the KHR_punctual_lights extension which supports point, directional, and spot lights, though we don't yet support spot lights.
- Inserting light bundles when creating scenes required registering some more light bundle component types.

crates/bevy_gltf/Cargo.toml

@@ -24,7 +24,12 @@ bevy_scene = { path = "../bevy_scene", version = "0.5.0" }
 bevy_log = { path = "../bevy_log", version = "0.5.0" }
 
 # other
-gltf = { version = "0.16.0", default-features = false, features = ["utils", "names", "KHR_materials_unlit"] }
+gltf = { version = "0.16.0", default-features = false, features = [
+    "KHR_lights_punctual",
+    "KHR_materials_unlit",
+    "names",
+    "utils",
+] }
 thiserror = "1.0"
 anyhow = "1.0.4"
 base64 = "0.13.0"

crates/bevy_gltf/src/loader.rs

@@ -6,7 +6,10 @@ use bevy_core::Name;
 use bevy_ecs::world::World;
 use bevy_log::warn;
 use bevy_math::{Mat4, Vec3};
-use bevy_pbr::{AlphaMode, PbrBundle, StandardMaterial};
+use bevy_pbr::{
+    AlphaMode, DirectionalLight, DirectionalLightBundle, PbrBundle, PointLight, PointLightBundle,
+    StandardMaterial,
+};
 use bevy_render::{
     camera::{
         Camera, CameraPlugin, CameraProjection, OrthographicProjection, PerspectiveProjection,
@@ -550,6 +553,42 @@ fn load_node(
             }
         }
 
+        if let Some(light) = gltf_node.light() {
+            match light.kind() {
+                gltf::khr_lights_punctual::Kind::Directional => {
+                    parent.spawn_bundle(DirectionalLightBundle {
+                        directional_light: DirectionalLight {
+                            color: Color::from(light.color()),
+                            // NOTE: KHR_punctual_lights defines the intensity units for directional
+                            // lights in lux (lm/m^2) which is what we need.
+                            illuminance: light.intensity(),
+                            ..Default::default()
+                        },
+                        ..Default::default()
+                    });
+                }
+                gltf::khr_lights_punctual::Kind::Point => {
+                    parent.spawn_bundle(PointLightBundle {
+                        point_light: PointLight {
+                            color: Color::from(light.color()),
+                            // NOTE: KHR_punctual_lights defines the intensity units for point lights in
+                            // candela (lm/sr) which is luminous intensity and we need luminous power.
+                            // For a point light, luminous power = 4 * pi * luminous intensity
+                            intensity: light.intensity() * std::f32::consts::PI * 4.0,
+                            range: light.range().unwrap_or(20.0),
+                            radius: light.range().unwrap_or(0.0),
+                            ..Default::default()
+                        },
+                        ..Default::default()
+                    });
+                }
+                gltf::khr_lights_punctual::Kind::Spot {
+                    inner_cone_angle: _inner_cone_angle,
+                    outer_cone_angle: _outer_cone_angle,
+                } => warn!("Spot lights are not yet supported."),
+            }
+        }
+
         // append other nodes
         for child in gltf_node.children() {
             if let Err(err) = load_node(&child, parent, load_context, buffer_data) {

crates/bevy_pbr/src/bundle.rs

@@ -1,6 +1,7 @@
 use crate::{DirectionalLight, PointLight, SpecializedMaterial, StandardMaterial};
 use bevy_asset::Handle;
-use bevy_ecs::{bundle::Bundle, component::Component};
+use bevy_ecs::{bundle::Bundle, component::Component, reflect::ReflectComponent};
+use bevy_reflect::Reflect;
 use bevy_render::{
     mesh::Mesh,
     primitives::{CubemapFrusta, Frustum},
@@ -37,8 +38,10 @@ impl<M: SpecializedMaterial> Default for MaterialMeshBundle<M> {
     }
 }
 
-#[derive(Component, Clone, Debug, Default)]
+#[derive(Component, Clone, Debug, Default, Reflect)]
+#[reflect(Component)]
 pub struct CubemapVisibleEntities {
+    #[reflect(ignore)]
     data: [VisibleEntities; 6],
 }
 

crates/bevy_pbr/src/lib.rs

@@ -67,7 +67,10 @@ impl Plugin for PbrPlugin {
             Shader::from_wgsl(include_str!("render/depth.wgsl")),
         );
 
-        app.add_plugin(MeshRenderPlugin)
+        app.register_type::<CubemapVisibleEntities>()
+            .register_type::<DirectionalLight>()
+            .register_type::<PointLight>()
+            .add_plugin(MeshRenderPlugin)
             .add_plugin(MaterialPlugin::<StandardMaterial>::default())
             .init_resource::<AmbientLight>()
             .init_resource::<DirectionalLightShadowMap>()

crates/bevy_pbr/src/light.rs

@@ -2,6 +2,7 @@ use std::collections::HashSet;
 
 use bevy_ecs::prelude::*;
 use bevy_math::{Mat4, UVec2, UVec3, Vec2, Vec3, Vec3Swizzles, Vec4, Vec4Swizzles};
+use bevy_reflect::Reflect;
 use bevy_render::{
     camera::{Camera, CameraProjection, OrthographicProjection},
     color::Color,
@@ -33,7 +34,8 @@ use crate::{
 /// | 4000 | 300 |    | 75-100 | 40.5  |
 ///
 /// Source: [Wikipedia](https://en.wikipedia.org/wiki/Lumen_(unit)#Lighting)
-#[derive(Component, Debug, Clone, Copy)]
+#[derive(Component, Debug, Clone, Copy, Reflect)]
+#[reflect(Component)]
 pub struct PointLight {
     pub color: Color,
     pub intensity: f32,
@@ -104,7 +106,8 @@ impl Default for PointLightShadowMap {
 /// | 32,000–100,000    | Direct sunlight                                |
 ///
 /// Source: [Wikipedia](https://en.wikipedia.org/wiki/Lux)
-#[derive(Component, Debug, Clone)]
+#[derive(Component, Debug, Clone, Reflect)]
+#[reflect(Component)]
 pub struct DirectionalLight {
     pub color: Color,
     /// Illuminance in lux

crates/bevy_render/src/color/mod.rs

@@ -617,6 +617,12 @@ impl From<[f32; 4]> for Color {
     }
 }
 
+impl From<[f32; 3]> for Color {
+    fn from([r, g, b]: [f32; 3]) -> Self {
+        Color::rgb(r, g, b)
+    }
+}
+
 impl From<Color> for Vec4 {
     fn from(color: Color) -> Self {
         let color: [f32; 4] = color.into();

crates/bevy_render/src/lib.rs

@@ -33,7 +33,7 @@ use crate::{
     camera::CameraPlugin,
     color::Color,
     mesh::MeshPlugin,
-    primitives::Frustum,
+    primitives::{CubemapFrusta, Frustum},
     render_graph::RenderGraph,
     render_resource::{RenderPipelineCache, Shader, ShaderLoader},
     renderer::render_system,
@@ -141,7 +141,8 @@ impl Plugin for RenderPlugin {
             .init_asset_loader::<ShaderLoader>()
             .init_resource::<ScratchRenderWorld>()
             .register_type::<Color>()
-            .register_type::<Frustum>();
+            .register_type::<Frustum>()
+            .register_type::<CubemapFrusta>();
         let render_pipeline_cache = RenderPipelineCache::new(device.clone());
         let asset_server = app.world.get_resource::<AssetServer>().unwrap().clone();
 

crates/bevy_render/src/primitives/mod.rs

@@ -144,8 +144,10 @@ impl Frustum {
     }
 }
 
-#[derive(Component, Debug, Default)]
+#[derive(Component, Debug, Default, Reflect)]
+#[reflect(Component)]
 pub struct CubemapFrusta {
+    #[reflect(ignore)]
     pub frusta: [Frustum; 6],
 }