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Fixes / improvements in soft body:

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avoid blow-up due to improper mass calculation for fixed nodes (happened when using clusters)
allow to create collision clusters for each tetrahedron or triangle, when using btSoftBody::generateClusters(0)
tweak soft body demos a bit, only draw debug wireframe if necessary
This commit is contained in:
erwin.coumans
2009-08-28 21:23:54 +00:00
parent f492899499
commit 2ef7c1a457
7 changed files with 218 additions and 68 deletions
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34
src/BulletSoftBody/btSoftBodyInternals.h
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@@ -19,6 +19,7 @@ subject to the following restrictions:
#include "btSoftBody.h"
#include "LinearMath/btQuickprof.h"
#include "BulletCollision/BroadphaseCollision/btBroadphaseInterface.h"
#include "BulletCollision/CollisionDispatch/btCollisionDispatcher.h"
@@ -654,14 +655,14 @@ struct btSoftColliders
{
btScalar erp;
btScalar idt;
btScalar margin;
btScalar m_margin;
btScalar friction;
btScalar threshold;
ClusterBase()
{
erp =(btScalar)1;
idt =0;
margin =0;
m_margin =0;
friction =0;
threshold =(btScalar)0;
}
@@ -669,16 +670,21 @@ struct btSoftColliders
btSoftBody::Body ba,btSoftBody::Body bb,
btSoftBody::CJoint& joint)
{
if(res.distance<margin)
if(res.distance<m_margin)
{
btVector3 norm = res.normal;
norm.normalize();//is it necessary?
const btVector3 ra=res.witnesses[0]-ba.xform().getOrigin();
const btVector3 rb=res.witnesses[1]-bb.xform().getOrigin();
const btVector3 va=ba.velocity(ra);
const btVector3 vb=bb.velocity(rb);
const btVector3 vrel=va-vb;
const btScalar rvac=btDot(vrel,res.normal);
const btScalar depth=res.distance-margin;
const btVector3 iv=res.normal*rvac;
const btScalar rvac=btDot(vrel,norm);
btScalar depth=res.distance-m_margin;
// printf("depth=%f\n",depth);
const btVector3 iv=norm*rvac;
const btVector3 fv=vrel-iv;
joint.m_bodies[0] = ba;
joint.m_bodies[1] = bb;
@@ -691,12 +697,16 @@ struct btSoftColliders
joint.m_life = 0;
joint.m_maxlife = 0;
joint.m_split = 1;
joint.m_drift = depth*res.normal;
joint.m_normal = res.normal;
joint.m_drift = depth*norm;
joint.m_normal = norm;
// printf("normal=%f,%f,%f\n",res.normal.getX(),res.normal.getY(),res.normal.getZ());
joint.m_delete = false;
joint.m_friction = fv.length2()<(-rvac*friction)?1:friction;
joint.m_massmatrix = ImpulseMatrix( ba.invMass(),ba.invWorldInertia(),joint.m_rpos[0],
bb.invMass(),bb.invWorldInertia(),joint.m_rpos[1]);
return(true);
}
return(false);
@@ -714,6 +724,7 @@ struct btSoftColliders
{
btSoftBody::Cluster* cluster=(btSoftBody::Cluster*)leaf->data;
btSoftClusterCollisionShape cshape(cluster);
const btConvexShape* rshape=(const btConvexShape*)m_colObj->getCollisionShape();
btGjkEpaSolver2::sResults res;
if(btGjkEpaSolver2::SignedDistance( &cshape,btTransform::getIdentity(),
@@ -743,7 +754,7 @@ struct btSoftColliders
psb = ps;
m_colObj = colOb;
idt = ps->m_sst.isdt;
margin = m_colObj->getCollisionShape()->getMargin();
m_margin = m_colObj->getCollisionShape()->getMargin()+psb->getCollisionShape()->getMargin();
///Bullet rigid body uses multiply instead of minimum to determine combined friction. Some customization would be useful.
friction = btMin(psb->m_cfg.kDF,m_colObj->getFriction());
btVector3 mins;
@@ -752,7 +763,7 @@ struct btSoftColliders
ATTRIBUTE_ALIGNED16(btDbvtVolume) volume;
colOb->getCollisionShape()->getAabb(colOb->getInterpolationWorldTransform(),mins,maxs);
volume=btDbvtVolume::FromMM(mins,maxs);
volume.Expand(btVector3(1,1,1)*margin);
volume.Expand(btVector3(1,1,1)*m_margin);
ps->m_cdbvt.collideTV(ps->m_cdbvt.m_root,volume,*this);
}
};
@@ -803,7 +814,8 @@ struct btSoftColliders
void Process(btSoftBody* psa,btSoftBody* psb)
{
idt = psa->m_sst.isdt;
margin = (psa->getCollisionShape()->getMargin()+psb->getCollisionShape()->getMargin())/2;
//m_margin = (psa->getCollisionShape()->getMargin()+psb->getCollisionShape()->getMargin())/2;
m_margin = (psa->getCollisionShape()->getMargin()+psb->getCollisionShape()->getMargin());
friction = btMin(psa->m_cfg.kDF,psb->m_cfg.kDF);
bodies[0] = psa;
bodies[1] = psb;