EEVEE: Rewrite closure_lit_lib to reduce complexity

This rewrite improves:
- Code clarity: Less duplicated code and removes a few hacks.
- Compile time performance: Shader code was divided by 3 in average.
  I did not profile the compilation time but it is faster.
- Shading Perf: Noticed a 25% performance improvement on
  the shading pass with default dielectric principled bsdf.
- Fix Principled Tint being white if color is black
- It seems to have fixed issues on some drivers giving some incorect
  results.
- Changes Principled BSDF support to be less hacky.

1 files changed, 12 insertions, 0 deletions

diff --git a/source/blender/draw/intern/shaders/common_math_lib.glsl b/source/blender/draw/intern/shaders/common_math_lib.glsl
index a82e0b5a5e9..84d93cc3965 100644
--- a/source/blender/draw/intern/shaders/common_math_lib.glsl
+++ b/source/blender/draw/intern/shaders/common_math_lib.glsl
@@ -72,6 +72,9 @@ float sum(vec4 v) { return dot(vec4(1.0), v); }
 float avg(vec2 v) { return dot(vec2(1.0 / 2.0), v); }
 float avg(vec3 v) { return dot(vec3(1.0 / 3.0), v); }
 float avg(vec4 v) { return dot(vec4(1.0 / 4.0), v); }
+
+float sqr(float v) { return v * v; }
+
 /* clang-format on */
 
 #define saturate(a) clamp(a, 0.0, 1.0)
@@ -93,6 +96,15 @@ float len_squared(vec3 a)
   return dot(a, a);
 }
 
+vec3 safe_normalize(vec3 v)
+{
+  float len = length(v);
+  if (isnan(len) || len == 0.0) {
+    return vec3(1.0, 0.0, 0.0);
+  }
+  return v / len;
+}
+
 /** \} */
 
 /* ---------------------------------------------------------------------- */