public static b2Rot Create()
{
var rot = new b2Rot();
rot.SetIdentity();
return(rot);
}
public static b2Vec2 b2Mul(b2Rot q, b2Vec2 v)
{
b2Vec2 b;
b.x = q.c * v.x - q.s * v.y;
b.y = q.s * v.x + q.c * v.y;
return(b);
}
public static b2Vec2 b2MulT(b2Rot q, b2Vec2 v)
{
float x = q.c * v.x + q.s * v.y;
float y = -q.s * v.x + q.c * v.y;
b2Vec2 b = b2Vec2.Zero;
b.Set(x, y);
return b;
}
public static b2Vec2 b2MulT(ref b2Rot q, ref b2Vec2 v)
{
b2Vec2 b;
b.x = q.c * v.x + q.s * v.y;
b.y = -q.s * v.x + q.c * v.y;
return(b);
}
public static b2Rot b2MulT(b2Rot q, b2Rot r)
{
// [ qc qs] * [rc -rs] = [qc*rc+qs*rs -qc*rs+qs*rc]
// [-qs qc] [rs rc] [-qs*rc+qc*rs qs*rs+qc*rc]
// s = qc * rs - qs * rc
// c = qc * rc + qs * rs
b2Rot qr = b2Rot.Create();
qr.s = q.c * r.s - q.s * r.c;
qr.c = q.c * r.c + q.s * r.s;
return qr;
}
public static b2Rot b2Mul(b2Rot q, b2Rot r)
{
// [qc -qs] * [rc -rs] = [qc*rc-qs*rs -qc*rs-qs*rc]
// [qs qc] [rs rc] [qs*rc+qc*rs -qs*rs+qc*rc]
// s = qs * rc + qc * rs
// c = qc * rc - qs * rs
b2Rot qr;
qr.s = q.s * r.c + q.c * r.s;
qr.c = q.c * r.c - q.s * r.s;
return(qr);
}
public override bool SolvePositionConstraints(b2SolverData data)
{
b2Vec2 cA = m_bodyA.InternalPosition.c;
float aA = m_bodyA.InternalPosition.a;
b2Vec2 cB = m_bodyB.InternalPosition.c;
float aB = m_bodyB.InternalPosition.a;
b2Rot qA = new b2Rot(aA);
b2Rot qB = new b2Rot(aB);
b2Vec2 rA = b2Math.b2Mul(qA, m_localAnchorA - m_localCenterA);
b2Vec2 rB = b2Math.b2Mul(qB, m_localAnchorB - m_localCenterB);
// Get the pulley axes.
b2Vec2 uA = cA + rA - m_groundAnchorA;
b2Vec2 uB = cB + rB - m_groundAnchorB;
float lengthA = uA.Length;
float lengthB = uB.Length;
if (lengthA > 10.0f * b2Settings.b2_linearSlop)
{
uA *= 1.0f / lengthA;
}
else
{
uA.SetZero();
}
if (lengthB > 10.0f * b2Settings.b2_linearSlop)
{
uB *= 1.0f / lengthB;
}
else
{
uB.SetZero();
}
// Compute effective mass.
float ruA = b2Math.b2Cross(rA, uA);
float ruB = b2Math.b2Cross(rB, uB);
float mA = m_invMassA + m_invIA * ruA * ruA;
float mB = m_invMassB + m_invIB * ruB * ruB;
float mass = mA + m_ratio * m_ratio * mB;
if (mass > 0.0f)
{
mass = 1.0f / mass;
}
float C = m_constant - lengthA - m_ratio * lengthB;
float linearError = b2Math.b2Abs(C);
float impulse = -mass * C;
b2Vec2 PA = -impulse * uA;
b2Vec2 PB = -m_ratio * impulse * uB;
cA += m_invMassA * PA;
aA += m_invIA * b2Math.b2Cross(rA, PA);
cB += m_invMassB * PB;
aB += m_invIB * b2Math.b2Cross(rB, PB);
m_bodyA.InternalPosition.c = cA;
m_bodyA.InternalPosition.a = aA;
m_bodyB.InternalPosition.c = cB;
m_bodyB.InternalPosition.a = aB;
return linearError < b2Settings.b2_linearSlop;
}
/// The default ructor does nothing.
/*public b2Transform()
{
p = new b2Vec2();
q = new b2Rot();
}*/
/// Initialize using a position vector and a rotation.
b2Transform(b2Vec2 position, b2Rot rotation)
{
p = position;
q = rotation;
}
/// The default ructor does nothing.
/*public b2Transform()
* {
* p = new b2Vec2();
* q = new b2Rot();
* }*/
/// Initialize using a position vector and a rotation.
b2Transform(b2Vec2 position, b2Rot rotation)
{
p = position;
q = rotation;
}
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;
b2Vec2 cC = data.positions[m_indexC].c;
float aC = data.positions[m_indexC].a;
b2Vec2 cD = data.positions[m_indexD].c;
float aD = data.positions[m_indexD].a;
b2Rot qA = new b2Rot(aA);
b2Rot qB = new b2Rot(aB);
b2Rot qC = new b2Rot(aC);
b2Rot qD = new b2Rot(aD);
float linearError = 0.0f;
float coordinateA, coordinateB;
b2Vec2 JvAC = b2Vec2.Zero, JvBD = b2Vec2.Zero;
float JwA, JwB, JwC, JwD;
float mass = 0.0f;
if (m_typeA == b2JointType.e_revoluteJoint)
{
JvAC.SetZero();
JwA = 1.0f;
JwC = 1.0f;
mass += m_iA + m_iC;
coordinateA = aA - aC - m_referenceAngleA;
}
else
{
b2Vec2 u = b2Math.b2Mul(qC, m_localAxisC);
b2Vec2 rC = b2Math.b2Mul(qC, m_localAnchorC - m_lcC);
b2Vec2 rA = b2Math.b2Mul(qA, m_localAnchorA - m_lcA);
JvAC = u;
JwC = b2Math.b2Cross(rC, u);
JwA = b2Math.b2Cross(rA, u);
mass += m_mC + m_mA + m_iC * JwC * JwC + m_iA * JwA * JwA;
b2Vec2 pC = m_localAnchorC - m_lcC;
b2Vec2 pA = b2Math.b2MulT(qC, rA + (cA - cC));
coordinateA = b2Math.b2Dot(pA - pC, m_localAxisC);
}
if (m_typeB == b2JointType.e_revoluteJoint)
{
JvBD.SetZero();
JwB = m_ratio;
JwD = m_ratio;
mass += m_ratio * m_ratio * (m_iB + m_iD);
coordinateB = aB - aD - m_referenceAngleB;
}
else
{
b2Vec2 u = b2Math.b2Mul(qD, m_localAxisD);
b2Vec2 rD = b2Math.b2Mul(qD, m_localAnchorD - m_lcD);
b2Vec2 rB = b2Math.b2Mul(qB, m_localAnchorB - m_lcB);
JvBD = m_ratio * u;
JwD = m_ratio * b2Math.b2Cross(rD, u);
JwB = m_ratio * b2Math.b2Cross(rB, u);
mass += m_ratio * m_ratio * (m_mD + m_mB) + m_iD * JwD * JwD + m_iB * JwB * JwB;
b2Vec2 pD = m_localAnchorD - m_lcD;
b2Vec2 pB = b2Math.b2MulT(qD, rB + (cB - cD));
coordinateB = b2Math.b2Dot(pB - pD, m_localAxisD);
}
float C = (coordinateA + m_ratio * coordinateB) - m_constant;
float impulse = 0.0f;
if (mass > 0.0f)
{
impulse = -C / mass;
}
cA += m_mA * impulse * JvAC;
aA += m_iA * impulse * JwA;
cB += m_mB * impulse * JvBD;
aB += m_iB * impulse * JwB;
cC -= m_mC * impulse * JvAC;
aC -= m_iC * impulse * JwC;
cD -= m_mD * impulse * JvBD;
aD -= m_iD * impulse * JwD;
data.positions[m_indexA].c = cA;
data.positions[m_indexA].a = aA;
data.positions[m_indexB].c = cB;
data.positions[m_indexB].a = aB;
data.positions[m_indexC].c = cC;
data.positions[m_indexC].a = aC;
data.positions[m_indexD].c = cD;
data.positions[m_indexD].a = aD;
// TODO_ERIN not implemented
return linearError < b2Settings.b2_linearSlop;
}
public override void InitVelocityConstraints(b2SolverData data)
{
m_indexA = m_bodyA.IslandIndex;
m_indexB = m_bodyB.IslandIndex;
m_localCenterA = m_bodyA.Sweep.localCenter;
m_localCenterB = m_bodyB.Sweep.localCenter;
m_invMassA = m_bodyA.InvertedMass;
m_invMassB = m_bodyB.InvertedMass;
m_invIA = m_bodyA.InvertedI;
m_invIB = m_bodyB.InvertedI;
b2Vec2 cA = data.positions[m_indexA].c;
float aA = data.positions[m_indexA].a;
b2Vec2 vA = data.velocities[m_indexA].v;
float wA = data.velocities[m_indexA].w;
b2Vec2 cB = data.positions[m_indexB].c;
float aB = data.positions[m_indexB].a;
b2Vec2 vB = data.velocities[m_indexB].v;
float wB = data.velocities[m_indexB].w;
b2Rot qA = new b2Rot(aA);
b2Rot qB = new b2Rot(aB);
m_rA = b2Math.b2Mul(qA, m_localAnchorA - m_localCenterA);
m_rB = b2Math.b2Mul(qB, m_localAnchorB - m_localCenterB);
// 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;
bool fixedRotation = (iA + iB == 0.0f);
b2Vec3 ex = new b2Vec3();
b2Vec3 ey = new b2Vec3();
b2Vec3 ez = new b2Vec3();
ex.x = mA + mB + m_rA.y * m_rA.y * iA + m_rB.y * m_rB.y * iB;
ey.x = -m_rA.y * m_rA.x * iA - m_rB.y * m_rB.x * iB;
ez.x = -m_rA.y * iA - m_rB.y * iB;
ex.y = ey.x;
ey.y = mA + mB + m_rA.x * m_rA.x * iA + m_rB.x * m_rB.x * iB;
ez.y = m_rA.x * iA + m_rB.x * iB;
ex.z = ez.x;
ey.z = ez.y;
ez.z = iA + iB;
m_mass = new b2Mat33(ex, ey, ez);
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 (b2Math.b2Abs(m_upperAngle - m_lowerAngle) < 2.0f * b2Settings.b2_angularSlop)
{
m_limitState = b2LimitState.e_equalLimits;
}
else if (jointAngle <= m_lowerAngle)
{
if (m_limitState != b2LimitState.e_atLowerLimit)
{
m_impulse.z = 0.0f;
}
m_limitState = b2LimitState.e_atLowerLimit;
}
else if (jointAngle >= m_upperAngle)
{
if (m_limitState != b2LimitState.e_atUpperLimit)
{
m_impulse.z = 0.0f;
}
m_limitState = b2LimitState.e_atUpperLimit;
}
else
{
m_limitState = b2LimitState.e_inactiveLimit;
m_impulse.z = 0.0f;
}
}
else
{
m_limitState = b2LimitState.e_inactiveLimit;
}
if (data.step.warmStarting)
{
// Scale impulses to support a variable time step.
m_impulse *= data.step.dtRatio;
m_motorImpulse *= data.step.dtRatio;
b2Vec2 P = new b2Vec2(m_impulse.x, m_impulse.y);
vA -= mA * P;
wA -= iA * (b2Math.b2Cross(m_rA, P) + m_motorImpulse + m_impulse.z);
vB += mB * P;
wB += iB * (b2Math.b2Cross(m_rB, P) + m_motorImpulse + m_impulse.z);
}
else
{
m_impulse.SetZero();
m_motorImpulse = 0.0f;
}
data.velocities[m_indexA].v = vA;
data.velocities[m_indexA].w = wA;
data.velocities[m_indexB].v = vB;
data.velocities[m_indexB].w = wB;
}
public override void InitVelocityConstraints(b2SolverData data)
{
m_indexA = m_bodyA.IslandIndex;
m_indexB = m_bodyB.IslandIndex;
m_localCenterA = m_bodyA.Sweep.localCenter;
m_localCenterB = m_bodyB.Sweep.localCenter;
m_invMassA = m_bodyA.InvertedMass;
m_invMassB = m_bodyB.InvertedMass;
m_invIA = m_bodyA.InvertedI;
m_invIB = m_bodyB.InvertedI;
b2Vec2 cA = m_bodyA.InternalPosition.c;
float aA = m_bodyA.InternalPosition.a;
b2Vec2 vA = m_bodyA.InternalVelocity.v;
float wA = m_bodyA.InternalVelocity.w;
b2Vec2 cB = m_bodyB.InternalPosition.c;
float aB = m_bodyB.InternalPosition.a;
b2Vec2 vB = m_bodyB.InternalVelocity.v;
float wB = m_bodyB.InternalVelocity.w;
b2Rot qA = new b2Rot(aA);
b2Rot qB = new b2Rot(aB);
m_rA = b2Math.b2Mul(qA, m_localAnchorA - m_localCenterA);
m_rB = b2Math.b2Mul(qB, m_localAnchorB - m_localCenterB);
// 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;
b2Vec3 ex = new b2Vec3();
b2Vec3 ey = new b2Vec3();
b2Vec3 ez = new b2Vec3();
ex.x = mA + mB + m_rA.y * m_rA.y * iA + m_rB.y * m_rB.y * iB;
ey.x = -m_rA.y * m_rA.x * iA - m_rB.y * m_rB.x * iB;
ez.x = -m_rA.y * iA - m_rB.y * iB;
ex.y = ey.x;
ey.y = mA + mB + m_rA.x * m_rA.x * iA + m_rB.x * m_rB.x * iB;
ez.y = m_rA.x * iA + m_rB.x * iB;
ex.z = ez.x;
ey.z = ez.y;
ez.z = iA + iB;
b2Mat33 K = new b2Mat33(ex, ey, ez);
if (m_frequencyHz > 0.0f)
{
m_mass = K.GetInverse22(m_mass);
float invM = iA + iB;
float m = invM > 0.0f ? 1.0f / invM : 0.0f;
float C = aB - aA - m_referenceAngle;
// Frequency
float omega = 2.0f * b2Settings.b2_pi * m_frequencyHz;
// Damping coefficient
float d = 2.0f * m * m_dampingRatio * omega;
// Spring stiffness
float k = m * omega * omega;
// magic formulas
float h = data.step.dt;
m_gamma = h * (d + h * k);
m_gamma = m_gamma != 0.0f ? 1.0f / m_gamma : 0.0f;
m_bias = C * h * k * m_gamma;
invM += m_gamma;
m_mass.ezz = invM != 0.0f ? 1.0f / invM : 0.0f;
}
else
{
m_mass = K.GetSymInverse33(m_mass);
m_gamma = 0.0f;
m_bias = 0.0f;
}
if (data.step.warmStarting)
{
// Scale impulses to support a variable time step.
m_impulse *= data.step.dtRatio;
b2Vec2 P = new b2Vec2(m_impulse.x, m_impulse.y);
vA -= mA * P;
wA -= iA * (b2Math.b2Cross(m_rA, P) + m_impulse.z);
vB += mB * P;
wB += iB * (b2Math.b2Cross(m_rB, P) + m_impulse.z);
}
else
{
m_impulse.SetZero();
}
m_bodyA.InternalVelocity.v = vA;
m_bodyA.InternalVelocity.w = wA;
m_bodyB.InternalVelocity.v = vB;
m_bodyB.InternalVelocity.w = wB;
}
public override void InitVelocityConstraints(b2SolverData data)
{
m_indexA = m_bodyA.IslandIndex;
m_indexB = m_bodyB.IslandIndex;
m_localCenterA = m_bodyA.Sweep.localCenter;
m_localCenterB = m_bodyB.Sweep.localCenter;
m_invMassA = m_bodyA.InvertedMass;
m_invMassB = m_bodyB.InvertedMass;
m_invIA = m_bodyA.InvertedI;
m_invIB = m_bodyB.InvertedI;
b2Vec2 cA = m_bodyA.InternalPosition.c;
float aA = m_bodyA.InternalPosition.a;
b2Vec2 vA = m_bodyA.InternalVelocity.v;
float wA = m_bodyA.InternalVelocity.w;
b2Vec2 cB = m_bodyB.InternalPosition.c;
float aB = m_bodyB.InternalPosition.a;
b2Vec2 vB = m_bodyB.InternalVelocity.v;
float wB = m_bodyB.InternalVelocity.w;
b2Rot qA = new b2Rot(aA);
b2Rot qB = new b2Rot(aB);
m_rA = b2Math.b2Mul(qA, m_localAnchorA - m_localCenterA);
m_rB = b2Math.b2Mul(qB, m_localAnchorB - m_localCenterB);
m_u = cB + m_rB - cA - m_rA;
m_length = m_u.Length;
float C = m_length - m_maxLength;
if (C > 0.0f)
{
m_state = b2LimitState.e_atUpperLimit;
}
else
{
m_state = b2LimitState.e_inactiveLimit;
}
if (m_length > b2Settings.b2_linearSlop)
{
m_u *= 1.0f / m_length;
}
else
{
m_u.SetZero();
m_mass = 0.0f;
m_impulse = 0.0f;
return;
}
// Compute effective mass.
float crA = b2Math.b2Cross(m_rA, m_u);
float crB = b2Math.b2Cross(m_rB, m_u);
float invMass = m_invMassA + m_invIA * crA * crA + m_invMassB + m_invIB * crB * crB;
m_mass = invMass != 0.0f ? 1.0f / invMass : 0.0f;
if (data.step.warmStarting)
{
// Scale the impulse to support a variable time step.
m_impulse *= data.step.dtRatio;
b2Vec2 P = m_impulse * m_u;
vA -= m_invMassA * P;
wA -= m_invIA * b2Math.b2Cross(m_rA, P);
vB += m_invMassB * P;
wB += m_invIB * b2Math.b2Cross(m_rB, P);
}
else
{
m_impulse = 0.0f;
}
m_bodyA.InternalVelocity.v = vA;
m_bodyA.InternalVelocity.w = wA;
m_bodyB.InternalVelocity.v = vB;
m_bodyB.InternalVelocity.w = wB;
}
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;
}
public override void InitVelocityConstraints(b2SolverData data)
{
m_indexB = m_bodyB.IslandIndex;
m_localCenterB = m_bodyB.Sweep.localCenter;
m_invMassB = m_bodyB.InvertedMass;
m_invIB = m_bodyB.InvertedI;
b2Vec2 cB = data.positions[m_indexB].c;
float aB = data.positions[m_indexB].a;
b2Vec2 vB = data.velocities[m_indexB].v;
float wB = data.velocities[m_indexB].w;
b2Rot qB = new b2Rot(aB);
float mass = m_bodyB.Mass;
// Frequency
float omega = 2.0f * b2Settings.b2_pi * m_frequencyHz;
// Damping coefficient
float d = 2.0f * mass * m_dampingRatio * omega;
// Spring stiffness
float k = mass * (omega * omega);
// magic formulas
// gamma has units of inverse mass.
// beta has units of inverse time.
float h = data.step.dt;
Debug.Assert(d + h * k > b2Settings.b2_epsilon);
m_gamma = h * (d + h * k);
if (m_gamma != 0.0f)
{
m_gamma = 1.0f / m_gamma;
}
m_beta = h * k * m_gamma;
// Compute the effective mass matrix.
m_rB = b2Math.b2Mul(qB, m_localAnchorB - m_localCenterB);
// K = [(1/m1 + 1/m2) * eye(2) - skew(r1) * invI1 * skew(r1) - skew(r2) * invI2 * skew(r2)]
// = [1/m1+1/m2 0 ] + invI1 * [r1.y*r1.y -r1.x*r1.y] + invI2 * [r1.y*r1.y -r1.x*r1.y]
// [ 0 1/m1+1/m2] [-r1.x*r1.y r1.x*r1.x] [-r1.x*r1.y r1.x*r1.x]
b2Mat22 K = new b2Mat22();
K.exx = m_invMassB + m_invIB * m_rB.y * m_rB.y + m_gamma;
K.exy = -m_invIB * m_rB.x * m_rB.y;
K.eyx = K.ex.y;
K.eyy = m_invMassB + m_invIB * m_rB.x * m_rB.x + m_gamma;
m_mass = K.GetInverse();
m_C = cB + m_rB - m_targetA;
m_C *= m_beta;
// Cheat with some damping
wB *= 0.98f;
if (data.step.warmStarting)
{
m_impulse *= data.step.dtRatio;
vB += m_invMassB * m_impulse;
wB += m_invIB * b2Math.b2Cross(m_rB, m_impulse);
}
else
{
m_impulse.SetZero();
}
data.velocities[m_indexB].v = vB;
data.velocities[m_indexB].w = wB;
}
public override void InitVelocityConstraints(b2SolverData data)
{
m_indexA = m_bodyA.IslandIndex;
m_indexB = m_bodyB.IslandIndex;
m_localCenterA = m_bodyA.Sweep.localCenter;
m_localCenterB = m_bodyB.Sweep.localCenter;
InvertedMassA = m_bodyA.InvertedMass;
InvertedMassB = m_bodyB.InvertedMass;
InvertedIA = m_bodyA.InvertedI;
InvertedIB = m_bodyB.InvertedI;
b2Vec2 cA = data.positions[m_indexA].c;
float aA = data.positions[m_indexA].a;
b2Vec2 vA = data.velocities[m_indexA].v;
float wA = data.velocities[m_indexA].w;
b2Vec2 cB = data.positions[m_indexB].c;
float aB = data.positions[m_indexB].a;
b2Vec2 vB = data.velocities[m_indexB].v;
float wB = data.velocities[m_indexB].w;
b2Rot qA = new b2Rot(aA);
b2Rot qB = new b2Rot(aB);
// Compute the effective masses.
b2Vec2 rA = b2Math.b2Mul(qA, m_localAnchorA - m_localCenterA);
b2Vec2 rB = b2Math.b2Mul(qB, m_localAnchorB - m_localCenterB);
b2Vec2 d = (cB - cA) + rB - rA;
float mA = InvertedMassA, mB = InvertedMassB;
float iA = InvertedIA, iB = InvertedIB;
// Compute motor Jacobian and effective mass.
{
m_axis = b2Math.b2Mul(qA, m_localXAxisA);
m_a1 = b2Math.b2Cross(d + rA, m_axis);
m_a2 = b2Math.b2Cross(rB, m_axis);
m_motorMass = mA + mB + iA * m_a1 * m_a1 + iB * m_a2 * m_a2;
if (m_motorMass > 0.0f)
{
m_motorMass = 1.0f / m_motorMass;
}
}
// Prismatic constraint.
{
m_perp = b2Math.b2Mul(qA, m_localYAxisA);
m_s1 = b2Math.b2Cross(d + rA, m_perp);
m_s2 = b2Math.b2Cross(rB, m_perp);
float k11 = mA + mB + iA * m_s1 * m_s1 + iB * m_s2 * m_s2;
float k12 = iA * m_s1 + iB * m_s2;
float k13 = iA * m_s1 * m_a1 + iB * m_s2 * m_a2;
float k22 = iA + iB;
if (k22 == 0.0f)
{
// For bodies with fixed rotation.
k22 = 1.0f;
}
float k23 = iA * m_a1 + iB * m_a2;
float k33 = mA + mB + iA * m_a1 * m_a1 + iB * m_a2 * m_a2;
m_K.ex.Set(k11, k12, k13);
m_K.ey.Set(k12, k22, k23);
m_K.ez.Set(k13, k23, k33);
}
// Compute motor and limit terms.
if (m_enableLimit)
{
float jointTranslation = b2Math.b2Dot(m_axis, d);
if (b2Math.b2Abs(m_upperTranslation - m_lowerTranslation) < 2.0f * b2Settings.b2_linearSlop)
{
m_limitState = b2LimitState.e_equalLimits;
}
else if (jointTranslation <= m_lowerTranslation)
{
if (m_limitState != b2LimitState.e_atLowerLimit)
{
m_limitState = b2LimitState.e_atLowerLimit;
m_impulse.z = 0.0f;
}
}
else if (jointTranslation >= m_upperTranslation)
{
if (m_limitState != b2LimitState.e_atUpperLimit)
{
m_limitState = b2LimitState.e_atUpperLimit;
m_impulse.z = 0.0f;
}
}
else
{
m_limitState = b2LimitState.e_inactiveLimit;
m_impulse.z = 0.0f;
}
}
else
{
m_limitState = b2LimitState.e_inactiveLimit;
m_impulse.z = 0.0f;
}
if (m_enableMotor == false)
{
m_motorImpulse = 0.0f;
}
if (data.step.warmStarting)
{
// Account for variable time step.
m_impulse *= data.step.dtRatio;
m_motorImpulse *= data.step.dtRatio;
b2Vec2 P = m_impulse.x * m_perp + (m_motorImpulse + m_impulse.z) * m_axis;
float LA = m_impulse.x * m_s1 + m_impulse.y + (m_motorImpulse + m_impulse.z) * m_a1;
float LB = m_impulse.x * m_s2 + m_impulse.y + (m_motorImpulse + m_impulse.z) * m_a2;
vA -= mA * P;
wA -= iA * LA;
vB += mB * P;
wB += iB * LB;
}
else
{
m_impulse.SetZero();
m_motorImpulse = 0.0f;
}
data.velocities[m_indexA].v = vA;
data.velocities[m_indexA].w = wA;
data.velocities[m_indexB].v = vB;
data.velocities[m_indexB].w = wB;
}
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);
b2Vec2 rA = b2Math.b2Mul(qA, m_localAnchorA - m_localCenterA);
b2Vec2 rB = b2Math.b2Mul(qB, m_localAnchorB - m_localCenterB);
b2Vec2 d = (cB - cA) + rB - rA;
b2Vec2 ay = b2Math.b2Mul(qA, m_localYAxisA);
float sAy = b2Math.b2Cross(d + rA, ay);
float sBy = b2Math.b2Cross(rB, ay);
float C = b2Math.b2Dot(d, ay);
float k = m_invMassA + m_invMassB + m_invIA * m_sAy * m_sAy + m_invIB * m_sBy * m_sBy;
float impulse;
if (k != 0.0f)
{
impulse = -C / k;
}
else
{
impulse = 0.0f;
}
b2Vec2 P = impulse * ay;
float LA = impulse * sAy;
float LB = impulse * sBy;
cA -= m_invMassA * P;
aA -= m_invIA * LA;
cB += m_invMassB * P;
aB += m_invIB * 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 b2Math.b2Abs(C) <= b2Settings.b2_linearSlop;
}
public override void InitVelocityConstraints(b2SolverData data)
{
m_indexA = m_bodyA.IslandIndex;
m_indexB = m_bodyB.IslandIndex;
m_localCenterA = m_bodyA.Sweep.localCenter;
m_localCenterB = m_bodyB.Sweep.localCenter;
m_invMassA = m_bodyA.InvertedMass;
m_invMassB = m_bodyB.InvertedMass;
m_invIA = m_bodyA.InvertedI;
m_invIB = m_bodyB.InvertedI;
float mA = m_invMassA, mB = m_invMassB;
float iA = m_invIA, iB = m_invIB;
b2Vec2 cA = data.positions[m_indexA].c;
float aA = data.positions[m_indexA].a;
b2Vec2 vA = data.velocities[m_indexA].v;
float wA = data.velocities[m_indexA].w;
b2Vec2 cB = data.positions[m_indexB].c;
float aB = data.positions[m_indexB].a;
b2Vec2 vB = data.velocities[m_indexB].v;
float wB = data.velocities[m_indexB].w;
b2Rot qA = new b2Rot(aA);
b2Rot qB = new b2Rot(aB);
// Compute the effective masses.
b2Vec2 rA = b2Math.b2Mul(qA, m_localAnchorA - m_localCenterA);
b2Vec2 rB = b2Math.b2Mul(qB, m_localAnchorB - m_localCenterB);
b2Vec2 d = cB + rB - cA - rA;
// Point to line raint
{
m_ay = b2Math.b2Mul(qA, m_localYAxisA);
m_sAy = b2Math.b2Cross(d + rA, m_ay);
m_sBy = b2Math.b2Cross(rB, m_ay);
m_mass = mA + mB + iA * m_sAy * m_sAy + iB * m_sBy * m_sBy;
if (m_mass > 0.0f)
{
m_mass = 1.0f / m_mass;
}
}
// Spring raint
m_springMass = 0.0f;
m_bias = 0.0f;
m_gamma = 0.0f;
if (m_frequencyHz > 0.0f)
{
m_ax = b2Math.b2Mul(qA, m_localXAxisA);
m_sAx = b2Math.b2Cross(d + rA, m_ax);
m_sBx = b2Math.b2Cross(rB, m_ax);
float invMass = mA + mB + iA * m_sAx * m_sAx + iB * m_sBx * m_sBx;
if (invMass > 0.0f)
{
m_springMass = 1.0f / invMass;
float C = b2Math.b2Dot(d, m_ax);
// Frequency
float omega = 2.0f * (float)Math.PI * m_frequencyHz;
// Damping coefficient
float dx = 2.0f * m_springMass * m_dampingRatio * omega;
// Spring stiffness
float k = m_springMass * omega * omega;
// magic formulas
float h = data.step.dt;
m_gamma = h * (dx + h * k);
if (m_gamma > 0.0f)
{
m_gamma = 1.0f / m_gamma;
}
m_bias = C * h * k * m_gamma;
m_springMass = invMass + m_gamma;
if (m_springMass > 0.0f)
{
m_springMass = 1.0f / m_springMass;
}
}
}
else
{
m_springImpulse = 0.0f;
}
// Rotational motor
if (m_enableMotor)
{
m_motorMass = iA + iB;
if (m_motorMass > 0.0f)
{
m_motorMass = 1.0f / m_motorMass;
}
}
else
{
m_motorMass = 0.0f;
m_motorImpulse = 0.0f;
}
if (data.step.warmStarting)
{
// Account for variable time step.
m_impulse *= data.step.dtRatio;
m_springImpulse *= data.step.dtRatio;
m_motorImpulse *= data.step.dtRatio;
b2Vec2 P = m_impulse * m_ay + m_springImpulse * m_ax;
float LA = m_impulse * m_sAy + m_springImpulse * m_sAx + m_motorImpulse;
float LB = m_impulse * m_sBy + m_springImpulse * m_sBx + m_motorImpulse;
vA -= m_invMassA * P;
wA -= m_invIA * LA;
vB += m_invMassB * P;
wB += m_invIB * LB;
}
else
{
m_impulse = 0.0f;
m_springImpulse = 0.0f;
m_motorImpulse = 0.0f;
}
data.velocities[m_indexA].v = vA;
data.velocities[m_indexA].w = wA;
data.velocities[m_indexB].v = vB;
data.velocities[m_indexB].w = wB;
}
/// Inverse rotate a vector
public static b2Vec2 b2MulT(b2Rot q, b2Vec2 v)
{
return(new b2Vec2(q.c * v.x + q.s * v.y, -q.s * v.x + q.c * v.y));
}
public override void InitVelocityConstraints(b2SolverData data)
{
m_indexA = m_bodyA.IslandIndex;
m_indexB = m_bodyB.IslandIndex;
m_localCenterA = m_bodyA.Sweep.localCenter;
m_localCenterB = m_bodyB.Sweep.localCenter;
m_invMassA = m_bodyA.InvertedMass;
m_invMassB = m_bodyB.InvertedMass;
m_invIA = m_bodyA.InvertedI;
m_invIB = m_bodyB.InvertedI;
b2Vec2 cA = m_bodyA.InternalPosition.c;
float aA = m_bodyA.InternalPosition.a;
b2Vec2 vA = m_bodyA.InternalVelocity.v;
float wA = m_bodyA.InternalVelocity.w;
b2Vec2 cB = m_bodyB.InternalPosition.c;
float aB = m_bodyB.InternalPosition.a;
b2Vec2 vB = m_bodyB.InternalVelocity.v;
float wB = m_bodyB.InternalVelocity.w;
b2Rot qA = new b2Rot(aA);
b2Rot qB = new b2Rot(aB);
m_rA = b2Math.b2Mul(qA, m_localAnchorA - m_localCenterA);
m_rB = b2Math.b2Mul(qB, m_localAnchorB - m_localCenterB);
// Get the pulley axes.
m_uA = cA + m_rA - m_groundAnchorA;
m_uB = cB + m_rB - m_groundAnchorB;
float lengthA = m_uA.Length;
float lengthB = m_uB.Length;
if (lengthA > 10.0f * b2Settings.b2_linearSlop)
{
m_uA *= 1.0f / lengthA;
}
else
{
m_uA.SetZero();
}
if (lengthB > 10.0f * b2Settings.b2_linearSlop)
{
m_uB *= 1.0f / lengthB;
}
else
{
m_uB.SetZero();
}
// Compute effective mass.
float ruA = b2Math.b2Cross(m_rA, m_uA);
float ruB = b2Math.b2Cross(m_rB, m_uB);
float mA = m_invMassA + m_invIA * ruA * ruA;
float mB = m_invMassB + m_invIB * ruB * ruB;
m_mass = mA + m_ratio * m_ratio * mB;
if (m_mass > 0.0f)
{
m_mass = 1.0f / m_mass;
}
if (data.step.warmStarting)
{
// Scale impulses to support variable time steps.
m_impulse *= data.step.dtRatio;
// Warm starting.
b2Vec2 PA = -(m_impulse) * m_uA;
b2Vec2 PB = (-m_ratio * m_impulse) * m_uB;
vA += m_invMassA * PA;
wA += m_invIA * b2Math.b2Cross(m_rA, PA);
vB += m_invMassB * PB;
wB += m_invIB * b2Math.b2Cross(m_rB, PB);
}
else
{
m_impulse = 0.0f;
}
m_bodyA.InternalVelocity.v = vA;
m_bodyA.InternalVelocity.w = wA;
m_bodyB.InternalVelocity.v = vB;
m_bodyB.InternalVelocity.w = wB;
}
/// <summary>
/// Actualizamos las imagenes de los cuerpos con las fisicas
/// </summary>
public virtual void OnSetImagePositionsFromPhysicsBodies()
{
foreach (var imgInfo in m_imageInfos)
{
if (imgInfo != null)
{
var pos = imgInfo.Center;
float angle = -imgInfo.Angle;
if (imgInfo.Body != null)
{
//need to rotate image local center by body angle
b2Vec2 localPos = new b2Vec2(pos.x, pos.y);
b2Rot rot = new b2Rot(imgInfo.Body.Angle);
localPos = CCPointExHelper.b2Mul(rot, localPos) + imgInfo.Body.Position;
pos.x = localPos.x;
pos.y = localPos.y;
angle += -imgInfo.Body.Angle;
}
imgInfo.Sprite.Rotation = CCMathHelper.ToDegrees(angle);
imgInfo.Sprite.Position = new CCPoint(pos.x, pos.y);
}
}
}
public override bool SolvePositionConstraints(b2SolverData data)
{
b2Vec2 cA = m_bodyA.InternalPosition.c;
float aA = m_bodyA.InternalPosition.a;
b2Vec2 cB = m_bodyB.InternalPosition.c;
float aB = m_bodyB.InternalPosition.a;
b2Rot qA = new b2Rot(aA);
b2Rot qB = new b2Rot(aB);
b2Vec2 rA = b2Math.b2Mul(qA, m_localAnchorA - m_localCenterA);
b2Vec2 rB = b2Math.b2Mul(qB, m_localAnchorB - m_localCenterB);
b2Vec2 u = cB + rB - cA - rA;
float length = u.Normalize();
float C = length - m_maxLength;
C = b2Math.b2Clamp(C, 0.0f, b2Settings.b2_maxLinearCorrection);
float impulse = -m_mass * C;
b2Vec2 P = impulse * u;
cA -= m_invMassA * P;
aA -= m_invIA * b2Math.b2Cross(rA, P);
cB += m_invMassB * P;
aB += m_invIB * b2Math.b2Cross(rB, P);
m_bodyA.InternalPosition.c = cA;
m_bodyA.InternalPosition.a = aA;
m_bodyB.InternalPosition.c = cB;
m_bodyB.InternalPosition.a = aB;
return length - m_maxLength < b2Settings.b2_linearSlop;
}
public static b2Rot Create()
{
var rot = new b2Rot();
rot.SetIdentity();
return rot;
}
public override bool SolvePositionConstraints(b2SolverData data)
{
b2Vec2 cA = m_bodyA.InternalPosition.c;
float aA = m_bodyA.InternalPosition.a;
b2Vec2 cB = m_bodyB.InternalPosition.c;
float aB = m_bodyB.InternalPosition.a;
b2Rot qA = new b2Rot(aA);
b2Rot qB = new b2Rot(aB);
float mA = m_invMassA, mB = m_invMassB;
float iA = m_invIA, iB = m_invIB;
b2Vec2 rA = b2Math.b2Mul(qA, m_localAnchorA - m_localCenterA);
b2Vec2 rB = b2Math.b2Mul(qB, m_localAnchorB - m_localCenterB);
float positionError, angularError;
b2Vec3 ex = new b2Vec3();
b2Vec3 ey = new b2Vec3();
b2Vec3 ez = new b2Vec3();
ex.x = mA + mB + rA.y * rA.y * iA + rB.y * rB.y * iB;
ey.x = -rA.y * rA.x * iA - rB.y * rB.x * iB;
ez.x = -rA.y * iA - rB.y * iB;
ex.y = ey.x;
ey.y = mA + mB + rA.x * rA.x * iA + rB.x * rB.x * iB;
ez.y = rA.x * iA + rB.x * iB;
ex.z = ez.x;
ey.z = ez.y;
ez.z = iA + iB;
b2Mat33 K = new b2Mat33(ex, ey, ez);
if (m_frequencyHz > 0.0f)
{
b2Vec2 C1 = cB + rB - cA - rA;
positionError = C1.Length;
angularError = 0.0f;
b2Vec2 P = -K.Solve22(C1);
cA -= mA * P;
aA -= iA * b2Math.b2Cross(rA, P);
cB += mB * P;
aB += iB * b2Math.b2Cross(rB, P);
}
else
{
b2Vec2 C1 = cB + rB - cA - rA;
float C2 = aB - aA - m_referenceAngle;
positionError = C1.Length;
angularError = b2Math.b2Abs(C2);
b2Vec3 C = new b2Vec3(C1.x, C1.y, C2);
b2Vec3 impulse = -K.Solve33(C);
b2Vec2 P = new b2Vec2(impulse.x, impulse.y);
cA -= mA * P;
aA -= iA * (b2Math.b2Cross(rA, P) + impulse.z);
cB += mB * P;
aB += iB * (b2Math.b2Cross(rB, P) + impulse.z);
}
m_bodyA.InternalPosition.c = cA;
m_bodyA.InternalPosition.a = aA;
m_bodyB.InternalPosition.c = cB;
m_bodyB.InternalPosition.a = aB;
return positionError <= b2Settings.b2_linearSlop && angularError <= b2Settings.b2_angularSlop;
}
public override bool SolvePositionConstraints(b2SolverData data)
{
if (m_frequencyHz > 0.0f)
{
// There is no position correction for soft distance constraints.
return true;
}
b2Vec2 cA = m_bodyA.InternalPosition.c;
float aA = m_bodyA.InternalPosition.a;
b2Vec2 cB = m_bodyB.InternalPosition.c;
float aB = m_bodyB.InternalPosition.a;
b2Rot qA = new b2Rot(aA);
b2Rot qB = new b2Rot(aB);
b2Vec2 rA = b2Math.b2Mul(qA, m_localAnchorA - m_localCenterA);
b2Vec2 rB = b2Math.b2Mul(qB, m_localAnchorB - m_localCenterB);
b2Vec2 u = cB + rB - cA - rA;
float length = u.Normalize();
float C = length - m_length;
C = b2Math.b2Clamp(C, -b2Settings.b2_maxLinearCorrection, b2Settings.b2_maxLinearCorrection);
float impulse = -m_mass * C;
b2Vec2 P = impulse * u;
cA -= m_invMassA * P;
aA -= m_invIA * b2Math.b2Cross(ref rA, ref P);
cB += m_invMassB * P;
aB += m_invIB * b2Math.b2Cross(ref rB, ref P);
m_bodyA.InternalPosition.c = cA;
m_bodyA.InternalPosition.a = aA;
m_bodyB.InternalPosition.c = cB;
m_bodyB.InternalPosition.a = aB;
return b2Math.b2Abs(C) < b2Settings.b2_linearSlop;
}
public override void InitVelocityConstraints(b2SolverData data)
{
m_indexA = m_bodyA.IslandIndex;
m_indexB = m_bodyB.IslandIndex;
m_localCenterA = m_bodyA.Sweep.localCenter;
m_localCenterB = m_bodyB.Sweep.localCenter;
m_invMassA = m_bodyA.InvertedMass;
m_invMassB = m_bodyB.InvertedMass;
m_invIA = m_bodyA.InvertedI;
m_invIB = m_bodyB.InvertedI;
float aA = m_bodyA.InternalPosition.a;
b2Vec2 vA = m_bodyA.InternalVelocity.v;
float wA = m_bodyA.InternalVelocity.w;
float aB = m_bodyB.InternalPosition.a;
b2Vec2 vB = m_bodyB.InternalVelocity.v;
float wB = m_bodyB.InternalVelocity.w;
b2Rot qA = new b2Rot(aA);
b2Rot qB = new b2Rot(aB);
// Compute the effective mass matrix.
m_rA = b2Math.b2Mul(qA, m_localAnchorA - m_localCenterA);
m_rB = b2Math.b2Mul(qB, m_localAnchorB - m_localCenterB);
// 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;
b2Mat22 K = new b2Mat22();
K.exx = mA + mB + iA * m_rA.y * m_rA.y + iB * m_rB.y * m_rB.y;
K.exy = -iA * m_rA.x * m_rA.y - iB * m_rB.x * m_rB.y;
K.eyx = K.ex.y;
K.eyy = mA + mB + iA * m_rA.x * m_rA.x + iB * m_rB.x * m_rB.x;
m_linearMass = K.GetInverse();
m_angularMass = iA + iB;
if (m_angularMass > 0.0f)
{
m_angularMass = 1.0f / m_angularMass;
}
if (data.step.warmStarting)
{
// Scale impulses to support a variable time step.
m_linearImpulse *= data.step.dtRatio;
m_angularImpulse *= data.step.dtRatio;
b2Vec2 P = new b2Vec2(m_linearImpulse.x, m_linearImpulse.y);
vA -= mA * P;
wA -= iA * (b2Math.b2Cross(m_rA, P) + m_angularImpulse);
vB += mB * P;
wB += iB * (b2Math.b2Cross(m_rB, P) + m_angularImpulse);
}
else
{
m_linearImpulse.SetZero();
m_angularImpulse = 0.0f;
}
m_bodyA.InternalVelocity.v = vA;
m_bodyA.InternalVelocity.w = wA;
m_bodyB.InternalVelocity.v = vB;
m_bodyB.InternalVelocity.w = wB;
}
public override void InitVelocityConstraints(b2SolverData data)
{
m_indexA = m_bodyA.IslandIndex;
m_indexB = m_bodyB.IslandIndex;
m_localCenterA = m_bodyA.Sweep.localCenter;
m_localCenterB = m_bodyB.Sweep.localCenter;
m_invMassA = m_bodyA.InvertedMass;
m_invMassB = m_bodyB.InvertedMass;
m_invIA = m_bodyA.InvertedI;
m_invIB = m_bodyB.InvertedI;
b2Vec2 cA = m_bodyA.InternalPosition.c;
float aA = m_bodyA.InternalPosition.a;
b2Vec2 vA = m_bodyA.InternalVelocity.v;
float wA = m_bodyA.InternalVelocity.w;
b2Vec2 cB = m_bodyB.InternalPosition.c;
float aB = m_bodyB.InternalPosition.a;
b2Vec2 vB = m_bodyB.InternalVelocity.v;
float wB = m_bodyB.InternalVelocity.w;
b2Rot qA = new b2Rot(aA);
b2Rot qB = new b2Rot(aB);
m_rA = b2Math.b2Mul(qA, m_localAnchorA - m_localCenterA);
m_rB = b2Math.b2Mul(qB, m_localAnchorB - m_localCenterB);
m_u = cB + m_rB - cA - m_rA;
// Handle singularity.
float length = m_u.Length;
if (length > b2Settings.b2_linearSlop)
{
m_u *= 1.0f / length;
}
else
{
m_u.Set(0.0f, 0.0f);
}
float crAu = b2Math.b2Cross(ref m_rA, ref m_u);
float crBu = b2Math.b2Cross(ref m_rB, ref m_u);
float invMass = m_invMassA + m_invIA * crAu * crAu + m_invMassB + m_invIB * crBu * crBu;
// Compute the effective mass matrix.
m_mass = invMass != 0.0f ? 1.0f / invMass : 0.0f;
if (m_frequencyHz > 0.0f)
{
float C = length - m_length;
// Frequency
float omega = 2.0f * (float)Math.PI * m_frequencyHz;
// Damping coefficient
float d = 2.0f * m_mass * m_dampingRatio * omega;
// Spring stiffness
float k = m_mass * omega * omega;
// magic formulas
float h = data.step.dt;
m_gamma = h * (d + h * k);
m_gamma = m_gamma != 0.0f ? 1.0f / m_gamma : 0.0f;
m_bias = C * h * k * m_gamma;
invMass += m_gamma;
m_mass = invMass != 0.0f ? 1.0f / invMass : 0.0f;
}
else
{
m_gamma = 0.0f;
m_bias = 0.0f;
}
if (data.step.warmStarting)
{
// Scale the impulse to support a variable time step.
m_impulse *= data.step.dtRatio;
b2Vec2 P = m_impulse * m_u;
vA -= m_invMassA * P;
wA -= m_invIA * b2Math.b2Cross(ref m_rA, ref P);
vB += m_invMassB * P;
wB += m_invIB * b2Math.b2Cross(ref m_rB, ref P);
}
else
{
m_impulse = 0.0f;
}
m_bodyA.InternalVelocity.v = vA;
m_bodyA.InternalVelocity.w = wA;
m_bodyB.InternalVelocity.v = vB;
m_bodyB.InternalVelocity.w = wB;
}
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 void InitVelocityConstraints(b2SolverData data)
{
m_indexA = m_bodyA.IslandIndex;
m_indexB = m_bodyB.IslandIndex;
m_indexC = m_bodyC.IslandIndex;
m_indexD = m_bodyD.IslandIndex;
m_lcA = m_bodyA.Sweep.localCenter;
m_lcB = m_bodyB.Sweep.localCenter;
m_lcC = m_bodyC.Sweep.localCenter;
m_lcD = m_bodyD.Sweep.localCenter;
m_mA = m_bodyA.InvertedMass;
m_mB = m_bodyB.InvertedMass;
m_mC = m_bodyC.InvertedMass;
m_mD = m_bodyD.InvertedMass;
m_iA = m_bodyA.InvertedI;
m_iB = m_bodyB.InvertedI;
m_iC = m_bodyC.InvertedI;
m_iD = m_bodyD.InvertedI;
b2Vec2 cA = data.positions[m_indexA].c;
float aA = data.positions[m_indexA].a;
b2Vec2 vA = data.velocities[m_indexA].v;
float wA = data.velocities[m_indexA].w;
b2Vec2 cB = data.positions[m_indexB].c;
float aB = data.positions[m_indexB].a;
b2Vec2 vB = data.velocities[m_indexB].v;
float wB = data.velocities[m_indexB].w;
b2Vec2 cC = data.positions[m_indexC].c;
float aC = data.positions[m_indexC].a;
b2Vec2 vC = data.velocities[m_indexC].v;
float wC = data.velocities[m_indexC].w;
b2Vec2 cD = data.positions[m_indexD].c;
float aD = data.positions[m_indexD].a;
b2Vec2 vD = data.velocities[m_indexD].v;
float wD = data.velocities[m_indexD].w;
b2Rot qA = new b2Rot(aA);
b2Rot qB = new b2Rot(aB);
b2Rot qC = new b2Rot(aC);
b2Rot qD = new b2Rot(aD);
m_mass = 0.0f;
if (m_typeA == b2JointType.e_revoluteJoint)
{
m_JvAC.SetZero();
m_JwA = 1.0f;
m_JwC = 1.0f;
m_mass += m_iA + m_iC;
}
else
{
b2Vec2 u = b2Math.b2Mul(qC, m_localAxisC);
b2Vec2 rC = b2Math.b2Mul(qC, m_localAnchorC - m_lcC);
b2Vec2 rA = b2Math.b2Mul(qA, m_localAnchorA - m_lcA);
m_JvAC = u;
m_JwC = b2Math.b2Cross(rC, u);
m_JwA = b2Math.b2Cross(rA, u);
m_mass += m_mC + m_mA + m_iC * m_JwC * m_JwC + m_iA * m_JwA * m_JwA;
}
if (m_typeB == b2JointType.e_revoluteJoint)
{
m_JvBD.SetZero();
m_JwB = m_ratio;
m_JwD = m_ratio;
m_mass += m_ratio * m_ratio * (m_iB + m_iD);
}
else
{
b2Vec2 u = b2Math.b2Mul(qD, m_localAxisD);
b2Vec2 rD = b2Math.b2Mul(qD, m_localAnchorD - m_lcD);
b2Vec2 rB = b2Math.b2Mul(qB, m_localAnchorB - m_lcB);
m_JvBD = m_ratio * u;
m_JwD = m_ratio * b2Math.b2Cross(rD, u);
m_JwB = m_ratio * b2Math.b2Cross(rB, u);
m_mass += m_ratio * m_ratio * (m_mD + m_mB) + m_iD * m_JwD * m_JwD + m_iB * m_JwB * m_JwB;
}
// Compute effective mass.
m_mass = m_mass > 0.0f ? 1.0f / m_mass : 0.0f;
if (data.step.warmStarting)
{
vA += (m_mA * m_impulse) * m_JvAC;
wA += m_iA * m_impulse * m_JwA;
vB += (m_mB * m_impulse) * m_JvBD;
wB += m_iB * m_impulse * m_JwB;
vC -= (m_mC * m_impulse) * m_JvAC;
wC -= m_iC * m_impulse * m_JwC;
vD -= (m_mD * m_impulse) * m_JvBD;
wD -= m_iD * m_impulse * m_JwD;
}
else
{
m_impulse = 0.0f;
}
data.velocities[m_indexA].v = vA;
data.velocities[m_indexA].w = wA;
data.velocities[m_indexB].v = vB;
data.velocities[m_indexB].w = wB;
data.velocities[m_indexC].v = vC;
data.velocities[m_indexC].w = wC;
data.velocities[m_indexD].v = vD;
data.velocities[m_indexD].w = wD;
}