void
cpBodyUpdateVelocity(cpBody *body, cpVect gravity, cpFloat damping, cpFloat dt)
{
body->v = cpvclamp(cpvadd(cpvmult(body->v, damping), cpvmult(cpvadd(gravity, cpvmult(body->f, body->m_inv)), dt)), body->v_limit);
cpFloat w_limit = body->w_limit;
body->w = cpfclamp(body->w*damping + body->t*body->i_inv*dt, -w_limit, w_limit);
}
static void internalBodyUpdateVelocity(cpBody *body, cpVect gravity, cpFloat damping, cpFloat dt)
{
cpBodyUpdateVelocity(body, cpvzero, damping, dt);
// Skip kinematic bodies.
if(cpBodyGetType(body) == CP_BODY_TYPE_KINEMATIC) return;
cpAssertSoft(body->m > 0.0f && body->i > 0.0f, "Body's mass and moment must be positive to simulate. (Mass: %f Moment: f)", body->m, body->i);
cocos2d::PhysicsBody *physicsBody = static_cast<cocos2d::PhysicsBody*>(body->userData);
if(physicsBody->isGravityEnabled())
body->v = cpvclamp(cpvadd(cpvmult(body->v, damping), cpvmult(cpvadd(gravity, cpvmult(body->f, body->m_inv)), dt)), physicsBody->getVelocityLimit());
else
body->v = cpvclamp(cpvadd(cpvmult(body->v, damping), cpvmult(cpvmult(body->f, body->m_inv), dt)), physicsBody->getVelocityLimit());
cpFloat w_limit = physicsBody->getAngularVelocityLimit();
body->w = cpfclamp(body->w*damping + body->t*body->i_inv*dt, -w_limit, w_limit);
// Reset forces.
body->f = cpvzero;
//to check body sanity
cpBodySetTorque(body, 0.0f);
}
static void
preStep(cpPivotJoint *joint, cpFloat dt)
{
cpBody *a = joint->constraint.a;
cpBody *b = joint->constraint.b;
joint->r1 = cpTransformVect(a->transform, cpvsub(joint->anchorA, a->cog));
joint->r2 = cpTransformVect(b->transform, cpvsub(joint->anchorB, b->cog));
// Calculate mass tensor
joint-> k = k_tensor(a, b, joint->r1, joint->r2);
// calculate bias velocity
cpVect delta = cpvsub(cpvadd(b->p, joint->r2), cpvadd(a->p, joint->r1));
joint->bias = cpvclamp(cpvmult(delta, -bias_coef(joint->constraint.errorBias, dt)/dt), joint->constraint.maxBias);
}
static void
preStep(cpGrooveJoint *joint, cpFloat dt, cpFloat dt_inv)
{
cpBody *a = joint->constraint.a;
cpBody *b = joint->constraint.b;
// calculate endpoints in worldspace
cpVect ta = cpBodyLocal2World(a, joint->grv_a);
cpVect tb = cpBodyLocal2World(a, joint->grv_b);
// calculate axis
cpVect n = cpvrotate(joint->grv_n, a->rot);
cpFloat d = cpvdot(ta, n);
joint->grv_tn = n;
joint->r2 = cpvrotate(joint->anchr2, b->rot);
// calculate tangential distance along the axis of r2
cpFloat td = cpvcross(cpvadd(b->p, joint->r2), n);
// calculate clamping factor and r2
if(td <= cpvcross(ta, n)){
joint->clamp = 1.0f;
joint->r1 = cpvsub(ta, a->p);
} else if(td >= cpvcross(tb, n)){
joint->clamp = -1.0f;
joint->r1 = cpvsub(tb, a->p);
} else {
joint->clamp = 0.0f;
joint->r1 = cpvsub(cpvadd(cpvmult(cpvperp(n), -td), cpvmult(n, d)), a->p);
}
// Calculate mass tensor
k_tensor(a, b, joint->r1, joint->r2, &joint->k1, &joint->k2);
// compute max impulse
joint->jMaxLen = J_MAX(joint, dt);
// calculate bias velocity
cpVect delta = cpvsub(cpvadd(b->p, joint->r2), cpvadd(a->p, joint->r1));
joint->bias = cpvclamp(cpvmult(delta, -joint->constraint.biasCoef*dt_inv), joint->constraint.maxBias);
// apply accumulated impulse
apply_impulses(a, b, joint->r1, joint->r2, joint->jAcc);
}
static void
preStep(cpPivotJoint *joint, cpFloat dt)
{
cpBody *a = joint->constraint.a;
cpBody *b = joint->constraint.b;
joint->r1 = cpvrotate(joint->anchr1, a->rot);
joint->r2 = cpvrotate(joint->anchr2, b->rot);
// Calculate mass tensor
k_tensor(a, b, joint->r1, joint->r2, &joint->k1, &joint->k2);
// compute max impulse
joint->jMaxLen = J_MAX(joint, dt);
// calculate bias velocity
cpVect delta = cpvsub(cpvadd(b->p, joint->r2), cpvadd(a->p, joint->r1));
joint->bias = cpvclamp(cpvmult(delta, -bias_coef(joint->constraint.errorBias, dt)/dt), joint->constraint.maxBias);
}
static void
applyImpulse(cpPivotJoint *joint)
{
CONSTRAINT_BEGIN(joint, a, b);
cpVect r1 = joint->r1;
cpVect r2 = joint->r2;
// compute relative velocity
cpVect vr = relative_velocity(a, b, r1, r2);
// compute normal impulse
cpVect j = mult_k(cpvsub(joint->bias, vr), joint->k1, joint->k2);
cpVect jOld = joint->jAcc;
joint->jAcc = cpvclamp(cpvadd(joint->jAcc, j), joint->jMaxLen);
j = cpvsub(joint->jAcc, jOld);
// apply impulse
apply_impulses(a, b, joint->r1, joint->r2, j);
}
static void
applyImpulse(cpPivotJoint *joint, cpFloat dt)
{
cpBody *a = joint->constraint.a;
cpBody *b = joint->constraint.b;
cpVect r1 = joint->r1;
cpVect r2 = joint->r2;
// compute relative velocity
cpVect vr = relative_velocity(a, b, r1, r2);
// compute normal impulse
cpVect j = cpMat2x2Transform(joint->k, cpvsub(joint->bias, vr));
cpVect jOld = joint->jAcc;
joint->jAcc = cpvclamp(cpvadd(joint->jAcc, j), joint->constraint.maxForce*dt);
j = cpvsub(joint->jAcc, jOld);
// apply impulse
apply_impulses(a, b, joint->r1, joint->r2, j);
}
static void
preStep(cpPivotJoint *joint, cpFloat dt, cpFloat dt_inv)
{
CONSTRAINT_BEGIN(joint, a, b);
joint->r1 = cpvrotate(joint->anchr1, a->rot);
joint->r2 = cpvrotate(joint->anchr2, b->rot);
// Calculate mass tensor
k_tensor(a, b, joint->r1, joint->r2, &joint->k1, &joint->k2);
// compute max impulse
joint->jMaxLen = J_MAX(joint, dt);
// calculate bias velocity
cpVect delta = cpvsub(cpvadd(b->p, joint->r2), cpvadd(a->p, joint->r1));
joint->bias = cpvclamp(cpvmult(delta, -joint->constraint.biasCoef*dt_inv), joint->constraint.maxBias);
// apply accumulated impulse
apply_impulses(a, b, joint->r1, joint->r2, joint->jAcc);
}
static void
preStep(cpGrooveJoint *joint, cpFloat dt)
{
cpBody *a = joint->constraint.a;
cpBody *b = joint->constraint.b;
// calculate endpoints in worldspace
cpVect ta = cpTransformPoint(a->transform, joint->grv_a);
cpVect tb = cpTransformPoint(a->transform, joint->grv_b);
// calculate axis
cpVect n = cpTransformVect(a->transform, joint->grv_n);
cpFloat d = cpvdot(ta, n);
joint->grv_tn = n;
joint->r2 = cpTransformVect(b->transform, cpvsub(joint->anchorB, b->cog));
// calculate tangential distance along the axis of r2
cpFloat td = cpvcross(cpvadd(b->p, joint->r2), n);
// calculate clamping factor and r2
if(td <= cpvcross(ta, n)){
joint->clamp = 1.0f;
joint->r1 = cpvsub(ta, a->p);
} else if(td >= cpvcross(tb, n)){
joint->clamp = -1.0f;
joint->r1 = cpvsub(tb, a->p);
} else {
joint->clamp = 0.0f;
joint->r1 = cpvsub(cpvadd(cpvmult(cpvperp(n), -td), cpvmult(n, d)), a->p);
}
// Calculate mass tensor
joint->k = k_tensor(a, b, joint->r1, joint->r2);
// calculate bias velocity
cpVect delta = cpvsub(cpvadd(b->p, joint->r2), cpvadd(a->p, joint->r1));
joint->bias = cpvclamp(cpvmult(delta, -bias_coef(joint->constraint.errorBias, dt)/dt), joint->constraint.maxBias);
}
static inline cpVect
grooveConstrain(cpGrooveJoint *joint, cpVect j, cpFloat dt){
cpVect n = joint->grv_tn;
cpVect jClamp = (joint->clamp*cpvcross(j, n) > 0.0f) ? j : cpvproject(j, n);
return cpvclamp(jClamp, joint->constraint.maxForce*dt);
}
static inline cpVect
grooveConstrain(cpGrooveJoint *joint, cpVect j){
cpVect n = joint->grv_tn;
cpVect jClamp = (joint->clamp*cpvcross(j, n) > 0.0f) ? j : cpvproject(j, n);
return cpvclamp(jClamp, joint->jMaxLen);
}
