/*
* Java port of Bullet (c) 2008 Martin Dvorak <jezek2@advel.cz>
*
* Bullet Continuous Collision Detection and Physics Library
* Copyright (c) 2003-2008 Erwin Coumans http://www.bulletphysics.com/
*
* This software is provided 'as-is', without any express or implied warranty.
* In no event will the authors be held liable for any damages arising from
* the use of this software.
*
* Permission is granted to anyone to use this software for any purpose,
* including commercial applications, and to alter it and redistribute it
* freely, subject to the following restrictions:
*
* 1. The origin of this software must not be misrepresented; you must not
* claim that you wrote the original software. If you use this software
* in a product, an acknowledgment in the product documentation would be
* appreciated but is not required.
* 2. Altered source versions must be plainly marked as such, and must not be
* misrepresented as being the original software.
* 3. This notice may not be removed or altered from any source distribution.
*/
package com.bulletphysics.dynamics.constraintsolver;
import com.bulletphysics.BulletGlobals;
import com.bulletphysics.util.ObjectPool;
import com.bulletphysics.collision.narrowphase.ManifoldPoint;
import com.bulletphysics.dynamics.RigidBody;
import com.bulletphysics.linearmath.Transform;
import cz.advel.stack.Stack;
import javax.vecmath.Matrix3f;
import javax.vecmath.Vector3f;
/**
* Functions for resolving contacts.
*
* @author jezek2
*/
public class ContactConstraint {
public static final ContactSolverFunc resolveSingleCollision = new ContactSolverFunc() {
public float resolveContact(RigidBody body1, RigidBody body2, ManifoldPoint contactPoint, ContactSolverInfo info) {
return resolveSingleCollision(body1, body2, contactPoint, info);
}
};
public static final ContactSolverFunc resolveSingleFriction = new ContactSolverFunc() {
public float resolveContact(RigidBody body1, RigidBody body2, ManifoldPoint contactPoint, ContactSolverInfo info) {
return resolveSingleFriction(body1, body2, contactPoint, info);
}
};
public static final ContactSolverFunc resolveSingleCollisionCombined = new ContactSolverFunc() {
public float resolveContact(RigidBody body1, RigidBody body2, ManifoldPoint contactPoint, ContactSolverInfo info) {
return resolveSingleCollisionCombined(body1, body2, contactPoint, info);
}
};
/**
* Bilateral constraint between two dynamic objects.
*/
public static void resolveSingleBilateral(RigidBody body1, Vector3f pos1,
RigidBody body2, Vector3f pos2,
float distance, Vector3f normal, float[] impulse, float timeStep) {
float normalLenSqr = normal.lengthSquared();
assert (Math.abs(normalLenSqr) < 1.1f);
if (normalLenSqr > 1.1f) {
impulse[0] = 0f;
return;
}
ObjectPool<JacobianEntry> jacobiansPool = ObjectPool.get(JacobianEntry.class);
Vector3f tmp = Stack.alloc(Vector3f.class);
Vector3f rel_pos1 = Stack.alloc(Vector3f.class);
rel_pos1.sub(pos1, body1.getCenterOfMassPosition(tmp));
Vector3f rel_pos2 = Stack.alloc(Vector3f.class);
rel_pos2.sub(pos2, body2.getCenterOfMassPosition(tmp));
//this jacobian entry could be re-used for all iterations
Vector3f vel1 = Stack.alloc(Vector3f.class);
body1.getVelocityInLocalPoint(rel_pos1, vel1);
Vector3f vel2 = Stack.alloc(Vector3f.class);
body2.getVelocityInLocalPoint(rel_pos2, vel2);
Vector3f vel = Stack.alloc(Vector3f.class);
vel.sub(vel1, vel2);
Matrix3f mat1 = body1.getCenterOfMassTransform(Stack.alloc(Transform.class)).basis;
mat1.transpose();
Matrix3f mat2 = body2.getCenterOfMassTransform(Stack.alloc(Transform.class)).basis;
mat2.transpose();
JacobianEntry jac = jacobiansPool.get();
jac.init(mat1, mat2,
rel_pos1, rel_pos2, normal,
body1.getInvInertiaDiagLocal(Stack.alloc(Vector3f.class)), body1.getInvMass(),
body2.getInvInertiaDiagLocal(Stack.alloc(Vector3f.class)), body2.getInvMass());
float jacDiagAB = jac.getDiagonal();
float jacDiagABInv = 1f / jacDiagAB;
Vector3f tmp1 = body1.getAngularVelocity(Stack.alloc(Vector3f.class));
mat1.transform(tmp1);
Vector3f tmp2 = body2.getAngularVelocity(Stack.alloc(Vector3f.class));
mat2.transform(tmp2);
float rel_vel = jac.getRelativeVelocity(
body1.getLinearVelocity(Stack.alloc(Vector3f.class)),
tmp1,
body2.getLinearVelocity(Stack.alloc(Vector3f.class)),
tmp2);
jacobiansPool.release(jac);
float a;
a = jacDiagABInv;
rel_vel = normal.dot(vel);
// todo: move this into proper structure
float contactDamping = 0.2f;
//#ifdef ONLY_USE_LINEAR_MASS
// btScalar massTerm = btScalar(1.) / (body1.getInvMass() + body2.getInvMass());
// impulse = - contactDamping * rel_vel * massTerm;
//#else
float velocityImpulse = -contactDamping * rel_vel * jacDiagABInv;
impulse[0] = velocityImpulse;
//#endif
}
/**
* Response between two dynamic objects with friction.
*/
public static float resolveSingleCollision(
RigidBody body1,
RigidBody body2,
ManifoldPoint contactPoint,
ContactSolverInfo solverInfo) {
Vector3f tmpVec = Stack.alloc(Vector3f.class);
Vector3f pos1_ = contactPoint.getPositionWorldOnA(Stack.alloc(Vector3f.class));
Vector3f pos2_ = contactPoint.getPositionWorldOnB(Stack.alloc(Vector3f.class));
Vector3f normal = contactPoint.normalWorldOnB;
// constant over all iterations
Vector3f rel_pos1 = Stack.alloc(Vector3f.class);
rel_pos1.sub(pos1_, body1.getCenterOfMassPosition(tmpVec));
Vector3f rel_pos2 = Stack.alloc(Vector3f.class);
rel_pos2.sub(pos2_, body2.getCenterOfMassPosition(tmpVec));
Vector3f vel1 = body1.getVelocityInLocalPoint(rel_pos1, Stack.alloc(Vector3f.class));
Vector3f vel2 = body2.getVelocityInLocalPoint(rel_pos2, Stack.alloc(Vector3f.class));
Vector3f vel = Stack.alloc(Vector3f.class);
vel.sub(vel1, vel2);
float rel_vel;
rel_vel = normal.dot(vel);
float Kfps = 1f / solverInfo.timeStep;
// btScalar damping = solverInfo.m_damping ;
float Kerp = solverInfo.erp;
float Kcor = Kerp * Kfps;
ConstraintPersistentData cpd = (ConstraintPersistentData) contactPoint.userPersistentData;
assert (cpd != null);
float distance = cpd.penetration;
float positionalError = Kcor * -distance;
float velocityError = cpd.restitution - rel_vel; // * damping;
float penetrationImpulse = positionalError * cpd.jacDiagABInv;
float velocityImpulse = velocityError * cpd.jacDiagABInv;
float normalImpulse = penetrationImpulse + velocityImpulse;
// See Erin Catto's GDC 2006 paper: Clamp the accumulated impulse
float oldNormalImpulse = cpd.appliedImpulse;
float sum = oldNormalImpulse + normalImpulse;
cpd.appliedImpulse = 0f > sum ? 0f : sum;
normalImpulse = cpd.appliedImpulse - oldNormalImpulse;
//#ifdef USE_INTERNAL_APPLY_IMPULSE
Vector3f tmp = Stack.alloc(Vector3f.class);
if (body1.getInvMass() != 0f) {
tmp.scale(body1.getInvMass(), contactPoint.normalWorldOnB);
body1.internalApplyImpulse(tmp, cpd.angularComponentA, normalImpulse);
}
if (body2.getInvMass() != 0f) {
tmp.scale(body2.getInvMass(), contactPoint.normalWorldOnB);
body2.internalApplyImpulse(tmp, cpd.angularComponentB, -normalImpulse);
}
//#else //USE_INTERNAL_APPLY_IMPULSE
// body1.applyImpulse(normal*(normalImpulse), rel_pos1);
// body2.applyImpulse(-normal*(normalImpulse), rel_pos2);
//#endif //USE_INTERNAL_APPLY_IMPULSE
return normalImpulse;
}
public static float resolveSingleFriction(
RigidBody body1,
RigidBody body2,
ManifoldPoint contactPoint,
ContactSolverInfo solverInfo) {
Vector3f tmpVec = Stack.alloc(Vector3f.class);
Vector3f pos1 = contactPoint.getPositionWorldOnA(Stack.alloc(Vector3f.class));
Vector3f pos2 = contactPoint.getPositionWorldOnB(Stack.alloc(Vector3f.class));
Vector3f rel_pos1 = Stack.alloc(Vector3f.class);
rel_pos1.sub(pos1, body1.getCenterOfMassPosition(tmpVec));
Vector3f rel_pos2 = Stack.alloc(Vector3f.class);
rel_pos2.sub(pos2, body2.getCenterOfMassPosition(tmpVec));
ConstraintPersistentData cpd = (ConstraintPersistentData) contactPoint.userPersistentData;
assert (cpd != null);
float combinedFriction = cpd.friction;
float limit = cpd.appliedImpulse * combinedFriction;
if (cpd.appliedImpulse > 0f) //friction
{
//apply friction in the 2 tangential directions
// 1st tangent
Vector3f vel1 = Stack.alloc(Vector3f.class);
body1.getVelocityInLocalPoint(rel_pos1, vel1);
Vector3f vel2 = Stack.alloc(Vector3f.class);
body2.getVelocityInLocalPoint(rel_pos2, vel2);
Vector3f vel = Stack.alloc(Vector3f.class);
vel.sub(vel1, vel2);
float j1, j2;
{
float vrel = cpd.frictionWorldTangential0.dot(vel);
// calculate j that moves us to zero relative velocity
j1 = -vrel * cpd.jacDiagABInvTangent0;
float oldTangentImpulse = cpd.accumulatedTangentImpulse0;
cpd.accumulatedTangentImpulse0 = oldTangentImpulse + j1;
cpd.accumulatedTangentImpulse0 = Math.min(cpd.accumulatedTangentImpulse0, limit);
cpd.accumulatedTangentImpulse0 = Math.max(cpd.accumulatedTangentImpulse0, -limit);
j1 = cpd.accumulatedTangentImpulse0 - oldTangentImpulse;
}
{
// 2nd tangent
float vrel = cpd.frictionWorldTangential1.dot(vel);
// calculate j that moves us to zero relative velocity
j2 = -vrel * cpd.jacDiagABInvTangent1;
float oldTangentImpulse = cpd.accumulatedTangentImpulse1;
cpd.accumulatedTangentImpulse1 = oldTangentImpulse + j2;
cpd.accumulatedTangentImpulse1 = Math.min(cpd.accumulatedTangentImpulse1, limit);
cpd.accumulatedTangentImpulse1 = Math.max(cpd.accumulatedTangentImpulse1, -limit);
j2 = cpd.accumulatedTangentImpulse1 - oldTangentImpulse;
}
//#ifdef USE_INTERNAL_APPLY_IMPULSE
Vector3f tmp = Stack.alloc(Vector3f.class);
if (body1.getInvMass() != 0f) {
tmp.scale(body1.getInvMass(), cpd.frictionWorldTangential0);
body1.internalApplyImpulse(tmp, cpd.frictionAngularComponent0A, j1);
tmp.scale(body1.getInvMass(), cpd.frictionWorldTangential1);
body1.internalApplyImpulse(tmp, cpd.frictionAngularComponent1A, j2);
}
if (body2.getInvMass() != 0f) {
tmp.scale(body2.getInvMass(), cpd.frictionWorldTangential0);
body2.internalApplyImpulse(tmp, cpd.frictionAngularComponent0B, -j1);
tmp.scale(body2.getInvMass(), cpd.frictionWorldTangential1);
body2.internalApplyImpulse(tmp, cpd.frictionAngularComponent1B, -j2);
}
//#else //USE_INTERNAL_APPLY_IMPULSE
// body1.applyImpulse((j1 * cpd->m_frictionWorldTangential0)+(j2 * cpd->m_frictionWorldTangential1), rel_pos1);
// body2.applyImpulse((j1 * -cpd->m_frictionWorldTangential0)+(j2 * -cpd->m_frictionWorldTangential1), rel_pos2);
//#endif //USE_INTERNAL_APPLY_IMPULSE
}
return cpd.appliedImpulse;
}
/**
* velocity + friction<br>
* response between two dynamic objects with friction
*/
public static float resolveSingleCollisionCombined(
RigidBody body1,
RigidBody body2,
ManifoldPoint contactPoint,
ContactSolverInfo solverInfo) {
Vector3f tmpVec = Stack.alloc(Vector3f.class);
Vector3f pos1 = contactPoint.getPositionWorldOnA(Stack.alloc(Vector3f.class));
Vector3f pos2 = contactPoint.getPositionWorldOnB(Stack.alloc(Vector3f.class));
Vector3f normal = contactPoint.normalWorldOnB;
Vector3f rel_pos1 = Stack.alloc(Vector3f.class);
rel_pos1.sub(pos1, body1.getCenterOfMassPosition(tmpVec));
Vector3f rel_pos2 = Stack.alloc(Vector3f.class);
rel_pos2.sub(pos2, body2.getCenterOfMassPosition(tmpVec));
Vector3f vel1 = body1.getVelocityInLocalPoint(rel_pos1, Stack.alloc(Vector3f.class));
Vector3f vel2 = body2.getVelocityInLocalPoint(rel_pos2, Stack.alloc(Vector3f.class));
Vector3f vel = Stack.alloc(Vector3f.class);
vel.sub(vel1, vel2);
float rel_vel;
rel_vel = normal.dot(vel);
float Kfps = 1f / solverInfo.timeStep;
//btScalar damping = solverInfo.m_damping ;
float Kerp = solverInfo.erp;
float Kcor = Kerp * Kfps;
ConstraintPersistentData cpd = (ConstraintPersistentData) contactPoint.userPersistentData;
assert (cpd != null);
float distance = cpd.penetration;
float positionalError = Kcor * -distance;
float velocityError = cpd.restitution - rel_vel;// * damping;
float penetrationImpulse = positionalError * cpd.jacDiagABInv;
float velocityImpulse = velocityError * cpd.jacDiagABInv;
float normalImpulse = penetrationImpulse + velocityImpulse;
// See Erin Catto's GDC 2006 paper: Clamp the accumulated impulse
float oldNormalImpulse = cpd.appliedImpulse;
float sum = oldNormalImpulse + normalImpulse;
cpd.appliedImpulse = 0f > sum ? 0f : sum;
normalImpulse = cpd.appliedImpulse - oldNormalImpulse;
//#ifdef USE_INTERNAL_APPLY_IMPULSE
Vector3f tmp = Stack.alloc(Vector3f.class);
if (body1.getInvMass() != 0f) {
tmp.scale(body1.getInvMass(), contactPoint.normalWorldOnB);
body1.internalApplyImpulse(tmp, cpd.angularComponentA, normalImpulse);
}
if (body2.getInvMass() != 0f) {
tmp.scale(body2.getInvMass(), contactPoint.normalWorldOnB);
body2.internalApplyImpulse(tmp, cpd.angularComponentB, -normalImpulse);
}
//#else //USE_INTERNAL_APPLY_IMPULSE
// body1.applyImpulse(normal*(normalImpulse), rel_pos1);
// body2.applyImpulse(-normal*(normalImpulse), rel_pos2);
//#endif //USE_INTERNAL_APPLY_IMPULSE
{
//friction
body1.getVelocityInLocalPoint(rel_pos1, vel1);
body2.getVelocityInLocalPoint(rel_pos2, vel2);
vel.sub(vel1, vel2);
rel_vel = normal.dot(vel);
tmp.scale(rel_vel, normal);
Vector3f lat_vel = Stack.alloc(Vector3f.class);
lat_vel.sub(vel, tmp);
float lat_rel_vel = lat_vel.length();
float combinedFriction = cpd.friction;
if (cpd.appliedImpulse > 0) {
if (lat_rel_vel > BulletGlobals.FLT_EPSILON) {
lat_vel.scale(1f / lat_rel_vel);
Vector3f temp1 = Stack.alloc(Vector3f.class);
temp1.cross(rel_pos1, lat_vel);
body1.getInvInertiaTensorWorld(Stack.alloc(Matrix3f.class)).transform(temp1);
Vector3f temp2 = Stack.alloc(Vector3f.class);
temp2.cross(rel_pos2, lat_vel);
body2.getInvInertiaTensorWorld(Stack.alloc(Matrix3f.class)).transform(temp2);
Vector3f java_tmp1 = Stack.alloc(Vector3f.class);
java_tmp1.cross(temp1, rel_pos1);
Vector3f java_tmp2 = Stack.alloc(Vector3f.class);
java_tmp2.cross(temp2, rel_pos2);
tmp.add(java_tmp1, java_tmp2);
float friction_impulse = lat_rel_vel /
(body1.getInvMass() + body2.getInvMass() + lat_vel.dot(tmp));
float normal_impulse = cpd.appliedImpulse * combinedFriction;
friction_impulse = Math.min(friction_impulse, normal_impulse);
friction_impulse = Math.max(friction_impulse, -normal_impulse);
tmp.scale(-friction_impulse, lat_vel);
body1.applyImpulse(tmp, rel_pos1);
tmp.scale(friction_impulse, lat_vel);
body2.applyImpulse(tmp, rel_pos2);
}
}
}
return normalImpulse;
}
public static float resolveSingleFrictionEmpty(
RigidBody body1,
RigidBody body2,
ManifoldPoint contactPoint,
ContactSolverInfo solverInfo) {
return 0f;
}
}