@Override
public boolean solvePositionConstraints(final org.jbox2d.dynamics.SolverData data) {
final Rot qA = pool.popRot();
final Rot qB = pool.popRot();
Vec2 cA = data.positions[m_indexA].c;
float aA = data.positions[m_indexA].a;
Vec2 cB = data.positions[m_indexB].c;
float aB = data.positions[m_indexB].a;
qA.set(aA);
qB.set(aB);
float angularError = 0.0f;
float positionError = 0.0f;
boolean fixedRotation = (m_invIA + m_invIB == 0.0f);
// Solve angular limit constraint.
if (m_enableLimit && m_limitState != LimitState.INACTIVE && fixedRotation == false) {
float angle = aB - aA - m_referenceAngle;
float limitImpulse = 0.0f;
if (m_limitState == LimitState.EQUAL) {
// Prevent large angular corrections
float C =
MathUtils.clamp(
angle - m_lowerAngle,
-Settings.maxAngularCorrection,
Settings.maxAngularCorrection);
limitImpulse = -m_motorMass * C;
angularError = MathUtils.abs(C);
} else if (m_limitState == LimitState.AT_LOWER) {
float C = angle - m_lowerAngle;
angularError = -C;
// Prevent large angular corrections and allow some slop.
C = MathUtils.clamp(C + Settings.angularSlop, -Settings.maxAngularCorrection, 0.0f);
limitImpulse = -m_motorMass * C;
} else if (m_limitState == LimitState.AT_UPPER) {
float C = angle - m_upperAngle;
angularError = C;
// Prevent large angular corrections and allow some slop.
C = MathUtils.clamp(C - Settings.angularSlop, 0.0f, Settings.maxAngularCorrection);
limitImpulse = -m_motorMass * C;
}
aA -= m_invIA * limitImpulse;
aB += m_invIB * limitImpulse;
}
// Solve point-to-point constraint.
{
qA.set(aA);
qB.set(aB);
final Vec2 rA = pool.popVec2();
final Vec2 rB = pool.popVec2();
final Vec2 C = pool.popVec2();
final Vec2 impulse = pool.popVec2();
Rot.mulToOutUnsafe(qA, C.set(m_localAnchorA).subLocal(m_localCenterA), rA);
Rot.mulToOutUnsafe(qB, C.set(m_localAnchorB).subLocal(m_localCenterB), rB);
C.set(cB).addLocal(rB).subLocal(cA).subLocal(rA);
positionError = C.length();
float mA = m_invMassA, mB = m_invMassB;
float iA = m_invIA, iB = m_invIB;
final org.jbox2d.common.Mat22 K = pool.popMat22();
K.ex.x = mA + mB + iA * rA.y * rA.y + iB * rB.y * rB.y;
K.ex.y = -iA * rA.x * rA.y - iB * rB.x * rB.y;
K.ey.x = K.ex.y;
K.ey.y = mA + mB + iA * rA.x * rA.x + iB * rB.x * rB.x;
K.solveToOut(C, impulse);
impulse.negateLocal();
cA.x -= mA * impulse.x;
cA.y -= mA * impulse.y;
aA -= iA * Vec2.cross(rA, impulse);
cB.x += mB * impulse.x;
cB.y += mB * impulse.y;
aB += iB * Vec2.cross(rB, impulse);
pool.pushVec2(4);
pool.pushMat22(1);
}
// data.positions[m_indexA].c.set(cA);
data.positions[m_indexA].a = aA;
// data.positions[m_indexB].c.set(cB);
data.positions[m_indexB].a = aB;
pool.pushRot(2);
return positionError <= Settings.linearSlop && angularError <= Settings.angularSlop;
}
@Override
public final boolean raycast(
RayCastOutput output, RayCastInput input, Transform xf, int childIndex) {
final Vec2 p1 = pool1;
final Vec2 p2 = pool2;
final Vec2 d = pool3;
final Vec2 temp = pool4;
p1.set(input.p1).subLocal(xf.p);
Rot.mulTrans(xf.q, p1, p1);
p2.set(input.p2).subLocal(xf.p);
Rot.mulTrans(xf.q, p2, p2);
d.set(p2).subLocal(p1);
// if (count == 2) {
// } else {
float lower = 0, upper = input.maxFraction;
int index = -1;
for (int i = 0; i < m_count; ++i) {
// p = p1 + a * d
// dot(normal, p - v) = 0
// dot(normal, p1 - v) + a * dot(normal, d) = 0
temp.set(m_vertices[i]).subLocal(p1);
final float numerator = Vec2.dot(m_normals[i], temp);
final float denominator = Vec2.dot(m_normals[i], d);
if (denominator == 0.0f) {
if (numerator < 0.0f) {
return false;
}
} else {
// Note: we want this predicate without division:
// lower < numerator / denominator, where denominator < 0
// Since denominator < 0, we have to flip the inequality:
// lower < numerator / denominator <==> denominator * lower >
// numerator.
if (denominator < 0.0f && numerator < lower * denominator) {
// Increase lower.
// The segment enters this half-space.
lower = numerator / denominator;
index = i;
} else if (denominator > 0.0f && numerator < upper * denominator) {
// Decrease upper.
// The segment exits this half-space.
upper = numerator / denominator;
}
}
if (upper < lower) {
return false;
}
}
assert (0.0f <= lower && lower <= input.maxFraction);
if (index >= 0) {
output.fraction = lower;
Rot.mulToOutUnsafe(xf.q, m_normals[index], output.normal);
// normal = Mul(xf.R, m_normals[index]);
return true;
}
return false;
}
@Override
public void initVelocityConstraints(final org.jbox2d.dynamics.SolverData data) {
m_indexA = m_bodyA.m_islandIndex;
m_indexB = m_bodyB.m_islandIndex;
m_localCenterA.set(m_bodyA.m_sweep.localCenter);
m_localCenterB.set(m_bodyB.m_sweep.localCenter);
m_invMassA = m_bodyA.m_invMass;
m_invMassB = m_bodyB.m_invMass;
m_invIA = m_bodyA.m_invI;
m_invIB = m_bodyB.m_invI;
// Vec2 cA = data.positions[m_indexA].c;
float aA = data.positions[m_indexA].a;
Vec2 vA = data.velocities[m_indexA].v;
float wA = data.velocities[m_indexA].w;
// Vec2 cB = data.positions[m_indexB].c;
float aB = data.positions[m_indexB].a;
Vec2 vB = data.velocities[m_indexB].v;
float wB = data.velocities[m_indexB].w;
final Rot qA = pool.popRot();
final Rot qB = pool.popRot();
final Vec2 temp = pool.popVec2();
qA.set(aA);
qB.set(aB);
// Compute the effective masses.
Rot.mulToOutUnsafe(qA, temp.set(m_localAnchorA).subLocal(m_localCenterA), m_rA);
Rot.mulToOutUnsafe(qB, temp.set(m_localAnchorB).subLocal(m_localCenterB), m_rB);
// J = [-I -r1_skew I r2_skew]
// [ 0 -1 0 1]
// r_skew = [-ry; rx]
// Matlab
// K = [ mA+r1y^2*iA+mB+r2y^2*iB, -r1y*iA*r1x-r2y*iB*r2x, -r1y*iA-r2y*iB]
// [ -r1y*iA*r1x-r2y*iB*r2x, mA+r1x^2*iA+mB+r2x^2*iB, r1x*iA+r2x*iB]
// [ -r1y*iA-r2y*iB, r1x*iA+r2x*iB, iA+iB]
float mA = m_invMassA, mB = m_invMassB;
float iA = m_invIA, iB = m_invIB;
boolean fixedRotation = (iA + iB == 0.0f);
m_mass.ex.x = mA + mB + m_rA.y * m_rA.y * iA + m_rB.y * m_rB.y * iB;
m_mass.ey.x = -m_rA.y * m_rA.x * iA - m_rB.y * m_rB.x * iB;
m_mass.ez.x = -m_rA.y * iA - m_rB.y * iB;
m_mass.ex.y = m_mass.ey.x;
m_mass.ey.y = mA + mB + m_rA.x * m_rA.x * iA + m_rB.x * m_rB.x * iB;
m_mass.ez.y = m_rA.x * iA + m_rB.x * iB;
m_mass.ex.z = m_mass.ez.x;
m_mass.ey.z = m_mass.ez.y;
m_mass.ez.z = iA + iB;
m_motorMass = iA + iB;
if (m_motorMass > 0.0f) {
m_motorMass = 1.0f / m_motorMass;
}
if (m_enableMotor == false || fixedRotation) {
m_motorImpulse = 0.0f;
}
if (m_enableLimit && fixedRotation == false) {
float jointAngle = aB - aA - m_referenceAngle;
if (MathUtils.abs(m_upperAngle - m_lowerAngle) < 2.0f * Settings.angularSlop) {
m_limitState = LimitState.EQUAL;
} else if (jointAngle <= m_lowerAngle) {
if (m_limitState != LimitState.AT_LOWER) {
m_impulse.z = 0.0f;
}
m_limitState = LimitState.AT_LOWER;
} else if (jointAngle >= m_upperAngle) {
if (m_limitState != LimitState.AT_UPPER) {
m_impulse.z = 0.0f;
}
m_limitState = LimitState.AT_UPPER;
} else {
m_limitState = LimitState.INACTIVE;
m_impulse.z = 0.0f;
}
} else {
m_limitState = LimitState.INACTIVE;
}
if (data.step.warmStarting) {
final Vec2 P = pool.popVec2();
// Scale impulses to support a variable time step.
m_impulse.x *= data.step.dtRatio;
m_impulse.y *= data.step.dtRatio;
m_motorImpulse *= data.step.dtRatio;
P.x = m_impulse.x;
P.y = m_impulse.y;
vA.x -= mA * P.x;
vA.y -= mA * P.y;
wA -= iA * (Vec2.cross(m_rA, P) + m_motorImpulse + m_impulse.z);
vB.x += mB * P.x;
vB.y += mB * P.y;
wB += iB * (Vec2.cross(m_rB, P) + m_motorImpulse + m_impulse.z);
pool.pushVec2(1);
} else {
m_impulse.setZero();
m_motorImpulse = 0.0f;
}
// data.velocities[m_indexA].v.set(vA);
data.velocities[m_indexA].w = wA;
// data.velocities[m_indexB].v.set(vB);
data.velocities[m_indexB].w = wB;
pool.pushVec2(1);
pool.pushRot(2);
}