vk: rt: fix incorrect basecolor brdf multiplication

PBR model used implies the following rules:
- for metals both diffuse and specular components should be tinted by
  material base color.
- for dielectrics, only diffuse should be tinted, specular should remain
  as is.

Partially fixes #666

ref/vk/shaders/bounce.comp

@@ -158,8 +158,6 @@ void computeBounce(ivec2 pix, vec3 direction, out vec3 diffuse, out vec3 specula
 	if (!getHit(pos, bounce_direction, payload))
 		return;
 
-	throughput *= payload.base_color_a.rgb;
-
 	// 4. Sample light sources
 	{
 		vec3 ldiffuse = vec3(0.);
@@ -172,9 +170,11 @@ void computeBounce(ivec2 pix, vec3 direction, out vec3 diffuse, out vec3 specula
 		hit_material.emissive = vec3(0.f);
 		hit_material.metalness = payload.material_rmxx.g;
 		hit_material.roughness = payload.material_rmxx.r;
-		computeLighting(hit_pos, hit_shading_normal, throughput, -bounce_direction, hit_material, ldiffuse, lspecular);
+		computeLighting(hit_pos, hit_shading_normal, -bounce_direction, hit_material, ldiffuse, lspecular);
+
+		vec3 background = payload.base_color_a.rgb * ldiffuse;
+		background += lspecular * mix(vec3(1.), payload.base_color_a.rgb, hit_material.metalness);
 
-		vec3 background = ldiffuse + lspecular;
 		vec3 emissive = vec3(0.);
 		traceSimpleBlending(pos, bounce_direction, payload.hit_t.w, emissive, background);
 		const vec3 final_color = emissive + background;

ref/vk/shaders/denoiser.comp

@@ -22,6 +22,7 @@ layout(set = 0, binding = 6, rgba16f) uniform readonly image2D emissive;
 
 layout(set = 0, binding = 7, rgba32f) uniform readonly image2D position_t;
 layout(set = 0, binding = 8, rgba16f) uniform readonly image2D normals_gs;
+layout(set = 0, binding = 9, rgba8) uniform readonly image2D material_rmxx;
 layout(set = 0, binding = 10, rgba32f) uniform readonly image2D geometry_prev_position;
 
 layout(set = 0, binding = 11) uniform UBO { UniformBuffer ubo; } ubo;
@@ -42,7 +43,6 @@ layout(set = 0, binding = 18) uniform sampler3D blue_noise_texture;
 #endif
 
 //layout(set = 0, binding = 19) uniform sampler2D textures[MAX_TEXTURES];
-//layout(set = 0, binding = 18, rgba8) uniform readonly image2D material_rmxx;
 
 
 const int INDIRECT_SCALE = 2;
@@ -243,11 +243,9 @@ void main() {
 		return;
 	}
 
-	vec3 colour = vec3(0.);
+	vec3 diffuse = c.direct_diffuse + c.indirect_diffuse;
+	vec3 specular = c.direct_specular + c.indirect_specular;
 	{
-		vec3 diffuse = c.direct_diffuse + c.indirect_diffuse;
-		vec3 specular = c.direct_specular + c.indirect_specular;
-
 //#define DISABLE_TEMPORAL_DENOISER
 #ifndef DISABLE_TEMPORAL_DENOISER
 		// TODO: need to extract reprojecting from this shader because reprojected stuff need svgf denoising pass after it
@@ -296,13 +294,18 @@ void main() {
 		imageStore(out_temporal_diffuse, pix, vec4(diffuse, depth));
 		imageStore(out_temporal_specular, pix, vec4(specular, 0./*unused*/));
 #endif // ifndef DISABLE_TEMPORAL_DENOISER
+	}
+
+	vec3 colour = vec3(0.);
+
+	if (ubo.ubo.debug_display_only != DEBUG_DISPLAY_LIGHTING) {
+		const vec3 base_color = SRGBtoLINEAR(imageLoad(base_color_a, pix).rgb);
+		colour = diffuse * base_color;
+		colour += specular * mix(vec3(1.), base_color, imageLoad(material_rmxx, pix).g);
+	} else {
 		colour = diffuse + specular;
 	}
 
-	if (ubo.ubo.debug_display_only != DEBUG_DISPLAY_LIGHTING) {
-		const vec4 base_color_a = SRGBtoLINEAR(imageLoad(base_color_a, pix));
-		colour *= base_color_a.rgb;
-	}
 	colour += imageLoad(emissive, pix).rgb;
 	colour = LINEARtoSRGB(colour);
 

ref/vk/shaders/light.glsl

@@ -11,7 +11,7 @@ const float shadow_offset_fudge = .1;
 #endif
 
 #if LIGHT_POINT
-void computePointLights(vec3 P, vec3 N, uint cluster_index, vec3 throughput, vec3 view_dir, MaterialProperties material, out vec3 diffuse, out vec3 specular) {
+void computePointLights(vec3 P, vec3 N, uint cluster_index, vec3 view_dir, MaterialProperties material, out vec3 diffuse, out vec3 specular) {
 	diffuse = specular = vec3(0.);
 
 	//diffuse = vec3(1.);//float(lights.m.num_point_lights) / 64.);
@@ -24,7 +24,7 @@ void computePointLights(vec3 P, vec3 N, uint cluster_index, vec3 throughput, vec
 	for (uint i = 0; i < lights.m.num_point_lights; ++i) {
 #endif
 
-		vec3 color = lights.m.point_lights[i].color_stopdot.rgb * throughput;
+		vec3 color = lights.m.point_lights[i].color_stopdot.rgb;
 		if (dot(color,color) < color_culling_threshold)
 			continue;
 
@@ -114,7 +114,7 @@ void computePointLights(vec3 P, vec3 N, uint cluster_index, vec3 throughput, vec
 }
 #endif
 
-void computeLighting(vec3 P, vec3 N, vec3 throughput, vec3 view_dir, MaterialProperties material, out vec3 diffuse, out vec3 specular) {
+void computeLighting(vec3 P, vec3 N, vec3 view_dir, MaterialProperties material, out vec3 diffuse, out vec3 specular) {
 	diffuse = specular = vec3(0.);
 
 	const ivec3 light_cell = ivec3(floor(P / LIGHT_GRID_CELL_SIZE)) - lights.m.grid_min_cell;
@@ -122,7 +122,7 @@ void computeLighting(vec3 P, vec3 N, vec3 throughput, vec3 view_dir, MaterialPro
 
 #ifdef USE_CLUSTERS
 	if (any(greaterThanEqual(light_cell, lights.m.grid_size)) || cluster_index >= MAX_LIGHT_CLUSTERS)
-		return; // throughput * vec3(1., 0., 0.);
+		return; // vec3(1., 0., 0.);
 #endif
 
 	//diffuse = specular = vec3(1.);
@@ -138,7 +138,7 @@ void computeLighting(vec3 P, vec3 N, vec3 throughput, vec3 view_dir, MaterialPro
 	//C += .3 * fract(vec3(light_cell) / 4.);
 
 #if LIGHT_POLYGON
-	sampleEmissiveSurfaces(P, N, throughput, view_dir, material, cluster_index, diffuse, specular);
+	sampleEmissiveSurfaces(P, N, view_dir, material, cluster_index, diffuse, specular);
 	// These constants are empirical. There's no known math reason behind them
 	diffuse /= 25.0;
 	specular /= 25.0;
@@ -146,7 +146,7 @@ void computeLighting(vec3 P, vec3 N, vec3 throughput, vec3 view_dir, MaterialPro
 
 #if LIGHT_POINT
 	vec3 ldiffuse = vec3(0.), lspecular = vec3(0.);
-	computePointLights(P, N, cluster_index, throughput, view_dir, material, ldiffuse, lspecular);
+	computePointLights(P, N, cluster_index, view_dir, material, ldiffuse, lspecular);
 	// These constants are empirical. There's no known math reason behind them
 	ldiffuse /= 4.;
 	lspecular /= 4.;

ref/vk/shaders/light_polygon.glsl

@@ -197,7 +197,7 @@ void sampleSinglePolygonLight(in vec3 P, in vec3 N, in vec3 view_dir, in SampleC
 
 #if 0
 // Sample random one
-void sampleEmissiveSurfaces(vec3 P, vec3 N, vec3 throughput, vec3 view_dir, MaterialProperties material, uint cluster_index, inout vec3 diffuse, inout vec3 specular) {
+void sampleEmissiveSurfaces(vec3 P, vec3 N, vec3 view_dir, MaterialProperties material, uint cluster_index, inout vec3 diffuse, inout vec3 specular) {
 	const uint num_polygons = uint(light_grid.clusters_[cluster_index].num_polygons);
 
 	if (num_polygons == 0)
@@ -215,7 +215,7 @@ void sampleEmissiveSurfaces(vec3 P, vec3 N, vec3 throughput, vec3 view_dir, Mate
 }
 
 #elif 1
-void sampleEmissiveSurfaces(vec3 P, vec3 N, vec3 throughput, vec3 view_dir, MaterialProperties material, uint cluster_index, inout vec3 diffuse, inout vec3 specular) {
+void sampleEmissiveSurfaces(vec3 P, vec3 N, vec3 view_dir, MaterialProperties material, uint cluster_index, inout vec3 diffuse, inout vec3 specular) {
 #if DO_ALL_IN_CLUSTER
 	const SampleContext ctx = buildSampleContext(P, N, view_dir);
 
@@ -256,8 +256,8 @@ void sampleEmissiveSurfaces(vec3 P, vec3 N, vec3 throughput, vec3 view_dir, Mate
 			const float estimate = light_sample_dir.w;
 			vec3 poly_diffuse = vec3(0.), poly_specular = vec3(0.);
 			evalSplitBRDF(N, light_sample_dir.xyz, view_dir, material, poly_diffuse, poly_specular);
-			diffuse += throughput * emissive * estimate * poly_diffuse;
-			specular += throughput * emissive * estimate * poly_specular;
+			diffuse += emissive * estimate * poly_diffuse;
+			specular += emissive * estimate * poly_specular;
 		}
 	}
 #else // DO_ALL_IN_CLUSTERS
@@ -310,8 +310,8 @@ void sampleEmissiveSurfaces(vec3 P, vec3 N, vec3 throughput, vec3 view_dir, Mate
 	const vec3 emissive = poly.emissive;
 	vec3 poly_diffuse = vec3(0.), poly_specular = vec3(0.);
 	evalSplitBRDF(N, normalize(poly.center-P), view_dir, material, poly_diffuse, poly_specular);
-	diffuse += throughput * emissive * total_contrib;
-	specular += throughput * emissive * total_contrib;
+	diffuse += emissive * total_contrib;
+	specular += emissive * total_contrib;
 #else
 	const SampleContext ctx = buildSampleContext(P, N, view_dir);
 	const PolygonLight poly = lights.m.polygons[selected - 1];
@@ -332,8 +332,8 @@ void sampleEmissiveSurfaces(vec3 P, vec3 N, vec3 throughput, vec3 view_dir, Mate
 		const float estimate = light_sample_dir.w;
 		vec3 poly_diffuse = vec3(0.), poly_specular = vec3(0.);
 		evalSplitBRDF(N, light_sample_dir.xyz, view_dir, material, poly_diffuse, poly_specular);
-		diffuse += throughput * emissive * estimate;
-		specular += throughput * emissive * estimate;
+		diffuse += emissive * estimate;
+		specular += emissive * estimate;
 	}
 #endif
 #endif

ref/vk/shaders/ray_light_direct.glsl

@@ -45,9 +45,8 @@ void main() {
 	vec3 geometry_normal, shading_normal;
 	readNormals(pix, geometry_normal, shading_normal);
 
-	const vec3 throughput = vec3(1.);
 	vec3 diffuse = vec3(0.), specular = vec3(0.);
-	computeLighting(pos + geometry_normal * .001, shading_normal, throughput, -direction, material, diffuse, specular);
+	computeLighting(pos + geometry_normal * .001, shading_normal, -direction, material, diffuse, specular);
 
 #if LIGHT_POINT
 	imageStore(out_light_point_diffuse, pix, vec4(diffuse, 0.f));