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, 7 insertions, 1 deletions

diff --git a/source/blender/gpu/shaders/material/gpu_shader_material_ambient_occlusion.glsl b/source/blender/gpu/shaders/material/gpu_shader_material_ambient_occlusion.glsl
index d718cc3f4fe..f3eea9869e5 100644
--- a/source/blender/gpu/shaders/material/gpu_shader_material_ambient_occlusion.glsl
+++ b/source/blender/gpu/shaders/material/gpu_shader_material_ambient_occlusion.glsl
@@ -4,7 +4,13 @@ void node_ambient_occlusion(
 {
   vec3 bent_normal;
   vec4 rand = texelfetch_noise_tex(gl_FragCoord.xy);
-  result_ao = occlusion_compute(normalize(normal), viewPosition, rand, bent_normal);
+  OcclusionData data = occlusion_load(viewPosition, 1.0);
+
+  vec3 V = cameraVec;
+  vec3 N = normalize(normal);
+  vec3 Ng = safe_normalize(cross(dFdx(worldPosition), dFdy(worldPosition)));
+
+  result_ao = diffuse_occlusion(data, V, N, Ng);
   result_color = result_ao * color;
 }
 #else