Commit: 5c1d56517083de72c34f430355de846810f41870
Author: Lukas Tönne
Date: Tue Sep 2 12:49:55 2014 +0200
Branches: hair_immediate_fixes
https://developer.blender.org/rB5c1d56517083de72c34f430355de846810f41870
Fix for hair collision detection: need to use the second point of the
timestep segment.
This ensures the distance for a collision pair is the one of the current
point position, and the response gets calculated accordingly.
===================================================================
M source/blender/blenkernel/intern/collision.c
===================================================================
diff --git a/source/blender/blenkernel/intern/collision.c
b/source/blender/blenkernel/intern/collision.c
index 86ee3ed..bb5a94c 100644
--- a/source/blender/blenkernel/intern/collision.c
+++ b/source/blender/blenkernel/intern/collision.c
@@ -1065,116 +1065,6 @@ static bool
cloth_points_collision_response_static(ClothModifierData *clmd, Coll
cloth1->verts[collpair->ap1].impulse[i]
= impulse[i];
}
}
-
-#if 0
- /* If v_n_mag < 0 the edges are approaching each other. */
- if ( magrelVel > ALMOST_ZERO ) {
- /* Calculate Impulse magnitude to stop all motion in
normal direction. */
- float magtangent = 0, repulse = 0, d = 0;
- double impulse = 0.0;
- float vrel_t_pre[3];
- float temp[3], spf;
-
- /* calculate tangential velocity */
- copy_v3_v3 ( temp, collpair->normal );
- mul_v3_fl(temp, magrelVel);
- sub_v3_v3v3(vrel_t_pre, relativeVelocity, temp);
-
- /* Decrease in magnitude of relative tangential
velocity due to coulomb friction
- * in original formula "magrelVel" should be the
"change of relative velocity in normal direction" */
- magtangent = min_ff(clmd->coll_parms->friction * 0.01f
* magrelVel, len_v3(vrel_t_pre));
-
- /* Apply friction impulse. */
- if ( magtangent > ALMOST_ZERO ) {
- normalize_v3(vrel_t_pre);
-
- impulse = magtangent / ( 1.0f + w1*w1 + w2*w2 +
w3*w3 ); /* 2.0 * */
- VECADDMUL ( i1, vrel_t_pre, w1 * impulse );
- VECADDMUL ( i2, vrel_t_pre, w2 * impulse );
- VECADDMUL ( i3, vrel_t_pre, w3 * impulse );
- }
-
- /* Apply velocity stopping impulse
- * I_c = m * v_N / 2.0
- * no 2.0 * magrelVel normally, but looks nicer DG */
- impulse = magrelVel / ( 1.0 + w1*w1 + w2*w2 + w3*w3 );
-
- VECADDMUL ( i1, collpair->normal, w1 * impulse );
- cloth1->verts[collpair->ap1].impulse_count++;
-
- VECADDMUL ( i2, collpair->normal, w2 * impulse );
- cloth1->verts[collpair->ap2].impulse_count++;
-
- VECADDMUL ( i3, collpair->normal, w3 * impulse );
- cloth1->verts[collpair->ap3].impulse_count++;
-
- /* 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;
- if ( ( magrelVel < 0.1f*d*spf ) && ( d > ALMOST_ZERO )
) {
- repulse = MIN2 ( d*1.0f/spf, 0.1f*d*spf -
magrelVel );
-
- /* stay on the safe side and clamp repulse */
- if ( impulse > ALMOST_ZERO )
- repulse = min_ff( repulse, 5.0*impulse
);
- repulse = max_ff(impulse, repulse);
-
- 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 );
- }
-
- result = 1;
- }
- else {
- /* Apply repulse impulse if distance too short
- * 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 - (float)collpair->distance;
- if ( d > ALMOST_ZERO) {
- /* stay on the safe side and clamp repulse */
- float repulse = d*1.0f/spf;
-
- float impulse = repulse / ( 3.0f * ( 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 );
-
- cloth1->verts[collpair->ap1].impulse_count++;
- cloth1->verts[collpair->ap2].impulse_count++;
- cloth1->verts[collpair->ap3].impulse_count++;
-
- result = 1;
- }
- }
-
- if (result) {
- int i = 0;
-
- for (i = 0; i < 3; i++) {
- if (cloth1->verts[collpair->ap1].impulse_count
> 0 && ABS(cloth1->verts[collpair->ap1].impulse[i]) < ABS(i1[i]))
- cloth1->verts[collpair->ap1].impulse[i]
= i1[i];
-
- if (cloth1->verts[collpair->ap2].impulse_count
> 0 && ABS(cloth1->verts[collpair->ap2].impulse[i]) < ABS(i2[i]))
- cloth1->verts[collpair->ap2].impulse[i]
= i2[i];
-
- if (cloth1->verts[collpair->ap3].impulse_count
> 0 && ABS(cloth1->verts[collpair->ap3].impulse[i]) < ABS(i3[i]))
- cloth1->verts[collpair->ap3].impulse[i]
= i3[i];
- }
- }
-#endif
}
return result;
}
@@ -1210,7 +1100,12 @@ static CollPair *cloth_point_collpair(float p1[3], float
p2[3], MVert *mverts, i
collpair->bp2 = bp2;
collpair->bp3 = bp3;
- copy_v3_v3(collpair->pa, p1);
+ /* note: using the second point here, which is
+ * the current updated position that needs to be corrected
+ */
+ copy_v3_v3(collpair->pa, p2);
+ collpair->distance = dot_v3v3(fnor, vec) * lambda;
+
w[0] = 1.0f - uv[0] - uv[1];
w[1] = uv[0];
w[2] = uv[1];
@@ -1220,7 +1115,6 @@ static CollPair *cloth_point_collpair(float p1[3], float
p2[3], MVert *mverts, i
* it would probably not work with collision response
*/
copy_v3_v3(collpair->normal, fnor);
- collpair->distance = -dot_v3v3(fnor, vec) * (1.0f - lambda);
copy_v3_v3(collpair->vector, vec);
collpair->time = lambda;
collpair->flag = 0;
@@ -1238,7 +1132,7 @@ static CollPair* cloth_point_collision(ModifierData *md1,
ModifierData *md2,
/* Cloth *cloth = clmd->clothObject; */ /* UNUSED */
ClothVertex *vert = NULL;
MFace *face = NULL;
- MVert *mverts = collmd->xnew;
+ MVert *mverts = collmd->current_x;
vert = &clmd->clothObject->verts[overlap->indexA];
face = &collmd->mfaces[overlap->indexB];
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