Cloth self-collision

[geo6]

Was wondering if anyone might have some insight into how one would implement a cloth self collision feature into Bullet's softbody code. After Looking around a bit it looks like I need to implement vertex-face collision tests somewhere in the following function:

Code: Select all

void			btSoftBody::defaultCollisionHandler(btSoftBody* psb)
{
	const int cf=m_cfg.collisions&psb->m_cfg.collisions;
	switch(cf&fCollision::SVSmask)
	{
	case	fCollision::CL_SS:
		{
			
			//support self-collision if CL_SELF flag set
			if (this!=psb || psb->m_cfg.collisions&fCollision::CL_SELF)
			{
				btSoftColliders::CollideCL_SS	docollide;
				docollide.ProcessSoftSoft(this,psb);
			}
			
		}
		break;
	case	fCollision::VF_SS:
		{
			//only self-collision for Cluster, not Vertex-Face yet
			if (this!=psb)
			{
				btSoftColliders::CollideVF_SS	docollide;
				/* common					*/ 
				docollide.mrg=	getCollisionShape()->getMargin()+
					psb->getCollisionShape()->getMargin();
				/* psb0 nodes vs psb1 faces	*/ 
				docollide.psb[0]=this;
				docollide.psb[1]=psb;
				docollide.psb[0]->m_ndbvt.collideTT(	docollide.psb[0]->m_ndbvt.m_root,
					docollide.psb[1]->m_fdbvt.m_root,
					docollide);
				/* psb1 nodes vs psb0 faces	*/ 
				docollide.psb[0]=psb;
				docollide.psb[1]=this;
				docollide.psb[0]->m_ndbvt.collideTT(	docollide.psb[0]->m_ndbvt.m_root,
					docollide.psb[1]->m_fdbvt.m_root,
					docollide);
			}
		}
		break;
	default:
		{
			
		}
	}
}

Am I on the right track?

[steven]

i find this code below in the function btSoftRigidDynamicsWorld::internalSingleStepSimulation(btScalar timeStep) which seems to process self-collision.

Code: Select all

        //self collisions
	for (int i = 0; i < m_softBodies.size(); i++)
	{
		btSoftBody* psb = (btSoftBody*)m_softBodies[i];
		psb->defaultCollisionHandler(psb);
	}

[geo6]

Yes, these are the outer most functions. Then I traced through the code and found out that after those functions we go through broadphase bounding volume tree and end up doing vertex face collision detection in btSoftBodyInternals.h in this function:

struct CollideVF_SS : btDbvt::ICollide
{
void Process(const btDbvtNode* lnode,
const btDbvtNode* lface)

Just thought I would post this in case anyone else is also working on cloth to cloth collision

[steven]

Code: Select all

//only self-collision for Cluster, not Vertex-Face yet

from the comment, it seems that it only support self-collision for Cluster.
Could you try these interfaces to enable the cluster?

Code: Select all

pSoftBody->m_cfg.collisions = btSoftBody::fCollision::CL_SS | btSoftBody::fCollision::CL_RS | btSoftBody::fCollision::CL_SELF;;
btSoftBody::generateClusters(int k,int maxiterations)