Followup fix Bugfix [#31629]: Cloth simulation collisions used still too high repulsions.

1 files changed, 10 insertions, 3 deletions

diff --git a/source/blender/blenkernel/intern/collision.c b/source/blender/blenkernel/intern/collision.c
index e680d9889cd..b90cc9d5958 100644
--- a/source/blender/blenkernel/intern/collision.c
+++ b/source/blender/blenkernel/intern/collision.c
@@ -302,6 +302,10 @@ static int cloth_collision_response_static ( ClothModifierData *clmd, CollisionM
 
 			// Apply repulse impulse if distance too short
 			// I_r = -min(dt*kd, m(0, 1d/dt - v_n))
+			// DG: this formula ineeds to be changed for this code since we apply impulses/repulses like this:
+			// v += impulse; x_new = x + v; 
+			// We don't use dt!!
+			// DG TODO: Fix usage of dt here!
 			spf = (float)clmd->sim_parms->stepsPerFrame / clmd->sim_parms->timescale;
 
 			d = clmd->coll_parms->epsilon*8.0f/9.0f + epsilon2*8.0f/9.0f - collpair->distance;
@@ -324,15 +328,18 @@ static int cloth_collision_response_static ( ClothModifierData *clmd, CollisionM
 		else
 		{
 			// Apply repulse impulse if distance too short
-			// I_r = -min(dt*kd, m(0, 1d/dt - v_n))
+			// I_r = -min(dt*kd, max(0, 1d/dt - v_n))
+			// DG: this formula ineeds to be changed for this code since we apply impulses/repulses like this:
+			// v += impulse; x_new = x + v; 
+			// We don't use dt!!
 			float spf = (float)clmd->sim_parms->stepsPerFrame / clmd->sim_parms->timescale;
 
 			float d = clmd->coll_parms->epsilon*8.0f/9.0f + epsilon2*8.0f/9.0f - collpair->distance;
 			if ( d > ALMOST_ZERO) {
 				// stay on the safe side and clamp repulse
-				float repulse = d*1.0f/spf;
+				float repulse = d;
 
-				float impulse = repulse / (3.0f * ( 1.0f + w1*w1 + w2*w2 + w3*w3 )); // original 2.0 / 0.25
+				float impulse = repulse / (( 1.0f + w1*w1 + w2*w2 + w3*w3 )); // original 2.0 / 0.25
 				VECADDMUL ( i1, collpair->normal,  impulse );
 				VECADDMUL ( i2, collpair->normal,  impulse );
 				VECADDMUL ( i3, collpair->normal,  impulse );