EEVEE: Ambient Occlusion: Refactor

- Fix noise/banding artifact on distant geometry.
- Fix overshadowing on un-occluded surfaces at grazing angle producing "fresnel"
  like shadowing. Some of it still appears but this is caused to the low number
  of horizons per pixel.
- Improve performance by using a fixed number of samples and fixing the
  sampling area size. A better sampling pattern is planned to recover
  the lost precision on large AO radius.
- Improved normal reconstruction for the AO pass.
- Improve Bent Normal reconstruction resulting in less faceted look on
  smoothed geometry.
- Add Thickness heuristic to avoid overshadowing of thin objects.
  Factor is currently hardcoded.
- Add bent normal support to Glossy reflections.
- Change Glossy occlusion to give less light leaks from lightprobes.
  It can overshadow on smooth surface but this should be mitigated by
  using SSR.
- Use Bent Normal for rough Glossy surfaces.
- Occlusion is now correctly evaluated for each BSDF. However this does make
  everything slower. This is mitigated by the fact the search is a lot faster
  than before.

1 files changed, 6 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 0213ba2622b..d02fd27f35f 100644
--- a/source/blender/draw/intern/shaders/common_math_lib.glsl
+++ b/source/blender/draw/intern/shaders/common_math_lib.glsl
@@ -122,6 +122,12 @@ vec3 safe_normalize(vec3 v)
   return v / len;
 }
 
+vec3 normalize_len(vec3 v, out float len)
+{
+  len = length(v);
+  return v / len;
+}
+
 /** \} */
 
 /* ---------------------------------------------------------------------- */