Eevee: Add Initial support for Principle BRDF.

Lots of things not working yet but it's comming.

3 files changed, 183 insertions, 8 deletions

diff --git a/source/blender/draw/engines/eevee/shaders/lit_surface_frag.glsl b/source/blender/draw/engines/eevee/shaders/lit_surface_frag.glsl
index 38ce8680bab..127a5167d0c 100644
--- a/source/blender/draw/engines/eevee/shaders/lit_surface_frag.glsl
+++ b/source/blender/draw/engines/eevee/shaders/lit_surface_frag.glsl
@@ -139,7 +139,7 @@ vec3 eevee_surface_lit(vec3 N, vec3 albedo, vec3 f0, float roughness, float ao)
 	}
 
 	/* World Diffuse */
-	if (diff_accum.a < 1.0 && grid_count > 0) {
+	if (diff_accum.a < 0.999 && grid_count > 0) {
 		vec3 diff = probe_evaluate_world_diff(bent_normal);
 		accumulate_light(diff, 1.0, diff_accum);
 	}
@@ -148,3 +148,155 @@ vec3 eevee_surface_lit(vec3 N, vec3 albedo, vec3 f0, float roughness, float ao)
 
 	return out_light;
 }
+
+/* ----------- CLEAR COAT -----------  */
+
+vec3 eevee_surface_clearcoat_lit(
+        vec3 N, vec3 albedo, vec3 f0, float roughness,
+        vec3 C_N, float C_intensity, float C_roughness, /* Clearcoat params */
+        float ao)
+{
+	roughness = clamp(roughness, 1e-8, 0.9999);
+	float roughnessSquared = roughness * roughness;
+	C_roughness = clamp(C_roughness, 1e-8, 0.9999);
+	float C_roughnessSquared = C_roughness * C_roughness;
+
+	vec3 V = cameraVec;
+	N = normalize(N);
+	C_N = normalize(C_N);
+
+	vec4 rand = texture(utilTex, vec3(gl_FragCoord.xy / LUT_SIZE, 2.0));
+
+	/* ---------------- SCENE LAMPS LIGHTING ----------------- */
+
+#ifdef HAIR_SHADER
+	vec3 norm_view = cross(V, N);
+	norm_view = normalize(cross(norm_view, N)); /* Normal facing view */
+#endif
+
+	vec3 diff = vec3(0.0);
+	vec3 spec = vec3(0.0);
+	for (int i = 0; i < MAX_LIGHT && i < light_count; ++i) {
+		LightData ld = lights_data[i];
+
+		vec4 l_vector; /* Non-Normalized Light Vector with length in last component. */
+		l_vector.xyz = ld.l_position - worldPosition;
+		l_vector.w = length(l_vector.xyz);
+
+		vec3 l_color_vis = ld.l_color * light_visibility(ld, worldPosition, l_vector);
+
+#ifdef HAIR_SHADER
+		vec3 norm_lamp, view_vec;
+		float occlu_trans, occlu;
+		light_hair_common(ld, N, V, l_vector, norm_view, occlu_trans, occlu, norm_lamp, view_vec);
+
+		diff += l_color_vis * light_diffuse(ld, -norm_lamp, V, l_vector) * occlu_trans;
+		spec += l_color_vis * light_specular(ld, N, view_vec, l_vector, roughnessSquared, f0) * occlu;
+		spec += l_color_vis * light_specular(ld, C_N, view_vec, l_vector, C_roughnessSquared, f0) * C_intensity * occlu;
+#else
+		diff += l_color_vis * light_diffuse(ld, N, V, l_vector);
+		spec += l_color_vis * light_specular(ld, N, V, l_vector, roughnessSquared, f0);
+		spec += l_color_vis * light_specular(ld, C_N, V, l_vector, C_roughnessSquared, f0) * C_intensity;
+#endif
+	}
+
+	/* Accumulate outgoing radiance */
+	vec3 out_light = diff * albedo + spec * float(specToggle);
+
+#ifdef HAIR_SHADER
+	N = -norm_view;
+#endif
+
+	/* ---------------- SPECULAR ENVIRONMENT LIGHTING ----------------- */
+
+	/* Accumulate light from all sources until accumulator is full. Then apply Occlusion and BRDF. */
+	vec4 spec_accum = vec4(0.0);
+	vec4 C_spec_accum = vec4(0.0);
+
+	/* Planar Reflections */
+	for (int i = 0; i < MAX_PLANAR && i < planar_count && spec_accum.a < 0.999; ++i) {
+		PlanarData pd = planars_data[i];
+
+		/* Fade on geometric normal. */
+		float fade = probe_attenuation_planar(pd, worldPosition, worldNormal);
+
+		if (fade > 0.0) {
+			vec3 spec = probe_evaluate_planar(float(i), pd, worldPosition, N, V, rand.a, cameraPos, roughness, fade);
+			accumulate_light(spec, fade, spec_accum);
+
+			vec3 C_spec = probe_evaluate_planar(float(i), pd, worldPosition, C_N, V, rand.a, cameraPos, C_roughness, fade);
+			accumulate_light(C_spec, fade, C_spec_accum);
+		}
+	}
+
+	/* Specular probes */
+	vec3 spec_dir = get_specular_dominant_dir(N, V, roughnessSquared);
+	vec3 C_spec_dir = get_specular_dominant_dir(C_N, V, C_roughnessSquared);
+
+	/* Starts at 1 because 0 is world probe */
+	for (int i = 1; i < MAX_PROBE && i < probe_count && spec_accum.a < 0.999; ++i) {
+		CubeData cd = probes_data[i];
+
+		float fade = probe_attenuation_cube(cd, worldPosition);
+
+		if (fade > 0.0) {
+			vec3 spec = probe_evaluate_cube(float(i), cd, worldPosition, spec_dir, roughness);
+			accumulate_light(spec, fade, spec_accum);
+
+			vec3 C_spec = probe_evaluate_cube(float(i), cd, worldPosition, C_spec_dir, C_roughness);
+			accumulate_light(C_spec, fade, C_spec_accum);
+		}
+	}
+
+	/* World Specular */
+	if (spec_accum.a < 0.999) {
+		vec3 spec = probe_evaluate_world_spec(spec_dir, roughness);
+		accumulate_light(spec, 1.0, spec_accum);
+
+		vec3 C_spec = probe_evaluate_world_spec(C_spec_dir, C_roughness);
+		accumulate_light(C_spec, 1.0, C_spec_accum);
+	}
+
+	/* Ambient Occlusion */
+	vec3 bent_normal;
+	float final_ao = occlusion_compute(N, viewPosition, ao, rand.rg, bent_normal);
+
+	/* Get Brdf intensity */
+	vec2 uv = lut_coords(dot(N, V), roughness);
+	vec2 brdf_lut = texture(utilTex, vec3(uv, 1.0)).rg;
+
+	out_light += spec_accum.rgb * F_ibl(f0, brdf_lut) * specular_occlusion(dot(N, V), final_ao, roughness) * float(specToggle);
+
+	uv = lut_coords(dot(C_N, V), C_roughness);
+	brdf_lut = texture(utilTex, vec3(uv, 1.0)).rg;
+
+	out_light += C_spec_accum.rgb * F_ibl(vec3(0.04), brdf_lut) * specular_occlusion(dot(C_N, V), final_ao, C_roughness) * float(specToggle) * C_intensity;
+
+	/* ---------------- DIFFUSE ENVIRONMENT LIGHTING ----------------- */
+
+	/* Accumulate light from all sources until accumulator is full. Then apply Occlusion and BRDF. */
+	vec4 diff_accum = vec4(0.0);
+
+	/* Start at 1 because 0 is world irradiance */
+	for (int i = 1; i < MAX_GRID && i < grid_count && diff_accum.a < 0.999; ++i) {
+		GridData gd = grids_data[i];
+
+		vec3 localpos;
+		float fade = probe_attenuation_grid(gd, worldPosition, localpos);
+
+		if (fade > 0.0) {
+			vec3 diff = probe_evaluate_grid(gd, worldPosition, bent_normal, localpos);
+			accumulate_light(diff, fade, diff_accum);
+		}
+	}
+
+	/* World Diffuse */
+	if (diff_accum.a < 0.999 && grid_count > 0) {
+		vec3 diff = probe_evaluate_world_diff(bent_normal);
+		accumulate_light(diff, 1.0, diff_accum);
+	}
+
+	out_light += diff_accum.rgb * albedo * gtao_multibounce(final_ao, albedo);
+
+	return out_light;
+}
\ No newline at end of file
diff --git a/source/blender/gpu/shaders/gpu_shader_material.glsl b/source/blender/gpu/shaders/gpu_shader_material.glsl
index abbcfc61518..e0e44bccfc0 100644
--- a/source/blender/gpu/shaders/gpu_shader_material.glsl
+++ b/source/blender/gpu/shaders/gpu_shader_material.glsl
@@ -2573,6 +2573,12 @@ vec3 rotate_vector(vec3 p, vec3 n, float theta) {
 	       );
 }
 
+void convert_metallic_to_specular(vec4 basecol, float metallic, float specular_fac, out vec4 diffuse, out vec4 f0)
+{
+	vec4 dielectric = vec4(0.034) * specular_fac * 2.0;
+	diffuse = mix(basecol, vec4(0.0), metallic);
+	f0 = mix(dielectric, basecol, metallic);
+}
 
 /*********** NEW SHADER NODES ***************/
 
@@ -2650,6 +2656,17 @@ void node_bsdf_principled(vec4 base_color, float subsurface, vec3 subsurface_rad
 	float specular_tint, float roughness, float anisotropic, float anisotropic_rotation, float sheen, float sheen_tint, float clearcoat,
 	float clearcoat_roughness, float ior, float transmission, float transmission_roughness, vec3 N, vec3 CN, vec3 T, vec3 I, out vec4 result)
 {
+#ifdef EEVEE_ENGINE
+	vec4 diffuse, f0;
+	convert_metallic_to_specular(base_color, metallic, specular, diffuse, f0);
+
+	/* Original value is 0.25 but this one seems to fit cycles better */
+	clearcoat *= 0.5;
+
+	vec3 surface_color = eevee_surface_clearcoat_lit(N, diffuse.rgb, f0.rgb, roughness, CN, clearcoat, clearcoat_roughness, 1.0);
+
+	result = vec4(surface_color, 1.0);
+#else
 	/* ambient light */
 	// TODO: set ambient light to an appropriate value
 	vec3 L = vec3(mix(0.1, 0.03, metallic)) * base_color.rgb;
@@ -2764,6 +2781,7 @@ void node_bsdf_principled(vec4 base_color, float subsurface, vec3 subsurface_rad
 	}
 
 	result = vec4(L, 1.0);
+#endif
 }
 
 void node_bsdf_translucent(vec4 color, vec3 N, out vec4 result)
@@ -3862,13 +3880,6 @@ void node_output_world(vec4 surface, vec4 volume, out vec4 result)
 	result = vec4(surface.rgb, backgroundAlpha);
 }
 
-void convert_metallic_to_specular(vec4 basecol, float metallic, float specular_fac, out vec4 diffuse, out vec4 f0)
-{
-	vec4 dielectric = vec4(0.034) * specular_fac * 2.0;
-	diffuse = mix(basecol, vec4(0.0), metallic);
-	f0 = mix(dielectric, basecol, metallic);
-}
-
 /* TODO : clean this ifdef mess */
 /* EEVEE output */
 #ifdef EEVEE_ENGINE
diff --git a/source/blender/nodes/shader/nodes/node_shader_bsdf_principled.c b/source/blender/nodes/shader/nodes/node_shader_bsdf_principled.c
index e0330d110ca..f34c0e603ac 100644
--- a/source/blender/nodes/shader/nodes/node_shader_bsdf_principled.c
+++ b/source/blender/nodes/shader/nodes/node_shader_bsdf_principled.c
@@ -65,6 +65,7 @@ static void node_shader_init_principled(bNodeTree *UNUSED(ntree), bNode *node)
 
 static int node_shader_gpu_bsdf_principled(GPUMaterial *mat, bNode *UNUSED(node), bNodeExecData *UNUSED(execdata), GPUNodeStack *in, GPUNodeStack *out)
 {
+#if 0 /* Old 2.7 glsl viewport */
 	// normal
 	if (!in[17].link)
 		in[17].link = GPU_builtin(GPU_VIEW_NORMAL);
@@ -76,6 +77,17 @@ static int node_shader_gpu_bsdf_principled(GPUMaterial *mat, bNode *UNUSED(node)
 		in[18].link = GPU_builtin(GPU_VIEW_NORMAL);
 	else
 		GPU_link(mat, "direction_transform_m4v3", in[18].link, GPU_builtin(GPU_VIEW_MATRIX), &in[18].link);
+#endif
+
+	/* Normals */
+	if (!in[17].link) {
+		GPU_link(mat, "world_normals_get", &in[17].link);
+	}
+
+	/* Clearcoat Normals */
+	if (!in[18].link) {
+		GPU_link(mat, "world_normals_get", &in[18].link);
+	}
 
 	return GPU_stack_link(mat, "node_bsdf_principled", in, out, GPU_builtin(GPU_VIEW_POSITION));
 }