refactor examples

lib/src/shaders/standard_shader.wgsl

@@ -96,7 +96,8 @@ struct FrameUniforms {
 };
 
 struct ObjectUniform {
-    model: mat4x4<f32>,
+    model: mat4x4<f32>,   // 64 bytes (offset 0)
+    emissive: vec4<f32>,  // 16 bytes (offset 64): rgb = color, a = intensity (can be > 1.0 in HDR)
 };
 
 @group(0) @binding(0) var<uniform> frame: FrameUniforms;
@@ -147,9 +148,10 @@ fn fs_main(in: VertexOutput) -> @location(0) vec4<f32> {
     let texel = textureSample(diffuse_texture, texture_sampler, in.uv);
     let base = texel.rgb * in.color.rgb;
 
-    // Flat (unlit) mode : pas d'éclairage, texel * couleur du vertex telle quelle.
+    // Flat (unlit) mode : pas d'éclairage, texel * couleur du vertex + emissive.
     if (frame.options.x != 0u) {
-        return vec4<f32>(base, in.color.a);
+        let emissive_contrib = base * object.emissive.rgb * object.emissive.a;
+        return vec4<f32>(base + emissive_contrib, in.color.a);
     }
 
     let n = normalize(in.normal);
@@ -203,7 +205,10 @@ fn fs_main(in: VertexOutput) -> @location(0) vec4<f32> {
     }
 
     let lit = base * (ambient + diffuse) * compute_shadow(in.world_pos, n);
-    return vec4<f32>(lit, in.color.a);
+    // Étape 22 (6.2): emissive — added to the lit result (independent of lights/shadows).
+    // Zero emissive (default) → no change (non-regression). In HDR, intensity > 1.0 glows.
+    let emissive_contrib = base * object.emissive.rgb * object.emissive.a;
+    return vec4<f32>(lit + emissive_contrib, in.color.a);
 }
 
 // Étape 14 (DRAFT 3.2, D5) : PCF shadow factor for this fragment. Reprojects the world position