ADD: IBL added

shaders/deferred_lighting.frag

@@ -10,6 +10,33 @@ layout(set=1, binding=0) uniform sampler2D posTex;
 layout(set=1, binding=1) uniform sampler2D normalTex;
 layout(set=1, binding=2) uniform sampler2D albedoTex;
 layout(set=2, binding=0) uniform sampler2D shadowTex[4];
+// IBL (set=3): specular prefiltered cube, diffuse irradiance cube, BRDF LUT
+layout(set=3, binding=0) uniform sampler2D iblSpec2D;
+layout(set=3, binding=1) uniform sampler2D iblBRDF;
+layout(std140, set=3, binding=2) uniform IBL_SH { vec4 sh[9]; } iblSH;
+
+vec3 sh_eval_irradiance(vec3 n)
+{
+    float x=n.x, y=n.y, z=n.z;
+    const float c0=0.2820947918;
+    const float c1=0.4886025119;
+    const float c2=1.0925484306;
+    const float c3=0.3153915653;
+    const float c4=0.5462742153;
+    float Y[9];
+    Y[0]=c0; Y[1]=c1*y; Y[2]=c1*z; Y[3]=c1*x; Y[4]=c2*x*y; Y[5]=c2*y*z; Y[6]=c3*(3.0*z*z-1.0); Y[7]=c2*x*z; Y[8]=c4*(x*x-y*y);
+    vec3 r=vec3(0.0);
+    for (int i=0;i<9;++i) r += iblSH.sh[i].rgb * Y[i];
+    return r;
+}
+
+vec2 dir_to_equirect(vec3 d)
+{
+    d = normalize(d);
+    float phi = atan(d.z, d.x);
+    float theta = acos(clamp(d.y, -1.0, 1.0));
+    return vec2(phi * (0.15915494309) + 0.5, theta * (0.31830988618));
+}
 // TLAS for ray query (optional, guarded by sceneData.rtOptions.x)
 #ifdef GL_EXT_ray_query
 layout(set=0, binding=1) uniform accelerationStructureEXT topLevelAS;
@@ -338,7 +365,17 @@ void main(){
     vec3 irradiance = sceneData.sunlightColor.rgb * sceneData.sunlightColor.a * NdotL * visibility;
 
     vec3 color = (kD * albedo / PI + specular) * irradiance;
-    color += albedo * sceneData.ambientColor.rgb;
+
+    // Image-Based Lighting: split-sum approximation
+    vec3 R = reflect(-V, N);
+    float levels = float(textureQueryLevels(iblSpec2D));
+    float lod = clamp(roughness * max(levels - 1.0, 0.0), 0.0, max(levels - 1.0, 0.0));
+    vec2 uv = dir_to_equirect(R);
+    vec3 prefiltered = textureLod(iblSpec2D, uv, lod).rgb;
+    vec2 brdf = texture(iblBRDF, vec2(max(dot(N, V), 0.0), roughness)).rg;
+    vec3 specIBL = prefiltered * (F0 * brdf.x + brdf.y);
+    vec3 diffIBL = (1.0 - metallic) * albedo * sh_eval_irradiance(N);
+    color += diffIBL + specIBL;
 
     outColor = vec4(color, 1.0);
-}
+}