static void
preStep(cpPinJoint *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);
cpVect delta = cpvsub(cpvadd(b->p, joint->r2), cpvadd(a->p, joint->r1));
cpFloat dist = cpvlength(delta);
joint->n = cpvmult(delta, 1.0f/(dist ? dist : (cpFloat)INFINITY));
// calculate mass normal
joint->nMass = 1.0f/k_scalar(a, b, joint->r1, joint->r2, joint->n);
// calculate bias velocity
cpFloat maxBias = joint->constraint.maxBias;
joint->bias = cpfclamp(-joint->constraint.biasCoef*dt_inv*(dist - joint->dist), -maxBias, maxBias);
// compute max impulse
joint->jnMax = J_MAX(joint, dt);
// apply accumulated impulse
cpVect j = cpvmult(joint->n, joint->jnAcc);
apply_impulses(a, b, joint->r1, joint->r2, j);
}
static void
preStep(cpRotaryLimitJoint *joint, cpFloat dt, cpFloat dt_inv)
{
CONSTRAINT_BEGIN(joint, a, b);
cpFloat dist = b->a - a->a;
cpFloat pdist = 0.0f;
if(dist > joint->max) {
pdist = joint->max - dist;
} else if(dist < joint->min) {
pdist = joint->min - dist;
}
// calculate moment of inertia coefficient.
joint->iSum = 1.0f/(a->i_inv + b->i_inv);
// calculate bias velocity
cpFloat maxBias = joint->constraint.maxBias;
joint->bias = cpfclamp(-joint->constraint.biasCoef*dt_inv*(pdist), -maxBias, maxBias);
// compute max impulse
joint->jMax = J_MAX(joint, dt);
// If the bias is 0, the joint is not at a limit. Reset the impulse.
if(!joint->bias)
joint->jAcc = 0.0f;
// apply joint torque
a->w -= joint->jAcc*a->i_inv;
b->w += joint->jAcc*b->i_inv;
}
static void
preStep(cpSimpleMotor *joint, cpFloat dt, cpFloat dt_inv)
{
CONSTRAINT_BEGIN(joint, a, b);
// calculate moment of inertia coefficient.
joint->iSum = 1.0f/(a->i_inv + b->i_inv);
// compute max impulse
joint->jMax = J_MAX(joint, dt);
// apply joint torque
a->w -= joint->jAcc*a->i_inv;
b->w += joint->jAcc*b->i_inv;
}
static void
preStep(cpDampedRotarySpring *spring, cpFloat dt, cpFloat dt_inv)
{
CONSTRAINT_BEGIN(spring, a, b);
cpFloat moment = a->i_inv + b->i_inv;
spring->iSum = 1.0f/moment;
spring->w_coef = 1.0f - cpfexp(-spring->damping*dt*moment);
spring->target_wrn = 0.0f;
// apply spring torque
cpFloat j_spring = spring->springTorqueFunc((cpConstraint *)spring, a->a - b->a)*dt;
a->w -= j_spring*a->i_inv;
b->w += j_spring*b->i_inv;
}
static void
applyImpulse(cpGearJoint *joint)
{
CONSTRAINT_BEGIN(joint, a, b);
// compute relative rotational velocity
cpFloat wr = b->w*joint->ratio - a->w;
// compute normal impulse
cpFloat j = (joint->bias - wr)*joint->iSum;
cpFloat jOld = joint->jAcc;
joint->jAcc = cpfclamp(jOld + j, -joint->jMax, joint->jMax);
j = joint->jAcc - jOld;
// apply impulse
a->w -= j*a->i_inv*joint->ratio_inv;
b->w += j*b->i_inv;
}
static void
applyImpulse(cpPinJoint *joint)
{
CONSTRAINT_BEGIN(joint, a, b);
cpVect n = joint->n;
// compute relative velocity
cpFloat vrn = normal_relative_velocity(a, b, joint->r1, joint->r2, n);
// compute normal impulse
cpFloat jn = (joint->bias - vrn)*joint->nMass;
cpFloat jnOld = joint->jnAcc;
joint->jnAcc = cpfclamp(jnOld + jn, -joint->jnMax, joint->jnMax);
jn = joint->jnAcc - jnOld;
// apply impulse
apply_impulses(a, b, joint->r1, joint->r2, cpvmult(n, jn));
}
static void
applyImpulse(cpSimpleMotor *joint)
{
CONSTRAINT_BEGIN(joint, a, b);
// compute relative rotational velocity
cpFloat wr = b->w - a->w + joint->rate;
// compute normal impulse
cpFloat j = -wr*joint->iSum;
cpFloat jOld = joint->jAcc;
joint->jAcc = cpfclamp(jOld + j, -joint->jMax, joint->jMax);
j = joint->jAcc - jOld;
// apply impulse
a->w -= j*a->i_inv;
b->w += j*b->i_inv;
}
static void
applyImpulse(cpDampedRotarySpring *spring)
{
CONSTRAINT_BEGIN(spring, a, b);
// compute relative velocity
cpFloat wrn = a->w - b->w;//normal_relative_velocity(a, b, r1, r2, n) - spring->target_vrn;
// compute velocity loss from drag
// not 100% certain this is derived correctly, though it makes sense
cpFloat w_damp = wrn*spring->w_coef;
spring->target_wrn = wrn - w_damp;
//apply_impulses(a, b, spring->r1, spring->r2, cpvmult(spring->n, v_damp*spring->nMass));
cpFloat j_damp = w_damp*spring->iSum;
a->w -= j_damp*a->i_inv;
b->w += j_damp*b->i_inv;
}
static void
applyImpulse(cpGrooveJoint *joint)
{
CONSTRAINT_BEGIN(joint, a, b);
cpVect r1 = joint->r1;
cpVect r2 = joint->r2;
// compute impulse
cpVect vr = relative_velocity(a, b, r1, r2);
cpVect j = mult_k(cpvsub(joint->bias, vr), joint->k1, joint->k2);
cpVect jOld = joint->jAcc;
joint->jAcc = grooveConstrain(joint, cpvadd(jOld, j));
j = cpvsub(joint->jAcc, jOld);
// apply impulse
apply_impulses(a, b, joint->r1, joint->r2, j);
}
static void
preStep(cpGrooveJoint *joint, cpFloat dt, cpFloat dt_inv)
{
CONSTRAINT_BEGIN(joint, a, 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
applyImpulse(cpDampedSpring *spring)
{
CONSTRAINT_BEGIN(spring, a, b);
cpVect n = spring->n;
cpVect r1 = spring->r1;
cpVect r2 = spring->r2;
// compute relative velocity
cpFloat vrn = normal_relative_velocity(a, b, r1, r2, n) - spring->target_vrn;
// compute velocity loss from drag
// not 100% certain this is derived correctly, though it makes sense
cpFloat v_damp = -vrn*spring->v_coef;
spring->target_vrn = vrn + v_damp;
apply_impulses(a, b, spring->r1, spring->r2, cpvmult(spring->n, v_damp*spring->nMass));
}
static void
preStep(cpGearJoint *joint, cpFloat dt, cpFloat dt_inv)
{
CONSTRAINT_BEGIN(joint, a, b);
// calculate moment of inertia coefficient.
joint->iSum = 1.0f/(a->i_inv*joint->ratio_inv + joint->ratio*b->i_inv);
// calculate bias velocity
cpFloat maxBias = joint->constraint.maxBias;
joint->bias = cpfclamp(-joint->constraint.biasCoef*dt_inv*(b->a*joint->ratio - a->a - joint->phase), -maxBias, maxBias);
// compute max impulse
joint->jMax = J_MAX(joint, dt);
// apply joint torque
cpFloat j = joint->jAcc;
a->w -= j*a->i_inv*joint->ratio_inv;
b->w += j*b->i_inv;
}
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(cpRatchetJoint *joint)
{
if(!joint->bias) return; // early exit
CONSTRAINT_BEGIN(joint, a, b);
// compute relative rotational velocity
cpFloat wr = b->w - a->w;
cpFloat ratchet = joint->ratchet;
// compute normal impulse
cpFloat j = -(joint->bias + wr)*joint->iSum;
cpFloat jOld = joint->jAcc;
joint->jAcc = cpfclamp((jOld + j)*ratchet, 0.0f, joint->jMax*cpfabs(ratchet))/ratchet;
j = joint->jAcc - jOld;
// apply impulse
a->w -= j*a->i_inv;
b->w += j*b->i_inv;
}
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(cpDampedSpring *spring, cpFloat dt, cpFloat dt_inv)
{
CONSTRAINT_BEGIN(spring, a, b);
spring->r1 = cpvrotate(spring->anchr1, a->rot);
spring->r2 = cpvrotate(spring->anchr2, b->rot);
cpVect delta = cpvsub(cpvadd(b->p, spring->r2), cpvadd(a->p, spring->r1));
cpFloat dist = cpvlength(delta);
spring->n = cpvmult(delta, 1.0f/(dist ? dist : INFINITY));
cpFloat k = k_scalar(a, b, spring->r1, spring->r2, spring->n);
spring->nMass = 1.0f/k;
spring->target_vrn = 0.0f;
spring->v_coef = 1.0f - cpfexp(-spring->damping*dt*k);
// apply spring force
cpFloat f_spring = spring->springForceFunc((cpConstraint *)spring, dist);
apply_impulses(a, b, spring->r1, spring->r2, cpvmult(spring->n, f_spring*dt));
}
static void
preStep(cpSlideJoint *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);
cpVect delta = cpvsub(cpvadd(b->p, joint->r2), cpvadd(a->p, joint->r1));
cpFloat dist = cpvlength(delta);
cpFloat pdist = 0.0f;
if(dist > joint->max) {
pdist = dist - joint->max;
} else if(dist < joint->min) {
pdist = joint->min - dist;
dist = -dist;
}
joint->n = cpvmult(delta, 1.0f/(dist ? dist : (cpFloat)CP_INFINITY));
// calculate mass normal
joint->nMass = 1.0f/k_scalar(a, b, joint->r1, joint->r2, joint->n);
// calculate bias velocity
cpFloat maxBias = joint->constraint.maxBias;
joint->bias = cpfclamp(-joint->constraint.biasCoef*dt_inv*(pdist), -maxBias, maxBias);
// compute max impulse
joint->jnMax = J_MAX(joint, dt);
// apply accumulated impulse
if(!joint->bias) //{
// if bias is 0, then the joint is not at a limit.
joint->jnAcc = 0.0f;
// } else {
cpVect j = cpvmult(joint->n, joint->jnAcc);
apply_impulses(a, b, joint->r1, joint->r2, j);
// }
}
static void
preStep(cpRatchetJoint *joint, cpFloat dt, cpFloat dt_inv)
{
CONSTRAINT_BEGIN(joint, a, b);
cpFloat angle = joint->angle;
cpFloat phase = joint->phase;
cpFloat ratchet = joint->ratchet;
cpFloat delta = b->a - a->a;
cpFloat diff = angle - delta;
cpFloat pdist = 0.0f;
if(diff*ratchet > 0.0f){
pdist = diff;
} else {
joint->angle = cpffloor((delta - phase)/ratchet)*ratchet + phase;
}
// calculate moment of inertia coefficient.
joint->iSum = 1.0f/(a->i_inv + b->i_inv);
// calculate bias velocity
cpFloat maxBias = joint->constraint.maxBias;
joint->bias = cpfclamp(-joint->constraint.biasCoef*dt_inv*pdist, -maxBias, maxBias);
// compute max impulse
joint->jMax = J_MAX(joint, dt);
// If the bias is 0, the joint is not at a limit. Reset the impulse.
if(!joint->bias)
joint->jAcc = 0.0f;
// apply joint torque
a->w -= joint->jAcc*a->i_inv;
b->w += joint->jAcc*b->i_inv;
}
static void
applyImpulse(cpRotaryLimitJoint *joint)
{
if(!joint->bias) return; // early exit
CONSTRAINT_BEGIN(joint, a, b);
// compute relative rotational velocity
cpFloat wr = b->w - a->w;
// compute normal impulse
cpFloat j = -(joint->bias + wr)*joint->iSum;
cpFloat jOld = joint->jAcc;
if(joint->bias < 0.0f){
joint->jAcc = cpfclamp(jOld + j, 0.0f, joint->jMax);
} else {
joint->jAcc = cpfclamp(jOld + j, -joint->jMax, 0.0f);
}
j = joint->jAcc - jOld;
// apply impulse
a->w -= j*a->i_inv;
b->w += j*b->i_inv;
}
static void
applyImpulse(cpSlideJoint *joint)
{
if(!joint->bias) return; // early exit
CONSTRAINT_BEGIN(joint, a, b);
cpVect n = joint->n;
cpVect r1 = joint->r1;
cpVect r2 = joint->r2;
// compute relative velocity
cpVect vr = relative_velocity(a, b, r1, r2);
cpFloat vrn = cpvdot(vr, n);
// compute normal impulse
cpFloat jn = (joint->bias - vrn)*joint->nMass;
cpFloat jnOld = joint->jnAcc;
joint->jnAcc = cpfclamp(jnOld + jn, -joint->jnMax, 0.0f);
jn = joint->jnAcc - jnOld;
// apply impulse
apply_impulses(a, b, joint->r1, joint->r2, cpvmult(n, jn));
}