Eevee: Improve compilation time (reduce branching).

This patch reduce the branching in the lamp loop, improving compilation time
noticeably (2372ms to 1785ms for the default shader).

This should not change the appearance of the shader.

Performance impact is negligeable.

1 files changed, 23 insertions, 2 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 4e65834e528..ac1dd071a29 100644
--- a/source/blender/draw/engines/eevee/shaders/lit_surface_frag.glsl
+++ b/source/blender/draw/engines/eevee/shaders/lit_surface_frag.glsl
@@ -182,6 +182,17 @@ void CLOSURE_NAME(
 	/* -------------------- SCENE LAMPS LIGHTING ---------------------- */
 	/* ---------------------------------------------------------------- */
 
+#ifdef CLOSURE_GLOSSY
+	vec2 lut_uv = lut_coords(dot(N, V), roughness);
+	vec4 ltc_mat = texture(utilTex, vec3(lut_uv, 0.0)).rgba;
+#endif
+
+#ifdef CLOSURE_CLEARCOAT
+	vec2 lut_uv_clear = lut_coords(dot(C_N, V), C_roughness);
+	vec4 ltc_mat_clear = texture(utilTex, vec3(lut_uv_clear, 0.0)).rgba;
+	vec3 out_spec_clear = vec3(0.0);
+#endif
+
 	for (int i = 0; i < MAX_LIGHT && i < laNumLight; ++i) {
 		LightData ld = lights_data[i];
 
@@ -200,14 +211,24 @@ void CLOSURE_NAME(
 	#endif
 
 	#ifdef CLOSURE_GLOSSY
-		out_spec += l_color_vis * light_specular(ld, N, V, l_vector, roughnessSquared, f0) * ld.l_spec;
+		out_spec += l_color_vis * light_specular(ld, ltc_mat, N, V, l_vector) * ld.l_spec;
 	#endif
 
 	#ifdef CLOSURE_CLEARCOAT
-		out_spec += l_color_vis * light_specular(ld, C_N, V, l_vector, C_roughnessSquared, f0) * C_intensity * ld.l_spec;
+		out_spec_clear += l_color_vis * light_specular(ld, ltc_mat_clear, C_N, V, l_vector) * C_intensity * ld.l_spec;
 	#endif
 	}
 
+#ifdef CLOSURE_GLOSSY
+	vec3 brdf_lut_lamps = texture(utilTex, vec3(lut_uv, 1.0)).rgb;
+	out_spec *= F_area(f0, brdf_lut_lamps.xy) * brdf_lut_lamps.z;
+#endif
+
+#ifdef CLOSURE_CLEARCOAT
+	vec3 brdf_lut_lamps_clear = texture(utilTex, vec3(lut_uv_clear, 1.0)).rgb;
+	out_spec_clear *= F_area(f0, brdf_lut_lamps_clear.xy) * brdf_lut_lamps_clear.z;
+	out_spec += out_spec_clear;
+#endif
 
 	/* ---------------------------------------------------------------- */
 	/* ---------------- SPECULAR ENVIRONMENT LIGHTING ----------------- */