Add emissive

crates/bevy_gltf/src/loader.rs

@@ -331,6 +331,13 @@ fn load_material(material: &Material, load_context: &mut LoadContext) -> Handle<
             (occlusion_texture, false)
         };
 
+    let emissive = material.emissive_factor();
+    let emissive_texture = load_texture(
+        material.emissive_texture().map(|info| info.texture()),
+        load_context,
+        &mut dependencies,
+    );
+
     let color = pbr.base_color_factor();
     load_context.set_labeled_asset(
         &material_label,
@@ -344,6 +351,8 @@ fn load_material(material: &Material, load_context: &mut LoadContext) -> Handle<
             double_sided: material.double_sided(),
             occlusion_shares_metallic_roughness_texture,
             occlusion_texture,
+            emissive: Color::rgba(emissive[0], emissive[1], emissive[2], 1.0),
+            emissive_texture,
             unlit: material.unlit(),
             ..Default::default()
         })

crates/bevy_pbr/src/material.rs

@@ -37,6 +37,11 @@ pub struct StandardMaterial {
     pub occlusion_shares_metallic_roughness_texture: bool,
     #[shader_def]
     pub occlusion_texture: Option<Handle<Texture>>,
+    // Use a color for user friendliness even though we technically don't use .a
+    // Might be used in the future for exposure correction in HDR
+    pub emissive: Color,
+    #[shader_def]
+    pub emissive_texture: Option<Handle<Texture>>,
     #[shader_def]
     #[render_resources(ignore)]
     #[shader_def]
@@ -64,6 +69,8 @@ impl Default for StandardMaterial {
             double_sided: false,
             occlusion_shares_metallic_roughness_texture: false,
             occlusion_texture: None,
+            emissive: Color::BLACK,
+            emissive_texture: None,
             unlit: false,
         }
     }

crates/bevy_pbr/src/render_graph/pipeline/pbr.frag

@@ -107,6 +107,16 @@ layout(set = 3,
        binding = 11) uniform sampler StandardMaterial_occlusion_texture_sampler;
 #    endif
 
+layout(set = 3, binding = 12) uniform StandardMaterial_emissive {
+    vec4 emissive;
+};
+
+#    if defined(STANDARDMATERIAL_EMISSIVE_TEXTURE)
+layout(set = 3, binding = 13) uniform texture2D StandardMaterial_emissive_texture;
+layout(set = 3,
+       binding = 14) uniform sampler StandardMaterial_emissive_texture_sampler;
+#    endif
+
 #    define saturate(x) clamp(x, 0.0, 1.0)
 const float PI = 3.141592653589793;
 
@@ -315,6 +325,11 @@ void main() {
     float occlusion = 1.0;
 #    endif
 
+#    ifdef STANDARDMATERIAL_EMISSIVE_TEXTURE
+    // TODO use .a for exposure compensation in HDR
+    vec3 emissive.rgb *= texture(sampler2D(StandardMaterial_emissive_texture, StandardMaterial_emissive_texture_sampler), v_Uv).rgb;
+#    endif
+
     vec3 V = normalize(CameraPos.xyz - v_WorldPosition.xyz);
     // Neubelt and Pettineo 2013, "Crafting a Next-gen Material Pipeline for The Order: 1886"
     float NdotV = max(dot(N, V), 1e-4);
@@ -363,7 +378,9 @@ void main() {
     vec3 diffuse_ambient = EnvBRDFApprox(diffuseColor, 1.0, NdotV);
     vec3 specular_ambient = EnvBRDFApprox(F0, perceptual_roughness, NdotV);
 
-    output_color.rgb = light_accum + (diffuse_ambient + specular_ambient) * AmbientColor * occlusion;
+    output_color.rgb = light_accum;
+    output_color.rgb += (diffuse_ambient + specular_ambient) * AmbientColor * occlusion;
+    output_color.rgb += emissive.rgb * output_color.a;
 
     // tone_mapping
     output_color.rgb = reinhard_luminance(output_color.rgb);

examples/3d/pbr_textures.rs

@@ -38,6 +38,7 @@ fn setup(
                         })),
                         material: materials.add(StandardMaterial {
                             base_color: Color::YELLOW,
+                            emissive: Color::WHITE * 10.0f32,
                             ..Default::default()
                         }),
                         transform: Transform::default(),