Merge back a few cloth solver fixes from the render branch:

* Disable openmp for dot product, this gives different results each
  time due to non-commutative floating point add.
* Disable openmp with few vertices, the extra thread overhead only
  slows things down then.
* Replace the hack that would divide stepsPerFrame and then set it
  back, now it simply uses the timescale in the collision function.
  This was incorrect because stepsPerFrame is an int, but we don't
  want this to be rounded.
* Extra out of bounds check for hair velocity smoothing grid.

1 files changed, 15 insertions, 17 deletions

diff --git a/source/blender/blenkernel/intern/collision.c b/source/blender/blenkernel/intern/collision.c
index ffd504f5945..a77ac9b8e24 100644
--- a/source/blender/blenkernel/intern/collision.c
+++ b/source/blender/blenkernel/intern/collision.c
@@ -59,7 +59,7 @@ Collision modifier code start
 /* step is limited from 0 (frame start position) to 1 (frame end position) */
 void collision_move_object ( CollisionModifierData *collmd, float step, float prevstep )
 {
-	float tv[3] = {0,0,0};
+	float tv[3] = {0, 0, 0};
 	unsigned int i = 0;
 
 	for ( i = 0; i < collmd->numverts; i++ )
@@ -69,6 +69,7 @@ void collision_move_object ( CollisionModifierData *collmd, float step, float pr
 		VECADDS ( collmd->current_xnew[i].co, collmd->x[i].co, tv, step );
 		VECSUB ( collmd->current_v[i].co, collmd->current_xnew[i].co, collmd->current_x[i].co );
 	}
+
 	bvhtree_update_from_mvert ( collmd->bvhtree, collmd->mfaces, collmd->numfaces, collmd->current_x, collmd->current_xnew, collmd->numverts, 1 );
 }
 
@@ -527,7 +528,7 @@ int cloth_collision_response_static ( ClothModifierData *clmd, CollisionModifier
 			float magtangent = 0, repulse = 0, d = 0;
 			double impulse = 0.0;
 			float vrel_t_pre[3];
-			float temp[3];
+			float temp[3], spf;
 
 			// calculate tangential velocity
 			VECCOPY ( temp, collpair->normal );
@@ -565,10 +566,12 @@ int cloth_collision_response_static ( ClothModifierData *clmd, CollisionModifier
 
 			// Apply repulse impulse if distance too short
 			// I_r = -min(dt*kd, m(0,1d/dt - v_n))
+			spf = (float)clmd->sim_parms->stepsPerFrame / clmd->sim_parms->timescale;
+
 			d = clmd->coll_parms->epsilon*8.0/9.0 + epsilon2*8.0/9.0 - collpair->distance;
-			if ( ( magrelVel < 0.1*d*clmd->sim_parms->stepsPerFrame ) && ( d > ALMOST_ZERO ) )
+			if ( ( magrelVel < 0.1*d*spf ) && ( d > ALMOST_ZERO ) )
 			{
-				repulse = MIN2 ( d*1.0/clmd->sim_parms->stepsPerFrame, 0.1*d*clmd->sim_parms->stepsPerFrame - magrelVel );
+				repulse = MIN2 ( d*1.0/spf, 0.1*d*spf - magrelVel );
 
 				// stay on the safe side and clamp repulse
 				if ( impulse > ALMOST_ZERO )
@@ -1541,20 +1544,15 @@ int cloth_bvh_objcollision (Object *ob, ClothModifierData * clmd, float step, fl
 			overlap = BLI_bvhtree_overlap ( cloth_bvh, collmd->bvhtree, &result );
 				
 			// go to next object if no overlap is there
-			if(!result || !overlap)
-			{
-				if ( overlap )
-					MEM_freeN ( overlap );
-				continue;
-			}
-			
-			/* check if collisions really happen (costly near check) */
-			cloth_bvh_objcollisions_nearcheck ( clmd, collmd, &collisions[i], &collisions_index[i], result, overlap);
-			
-			// resolve nearby collisions
-			ret += cloth_bvh_objcollisions_resolve ( clmd, collmd, collisions[i],  collisions_index[i]);
-			ret2 += ret;
+			if( result && overlap ) {
+				/* check if collisions really happen (costly near check) */
+				cloth_bvh_objcollisions_nearcheck ( clmd, collmd, &collisions[i], &collisions_index[i], result, overlap);
 			
+				// resolve nearby collisions
+				ret += cloth_bvh_objcollisions_resolve ( clmd, collmd, collisions[i],  collisions_index[i]);
+				ret2 += ret;
+			}
+
 			if ( overlap )
 				MEM_freeN ( overlap );
 		}