Bugfix: Cloth did not work with Dynamic Paint.

Fix 1: Pinned vertices were never released when "unpinned" by Dynamic Paint. 

Fix 2: When pinning vertices during simulation, they would get "warped" to their original starting position of frame 1.

Thanks to MiikaH for pointing this out and also for providing the regression blend file: http://wiki.blender.org/uploads/a/ab/Cloth_dynamic_paint.blend

3 files changed, 75 insertions, 20 deletions

diff --git a/source/blender/blenkernel/BKE_cloth.h b/source/blender/blenkernel/BKE_cloth.h
index facbcb23dd6..30b3ab38c6f 100644
--- a/source/blender/blenkernel/BKE_cloth.h
+++ b/source/blender/blenkernel/BKE_cloth.h
@@ -57,7 +57,6 @@ struct CollisionTree;
 /* Bits to or into the ClothVertex.flags. */
 #define CLOTH_VERT_FLAG_PINNED 1
 #define CLOTH_VERT_FLAG_NOSELFCOLL 2 /* vertex NOT used for self collisions */
-#define CLOTH_VERT_FLAG_PINNED_EM 3
 
 /**
  * This structure describes a cloth object against which the
diff --git a/source/blender/blenkernel/intern/cloth.c b/source/blender/blenkernel/intern/cloth.c
index d1a4b33f8f8..af7afe7bf30 100644
--- a/source/blender/blenkernel/intern/cloth.c
+++ b/source/blender/blenkernel/intern/cloth.c
@@ -400,8 +400,18 @@ static int do_step_cloth(Object *ob, ClothModifierData *clmd, DerivedMesh *resul
 		copy_v3_v3(verts->txold, verts->x);
 
 		/* Get the current position. */
-		copy_v3_v3(verts->xconst, mvert[i].co);
-		mul_m4_v3(ob->obmat, verts->xconst);
+		if ((clmd->sim_parms->flags & CLOTH_SIMSETTINGS_FLAG_GOAL) && 
+			((!(cloth->verts[i].flags & CLOTH_VERT_FLAG_PINNED)) 
+			&& (cloth->verts[i].goal > ALMOST_ZERO)))
+		{
+			copy_v3_v3(verts->xconst, mvert[i].co);
+			mul_m4_v3(ob->obmat, verts->xconst);
+		}
+		else
+		{
+			/* This fixed animated goals not to jump back to "first frame position" */
+			copy_v3_v3(verts->xconst, verts->txold);
+		}
 	}
 
 	effectors = pdInitEffectors(clmd->scene, ob, NULL, clmd->sim_parms->effector_weights);
@@ -795,13 +805,21 @@ static void cloth_apply_vgroup ( ClothModifierData *clmd, DerivedMesh *dm )
 	
 	if (cloth_uses_vgroup(clmd)) {
 		for ( i = 0; i < numverts; i++, verts++ ) {
+
+			/* Reset Goal values to standard */
+			if ( clmd->sim_parms->flags & CLOTH_SIMSETTINGS_FLAG_GOAL )
+				verts->goal= clmd->sim_parms->defgoal;
+			else
+				verts->goal= 0.0f;
+
 			dvert = dm->getVertData ( dm, i, CD_MDEFORMVERT );
 			if ( dvert ) {
-				for ( j = 0; j < dvert->totweight; j++ ) {
 
+				for ( j = 0; j < dvert->totweight; j++ ) {
 					verts->flags &= ~CLOTH_VERT_FLAG_PINNED;
 					if (( dvert->dw[j].def_nr == (clmd->sim_parms->vgroup_mass-1)) && (clmd->sim_parms->flags & CLOTH_SIMSETTINGS_FLAG_GOAL )) {
 						verts->goal = dvert->dw [j].weight;
+
 						/* goalfac= 1.0f; */ /* UNUSED */
 						
 						/*
@@ -1082,6 +1100,20 @@ static void cloth_update_springs( ClothModifierData *clmd )
 		{
 			spring->stiffness = (cloth->verts[spring->kl].bend_stiff + cloth->verts[spring->ij].bend_stiff) / 2.0f;
 		}
+		else if(spring->type == CLOTH_SPRING_TYPE_GOAL)
+		{
+			/* Warning: Appending NEW goal springs does not work because implicit solver would need reset! */
+
+			/* Activate / Deactivate existing springs */
+			if ((!(cloth->verts[spring->ij].flags & CLOTH_VERT_FLAG_PINNED)) && (cloth->verts[spring->ij].goal > ALMOST_ZERO))
+			{
+				spring->flags &= ~CLOTH_SPRING_FLAG_DEACTIVATE;
+			}
+			else
+			{
+				spring->flags |= CLOTH_SPRING_FLAG_DEACTIVATE;
+			}
+		}
 		
 		search = search->next;
 	}
diff --git a/source/blender/blenkernel/intern/implicit.c b/source/blender/blenkernel/intern/implicit.c
index fdc3a8f4317..616214c21ff 100644
--- a/source/blender/blenkernel/intern/implicit.c
+++ b/source/blender/blenkernel/intern/implicit.c
@@ -120,7 +120,7 @@ typedef float lfVector[3];
 typedef struct fmatrix3x3 {
 	float m[3][3]; /* 3x3 matrix */
 	unsigned int c, r; /* column and row number */
-	int pinned; /* is this vertex allowed to move? */
+	/* int pinned; // is this vertex allowed to move? */
 	float n1, n2, n3; /* three normal vectors for collision constrains */
 	unsigned int vcount; /* vertex count */
 	unsigned int scount; /* spring count */ 
@@ -700,10 +700,32 @@ typedef struct Implicit_Data  {
 	fmatrix3x3 *A, *dFdV, *dFdX, *S, *P, *Pinv, *bigI, *M; 
 } Implicit_Data;
 
+/* Init constraint matrix */
+static void update_matrixS(ClothVertex *verts, int numverts, fmatrix3x3 *S)
+{
+	unsigned int pinned = 0;
+	int i = 0;
+
+	/* Clear matrix from old vertex constraints */
+	for(i = 0; i < S[0].vcount; i++)
+		S[i].c = S[i].r = 0;
+
+	/* Set new vertex constraints */
+	for (i = 0; i < numverts; i++) {
+		if (verts [i].flags & CLOTH_VERT_FLAG_PINNED) {
+			S[pinned].c = S[pinned].r = i;
+			pinned++;
+		}
+	}
+
+	// S is special and needs specific vcount and scount
+	S[0].vcount = pinned; 
+	S[0].scount = 0;
+}
+
 int implicit_init(Object *UNUSED(ob), ClothModifierData *clmd)
 {
 	unsigned int i = 0;
-	unsigned int pinned = 0;
 	Cloth *cloth = NULL;
 	ClothVertex *verts = NULL;
 	ClothSpring *spring = NULL;
@@ -743,24 +765,19 @@ int implicit_init(Object *UNUSED(ob), ClothModifierData *clmd)
 	id->dV = create_lfvector(cloth->numverts);
 	id->z = create_lfvector(cloth->numverts);
 	
-	for (i=0;i<cloth->numverts;i++) {
+	id->S[0].vcount = 0;
+
+	for (i = 0; i < cloth->numverts; i++) {
 		id->A[i].r = id->A[i].c = id->dFdV[i].r = id->dFdV[i].c = id->dFdX[i].r = id->dFdX[i].c = id->P[i].c = id->P[i].r = id->Pinv[i].c = id->Pinv[i].r = id->bigI[i].c = id->bigI[i].r = id->M[i].r = id->M[i].c = i;
 
-		if (verts [i].flags & CLOTH_VERT_FLAG_PINNED) {
-			id->S[pinned].pinned = 1;
-			id->S[pinned].c = id->S[pinned].r = i;
-			pinned++;
-		}
+		update_matrixS(verts, cloth->numverts, id->S);
 		
 		initdiag_fmatrixS(id->M[i].m, verts[i].mass);
 	}
 
-	// S is special and needs specific vcount and scount
-	id->S[0].vcount = pinned; id->S[0].scount = 0;
-
 	// init springs 
 	search = cloth->springs;
-	for (i=0;i<cloth->numsprings;i++) {
+	for (i = 0; i < cloth->numsprings; i++) {
 		spring = search->link;
 		
 		// dFdV_start[i].r = big_I[i].r = big_zero[i].r = 
@@ -784,6 +801,7 @@ int implicit_init(Object *UNUSED(ob), ClothModifierData *clmd)
 
 	return 1;
 }
+
 int	implicit_free(ClothModifierData *clmd)
 {
 	Implicit_Data *id;
@@ -1640,8 +1658,9 @@ static void cloth_calc_force(ClothModifierData *clmd, float UNUSED(frame), lfVec
 	search = cloth->springs;
 	while (search) {
 		// only handle active springs
-		// if (((clmd->sim_parms->flags & CSIMSETT_FLAG_TEARING_ENABLED) && !(springs[i].flags & CSPRING_FLAG_DEACTIVATE))|| !(clmd->sim_parms->flags & CSIMSETT_FLAG_TEARING_ENABLED)) {}
-		cloth_calc_spring_force(clmd, search->link, lF, lX, lV, dFdV, dFdX, time);
+		ClothSpring *spring = search->link;
+		if( !(spring->flags & CLOTH_SPRING_FLAG_DEACTIVATE))
+			cloth_calc_spring_force(clmd, search->link, lF, lX, lV, dFdV, dFdX, time);
 
 		search = search->next;
 	}
@@ -1650,8 +1669,9 @@ static void cloth_calc_force(ClothModifierData *clmd, float UNUSED(frame), lfVec
 	search = cloth->springs;
 	while (search) {
 		// only handle active springs
-		// if (((clmd->sim_parms->flags & CSIMSETT_FLAG_TEARING_ENABLED) && !(springs[i].flags & CSPRING_FLAG_DEACTIVATE))|| !(clmd->sim_parms->flags & CSIMSETT_FLAG_TEARING_ENABLED))	
-		cloth_apply_spring_force(clmd, search->link, lF, lX, lV, dFdV, dFdX);
+		ClothSpring *spring = search->link;
+		if (!(spring->flags & CLOTH_SPRING_FLAG_DEACTIVATE))
+			cloth_apply_spring_force(clmd, search->link, lF, lX, lV, dFdV, dFdX);
 		search = search->next;
 	}
 	// printf("\n");
@@ -1781,6 +1801,10 @@ int implicit_solver(Object *ob, float frame, ClothModifierData *clmd, ListBase *
 	int do_extra_solve;
 
 	if (clmd->sim_parms->flags & CLOTH_SIMSETTINGS_FLAG_GOAL) { /* do goal stuff */
+		
+		/* Update vertex constraints for pinned vertices */
+		update_matrixS(verts, cloth->numverts, id->S);
+
 		for (i = 0; i < numverts; i++) {
 			// update velocities with constrained velocities from pinned verts
 			if (verts [i].flags & CLOTH_VERT_FLAG_PINNED) {