public override bool SolvePositionConstraints(b2SolverData data)
{
b2Vec2 cA = data.positions[m_indexA].c;
float aA = data.positions[m_indexA].a;
b2Vec2 cB = data.positions[m_indexB].c;
float aB = data.positions[m_indexB].a;
b2Rot qA = new b2Rot(aA);
b2Rot qB = new b2Rot(aB);
float angularError = 0.0f;
float positionError = 0.0f;
bool fixedRotation = (m_invIA + m_invIB == 0.0f);
// Solve angular limit constraint.
if (m_enableLimit && m_limitState != b2LimitState.e_inactiveLimit && fixedRotation == false)
{
float angle = aB - aA - m_referenceAngle;
float limitImpulse = 0.0f;
if (m_limitState == b2LimitState.e_equalLimits)
{
// Prevent large angular corrections
float C = b2Math.b2Clamp(angle - m_lowerAngle, -b2Settings.b2_maxAngularCorrection, b2Settings.b2_maxAngularCorrection);
limitImpulse = -m_motorMass * C;
angularError = b2Math.b2Abs(C);
}
else if (m_limitState == b2LimitState.e_atLowerLimit)
{
float C = angle - m_lowerAngle;
angularError = -C;
// Prevent large angular corrections and allow some slop.
C = b2Math.b2Clamp(C + b2Settings.b2_angularSlop, -b2Settings.b2_maxAngularCorrection, 0.0f);
limitImpulse = -m_motorMass * C;
}
else if (m_limitState == b2LimitState.e_atUpperLimit)
{
float C = angle - m_upperAngle;
angularError = C;
// Prevent large angular corrections and allow some slop.
C = b2Math.b2Clamp(C - b2Settings.b2_angularSlop, 0.0f, b2Settings.b2_maxAngularCorrection);
limitImpulse = -m_motorMass * C;
}
aA -= m_invIA * limitImpulse;
aB += m_invIB * limitImpulse;
}
// Solve point-to-point constraint.
{
qA.Set(aA);
qB.Set(aB);
b2Vec2 rA = b2Math.b2Mul(qA, m_localAnchorA - m_localCenterA);
b2Vec2 rB = b2Math.b2Mul(qB, m_localAnchorB - m_localCenterB);
b2Vec2 C = cB + rB - cA - rA;
positionError = C.Length();
float mA = m_invMassA, mB = m_invMassB;
float iA = m_invIA, iB = m_invIB;
b2Mat22 K = new b2Mat22();
K.exx = mA + mB + iA * rA.y * rA.y + iB * rB.y * rB.y;
K.exy = -iA * rA.x * rA.y - iB * rB.x * rB.y;
K.eyx = K.ex.y;
K.eyy = mA + mB + iA * rA.x * rA.x + iB * rB.x * rB.x;
b2Vec2 impulse = -K.Solve(C);
cA -= mA * impulse;
aA -= iA * b2Math.b2Cross(rA, impulse);
cB += mB * impulse;
aB += iB * b2Math.b2Cross(rB, impulse);
}
data.positions[m_indexA].c = cA;
data.positions[m_indexA].a = aA;
data.positions[m_indexB].c = cB;
data.positions[m_indexB].a = aB;
return positionError <= b2Settings.b2_linearSlop && angularError <= b2Settings.b2_angularSlop;
}
public override bool SolvePositionConstraints(b2SolverData data)
{
b2Vec2 cA = data.positions[m_indexA].c;
float aA = data.positions[m_indexA].a;
b2Vec2 cB = data.positions[m_indexB].c;
float aB = data.positions[m_indexB].a;
b2Rot qA = new b2Rot(aA);
b2Rot qB = new b2Rot(aB);
float mA = InvertedMassA, mB = InvertedMassB;
float iA = InvertedIA, iB = InvertedIB;
// Compute fresh Jacobians
b2Vec2 rA = b2Math.b2Mul(qA, m_localAnchorA - m_localCenterA);
b2Vec2 rB = b2Math.b2Mul(qB, m_localAnchorB - m_localCenterB);
b2Vec2 d = cB + rB - cA - rA;
b2Vec2 axis = b2Math.b2Mul(qA, m_localXAxisA);
float a1 = b2Math.b2Cross(d + rA, axis);
float a2 = b2Math.b2Cross(rB, axis);
b2Vec2 perp = b2Math.b2Mul(qA, m_localYAxisA);
float s1 = b2Math.b2Cross(d + rA, perp);
float s2 = b2Math.b2Cross(rB, perp);
b2Vec3 impulse;
b2Vec2 C1 = new b2Vec2();
C1.x = b2Math.b2Dot(perp, d);
C1.y = aB - aA - m_referenceAngle;
float linearError = b2Math.b2Abs(C1.x);
float angularError = b2Math.b2Abs(C1.y);
bool active = false;
float C2 = 0.0f;
if (m_enableLimit)
{
float translation = b2Math.b2Dot(axis, d);
if (b2Math.b2Abs(m_upperTranslation - m_lowerTranslation) < 2.0f * b2Settings.b2_linearSlop)
{
// Prevent large angular corrections
C2 = b2Math.b2Clamp(translation, -b2Settings.b2_maxLinearCorrection, b2Settings.b2_maxLinearCorrection);
linearError = Math.Max(linearError, b2Math.b2Abs(translation));
active = true;
}
else if (translation <= m_lowerTranslation)
{
// Prevent large linear corrections and allow some slop.
C2 = b2Math.b2Clamp(translation - m_lowerTranslation + b2Settings.b2_linearSlop, -b2Settings.b2_maxLinearCorrection, 0.0f);
linearError = Math.Max(linearError, m_lowerTranslation - translation);
active = true;
}
else if (translation >= m_upperTranslation)
{
// Prevent large linear corrections and allow some slop.
C2 = b2Math.b2Clamp(translation - m_upperTranslation - b2Settings.b2_linearSlop, 0.0f, b2Settings.b2_maxLinearCorrection);
linearError = Math.Max(linearError, translation - m_upperTranslation);
active = true;
}
}
if (active)
{
float k11 = mA + mB + iA * s1 * s1 + iB * s2 * s2;
float k12 = iA * s1 + iB * s2;
float k13 = iA * s1 * a1 + iB * s2 * a2;
float k22 = iA + iB;
if (k22 == 0.0f)
{
// For fixed rotation
k22 = 1.0f;
}
float k23 = iA * a1 + iB * a2;
float k33 = mA + mB + iA * a1 * a1 + iB * a2 * a2;
b2Mat33 K = new b2Mat33(
new b2Vec3(k11, k12, k13),
new b2Vec3(k12, k22, k23),
new b2Vec3(k13, k23, k33));
b2Vec3 C = new b2Vec3(C1.x, C1.y, C2);
impulse = K.Solve33(-C);
}
else
{
float k11 = mA + mB + iA * s1 * s1 + iB * s2 * s2;
float k12 = iA * s1 + iB * s2;
float k22 = iA + iB;
if (k22 == 0.0f)
{
k22 = 1.0f;
}
b2Mat22 K = new b2Mat22();
K.ex.Set(k11, k12);
K.ey.Set(k12, k22);
b2Vec2 impulse1 = K.Solve(-C1);
impulse = new b2Vec3();
impulse.x = impulse1.x;
impulse.y = impulse1.y;
impulse.z = 0.0f;
}
b2Vec2 P = impulse.x * perp + impulse.z * axis;
float LA = impulse.x * s1 + impulse.y + impulse.z * a1;
float LB = impulse.x * s2 + impulse.y + impulse.z * a2;
cA -= mA * P;
aA -= iA * LA;
cB += mB * P;
aB += iB * LB;
data.positions[m_indexA].c = cA;
data.positions[m_indexA].a = aA;
data.positions[m_indexB].c = cB;
data.positions[m_indexB].a = aB;
return linearError <= b2Settings.b2_linearSlop && angularError <= b2Settings.b2_angularSlop;
}
