Eevee: Update LTC code

Main change are:
- the fresnel LUT is separated from the main GGX LUT.
- LUTs use sqrt(1.0 - NV) as roughness remapping. Improving precision and
  removes needs for acos().
- LTC LUT is normalized by matrix middle component. Improving precision.

1 files changed, 6 insertions, 6 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 3d5b8f6f975..99cca570b0b 100644
--- a/source/blender/draw/engines/eevee/shaders/lit_surface_frag.glsl
+++ b/source/blender/draw/engines/eevee/shaders/lit_surface_frag.glsl
@@ -198,12 +198,12 @@ void CLOSURE_NAME(
 	/* ---------------------------------------------------------------- */
 
 #ifdef CLOSURE_GLOSSY
-	vec2 lut_uv = lut_coords(dot(N, V), roughness);
+	vec2 lut_uv = lut_coords_ltc(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);
+	vec2 lut_uv_clear = lut_coords_ltc(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
@@ -241,13 +241,13 @@ void CLOSURE_NAME(
 	}
 
 #ifdef CLOSURE_GLOSSY
-	vec3 brdf_lut_lights = texture(utilTex, vec3(lut_uv, 1.0)).rgb;
-	out_spec *= F_area(f0, brdf_lut_lights.xy) * brdf_lut_lights.z;
+	vec2 brdf_lut_lights = texture(utilTex, vec3(lut_uv, 1.0)).ba;
+	out_spec *= F_area(f0, brdf_lut_lights.xy);
 #endif
 
 #ifdef CLOSURE_CLEARCOAT
-	vec3 brdf_lut_lights_clear = texture(utilTex, vec3(lut_uv_clear, 1.0)).rgb;
-	out_spec_clear *= F_area(vec3(0.04), brdf_lut_lights_clear.xy) * brdf_lut_lights_clear.z;
+	vec2 brdf_lut_lights_clear = texture(utilTex, vec3(lut_uv_clear, 1.0)).ba;
+	out_spec_clear *= F_area(vec3(0.04), brdf_lut_lights_clear.xy);
 	out_spec += out_spec_clear * C_intensity;
 #endif