Eeshlo AO patch, revised

- Ambient Occlusion is a more sophisticated ambient trick, which takes
  nearby faces into account by firing a hemisphere of shadow-rays
  around. AKA 'dirt shader'.
- Eeshlo made it a Lamp type, which doesn't fit well. I've moved the
  settings to the World menu, and let the Material->ambient value control
  the amount it contributes
- currently, the AO value is added/subtracted/mixed with the 'diffuse'
  factor while shading, before it is multiplied with Material color

Buttons are in new Panel 'Amb Occ" in F8 menu. Note:

- "Dist:" by shortening the length of rays you get subtler effects and it
  renders faster too
- "DistF:" the attennuation factor gives control over how the 'shadow'
  spreads out.

Further it's just raytracing, so tends to be slooooow.... :)
Here same tricks as for other raytraced scenes apply, especially try to
keep the environment as small as possible (exclude faces from Octree by
giving them no Material Traceable).

I still have to think over a couple of aspects, will await feedback on it:
- AO color? Now it just adds 'white'
- other sampling patterns? I tried dithering, which was so-so
- method of controlling final 'samples' in F10? Might be useful for other
  oversampling too (area light) to have it reacting to a percentage or so..

1 files changed, 17 insertions, 1 deletions

diff --git a/source/blender/makesdna/DNA_world_types.h b/source/blender/makesdna/DNA_world_types.h
index efa17af4996..c325c2d1b8a 100644
--- a/source/blender/makesdna/DNA_world_types.h
+++ b/source/blender/makesdna/DNA_world_types.h
@@ -91,8 +91,13 @@ typedef struct World {
 	float starsize, starmindist;
 	float stardist, starcolnoise;
 	
+	/* unused now: DOF */
 	short dofsta, dofend, dofmin, dofmax;
-
+	
+	/* ambient occlusion */
+	float aodist, aodistfac;
+	short aomode, aosamp, aomix, aototsamp;
+	
 	int physicsEngine;
 
 	struct Ipo *ipo;
@@ -117,6 +122,17 @@ typedef struct World {
 #define WO_STARS               2
 #define WO_DOF                 4
 #define WO_ACTIVITY_CULLING	   8
+#define WO_AMB_OCC	   		  16
+
+/* aomix */
+#define WO_AOADD	0
+#define WO_AOSUB	1
+#define WO_AOADDSUB	2
+
+/* aomode (use distances & random sampling modes) */
+#define WO_AODIST		1
+#define WO_AORNDSMP		2
+
 
 /* mapto */
 #define WOMAP_BLEND		1