internal override bool SolvePositionConstraints(float baumgarte)
{
if (_frequencyHz > 0.0f)
{
// There is no position correction for soft distance constraints.
return(true);
}
Body b1 = _bodyA;
Body b2 = _bodyB;
Transform xf1, xf2;
b1.GetTransform(out xf1);
b2.GetTransform(out xf2);
Vector2 r1 = MathUtils.Multiply(ref xf1.R, _localAnchor1 - b1.GetLocalCenter());
Vector2 r2 = MathUtils.Multiply(ref xf2.R, _localAnchor2 - b2.GetLocalCenter());
Vector2 d = b2._sweep.c + r2 - b1._sweep.c - r1;
float length = d.magnitude;
if (length < _length)
{
return(true);
}
if (length == 0.0f)
{
return(true);
}
d /= length;
float C = length - _length;
C = MathUtils.Clamp(C, -Settings.b2_maxLinearCorrection, Settings.b2_maxLinearCorrection);
float impulse = -_mass * C;
_u = d;
Vector2 P = impulse * _u;
b1._sweep.c -= b1._invMass * P;
b1._sweep.a -= b1._invI * MathUtils.Cross(r1, P);
b2._sweep.c += b2._invMass * P;
b2._sweep.a += b2._invI * MathUtils.Cross(r2, P);
b1.SynchronizeTransform();
b2.SynchronizeTransform();
return(Math.Abs(C) < Settings.b2_linearSlop);
}
internal override bool SolvePositionConstraints(float baumgarte)
{
float linearError = 0.0f;
Body b1 = _bodyA;
Body b2 = _bodyB;
float coordinate1, coordinate2;
if (_revolute1 != null)
{
coordinate1 = _revolute1.GetJointAngle();
}
else
{
coordinate1 = _prismatic1.GetJointTranslation();
}
if (_revolute2 != null)
{
coordinate2 = _revolute2.GetJointAngle();
}
else
{
coordinate2 = _prismatic2.GetJointTranslation();
}
float C = _ant - (coordinate1 + _ratio * coordinate2);
float impulse = _mass * (-C);
b1._sweep.c += b1._invMass * impulse * _J.linearA;
b1._sweep.a += b1._invI * impulse * _J.angularA;
b2._sweep.c += b2._invMass * impulse * _J.linearB;
b2._sweep.a += b2._invI * impulse * _J.angularB;
b1.SynchronizeTransform();
b2.SynchronizeTransform();
// TODO_ERIN not implemented
return(linearError < Settings.b2_linearSlop);
}
internal override bool SolvePositionConstraints(float baumgarte)
{
Body b1 = _bodyA;
Body b2 = _bodyB;
Vector2 c1 = b1._sweep.c;
float a1 = b1._sweep.a;
Vector2 c2 = b2._sweep.c;
float a2 = b2._sweep.a;
// Solve linear limit constraint.
float linearError = 0.0f, angularError = 0.0f;
bool active = false;
float C2 = 0.0f;
Mat22 R1 = new Mat22(a1);
Mat22 R2 = new Mat22(a2);
Vector2 r1 = MathUtils.Multiply(ref R1, _localAnchor1 - _localCenterA);
Vector2 r2 = MathUtils.Multiply(ref R2, _localAnchor2 - _localCenterB);
Vector2 d = c2 + r2 - c1 - r1;
if (_enableLimit)
{
_axis = MathUtils.Multiply(ref R1, _localxAxis1);
_a1 = MathUtils.Cross(d + r1, _axis);
_a2 = MathUtils.Cross(r2, _axis);
float translation = Vector2.Dot(_axis, d);
if (Math.Abs(_upperTranslation - _lowerTranslation) < 2.0f * Settings.b2_linearSlop)
{
// Prevent large angular corrections
C2 = MathUtils.Clamp(translation, -Settings.b2_maxLinearCorrection, Settings.b2_maxLinearCorrection);
linearError = Math.Abs(translation);
active = true;
}
else if (translation <= _lowerTranslation)
{
// Prevent large linear corrections and allow some slop.
C2 = MathUtils.Clamp(translation - _lowerTranslation + Settings.b2_linearSlop, -Settings.b2_maxLinearCorrection, 0.0f);
linearError = _lowerTranslation - translation;
active = true;
}
else if (translation >= _upperTranslation)
{
// Prevent large linear corrections and allow some slop.
C2 = MathUtils.Clamp(translation - _upperTranslation - Settings.b2_linearSlop, 0.0f, Settings.b2_maxLinearCorrection);
linearError = translation - _upperTranslation;
active = true;
}
}
_perp = MathUtils.Multiply(ref R1, _localyAxis1);
_s1 = MathUtils.Cross(d + r1, _perp);
_s2 = MathUtils.Cross(r2, _perp);
Vector3 impulse;
Vector2 C1 = new Vector2(Vector2.Dot(_perp, d), a2 - a1 - _refAngle);
linearError = Math.Max(linearError, Math.Abs(C1.x));
angularError = Math.Abs(C1.y);
if (active)
{
float m1 = _invMassA, m2 = _invMassB;
float i1 = _invIA, i2 = _invIB;
float k11 = m1 + m2 + i1 * _s1 * _s1 + i2 * _s2 * _s2;
float k12 = i1 * _s1 + i2 * _s2;
float k13 = i1 * _s1 * _a1 + i2 * _s2 * _a2;
float k22 = i1 + i2;
float k23 = i1 * _a1 + i2 * _a2;
float k33 = m1 + m2 + i1 * _a1 * _a1 + i2 * _a2 * _a2;
_K.col1 = new Vector3(k11, k12, k13);
_K.col2 = new Vector3(k12, k22, k23);
_K.col3 = new Vector3(k13, k23, k33);
Vector3 C = new Vector3(-C1.x, -C1.y, -C2);
impulse = _K.Solve33(C); // negated above
}
else
{
float m1 = _invMassA, m2 = _invMassB;
float i1 = _invIA, i2 = _invIB;
float k11 = m1 + m2 + i1 * _s1 * _s1 + i2 * _s2 * _s2;
float k12 = i1 * _s1 + i2 * _s2;
float k22 = i1 + i2;
_K.col1 = new Vector3(k11, k12, 0.0f);
_K.col2 = new Vector3(k12, k22, 0.0f);
Vector2 impulse1 = _K.Solve22(-C1);
impulse.x = impulse1.x;
impulse.y = impulse1.y;
impulse.z = 0.0f;
}
Vector2 P = impulse.x * _perp + impulse.z * _axis;
float L1 = impulse.x * _s1 + impulse.y + impulse.z * _a1;
float L2 = impulse.x * _s2 + impulse.y + impulse.z * _a2;
c1 -= _invMassA * P;
a1 -= _invIA * L1;
c2 += _invMassB * P;
a2 += _invIB * L2;
// TODO_ERIN remove need for this.
b1._sweep.c = c1;
b1._sweep.a = a1;
b2._sweep.c = c2;
b2._sweep.a = a2;
b1.SynchronizeTransform();
b2.SynchronizeTransform();
return(linearError <= Settings.b2_linearSlop && angularError <= Settings.b2_angularSlop);
}
public bool SolvePositionConstraints(float baumgarte)
{
float minSeparation = 0.0f;
for (int i = 0; i < _constraintCount; ++i)
{
ContactConstraint c = _constraints[i];
Body bodyA = c.bodyA;
Body bodyB = c.bodyB;
float invMassA = bodyA._mass * bodyA._invMass;
float invIA = bodyA._mass * bodyA._invI;
float invMassB = bodyB._mass * bodyB._invMass;
float invIB = bodyB._mass * bodyB._invI;
// Solve normal constraints
for (int j = 0; j < c.pointCount; ++j)
{
PositionSolverManifold psm = new PositionSolverManifold(ref c, j);
Vector2 normal = psm._normal;
Vector2 point = psm._point;
float separation = psm._separation;
Vector2 rA = point - bodyA._sweep.c;
Vector2 rB = point - bodyB._sweep.c;
// Track max constraint error.
minSeparation = Math.Min(minSeparation, separation);
// Prevent large corrections and allow slop.
float C = MathUtils.Clamp(baumgarte * (separation + Settings.b2_linearSlop), -Settings.b2_maxLinearCorrection, 0.0f);
// Compute the effective mass.
float rnA = MathUtils.Cross(rA, normal);
float rnB = MathUtils.Cross(rB, normal);
float K = invMassA + invMassB + invIA * rnA * rnA + invIB * rnB * rnB;
// Compute normal impulse
float impulse = K > 0.0f ? -C / K : 0.0f;
#if MATH_OVERLOADS
Vector2 P = impulse * normal;
bodyA._sweep.c -= invMassA * P;
bodyA._sweep.a -= invIA * MathUtils.Cross(rA, P);
bodyB._sweep.c += invMassB * P;
bodyB._sweep.a += invIB * MathUtils.Cross(rB, P);
#else
Vector2 P = new Vector2(impulse * normal.x, impulse * normal.y);
bodyA._sweep.c.x -= invMassA * P.x;
bodyA._sweep.c.y -= invMassA * P.y;
bodyA._sweep.a -= invIA * (rA.x * P.y - rA.y * P.x);
bodyB._sweep.c.x += invMassB * P.x;
bodyB._sweep.c.y += invMassB * P.y;
bodyB._sweep.a += invIB * (rB.x * P.y - rB.y * P.x);
#endif
bodyA.SynchronizeTransform();
bodyB.SynchronizeTransform();
}
}
// We can't expect minSpeparation >= -Settings.b2_linearSlop because we don't
// push the separation above -Settings.b2_linearSlop.
return(minSeparation >= -1.5f * Settings.b2_linearSlop);
}
internal override bool SolvePositionConstraints(float baumgarte)
{
// TODO_ERIN block solve with limit. COME ON ERIN
Body b1 = _bodyA;
Body b2 = _bodyB;
float angularError = 0.0f;
float positionError = 0.0f;
// Solve angular limit constraint.
if (_enableLimit && _limitState != LimitState.Inactive)
{
float angle = b2._sweep.a - b1._sweep.a - _referenceAngle;
float limitImpulse = 0.0f;
if (_limitState == LimitState.Equal)
{
// Prevent large angular corrections
float C = MathUtils.Clamp(angle - _lowerAngle, -Settings.b2_maxAngularCorrection, Settings.b2_maxAngularCorrection);
limitImpulse = -_motorMass * C;
angularError = Math.Abs(C);
}
else if (_limitState == LimitState.AtLower)
{
float C = angle - _lowerAngle;
angularError = -C;
// Prevent large angular corrections and allow some slop.
C = MathUtils.Clamp(C + Settings.b2_angularSlop, -Settings.b2_maxAngularCorrection, 0.0f);
limitImpulse = -_motorMass * C;
}
else if (_limitState == LimitState.AtUpper)
{
float C = angle - _upperAngle;
angularError = C;
// Prevent large angular corrections and allow some slop.
C = MathUtils.Clamp(C - Settings.b2_angularSlop, 0.0f, Settings.b2_maxAngularCorrection);
limitImpulse = -_motorMass * C;
}
b1._sweep.a -= b1._invI * limitImpulse;
b2._sweep.a += b2._invI * limitImpulse;
b1.SynchronizeTransform();
b2.SynchronizeTransform();
}
// Solve point-to-point constraint.
{
Transform xf1, xf2;
b1.GetTransform(out xf1);
b2.GetTransform(out xf2);
Vector2 r1 = MathUtils.Multiply(ref xf1.R, _localAnchor1 - b1.GetLocalCenter());
Vector2 r2 = MathUtils.Multiply(ref xf2.R, _localAnchor2 - b2.GetLocalCenter());
Vector2 C = b2._sweep.c + r2 - b1._sweep.c - r1;
positionError = C.magnitude;
float invMass1 = b1._invMass, invMass2 = b2._invMass;
float invI1 = b1._invI, invI2 = b2._invI;
// Handle large detachment.
const float k_allowedStretch = 10.0f * Settings.b2_linearSlop;
if (C.sqrMagnitude > k_allowedStretch * k_allowedStretch)
{
// Use a particle solution (no rotation).
Vector2 u = C; u.Normalize();
float k = invMass1 + invMass2;
//Debug.Assert(k > Settings.b2_epsilon);
float m = 1.0f / k;
Vector2 impulse2 = m * (-C);
const float k_beta = 0.5f;
b1._sweep.c -= k_beta * invMass1 * impulse2;
b2._sweep.c += k_beta * invMass2 * impulse2;
C = b2._sweep.c + r2 - b1._sweep.c - r1;
}
Mat22 K1 = new Mat22(new Vector2(invMass1 + invMass2, 0.0f), new Vector2(0.0f, invMass1 + invMass2));
Mat22 K2 = new Mat22(new Vector2(invI1 * r1.y * r1.y, -invI1 * r1.x * r1.y), new Vector2(-invI1 * r1.x * r1.y, invI1 * r1.x * r1.x));
Mat22 K3 = new Mat22(new Vector2(invI2 * r2.y * r2.y, -invI2 * r2.x * r2.y), new Vector2(-invI2 * r2.x * r2.y, invI2 * r2.x * r2.x));
Mat22 Ka;
Mat22 K;
Mat22.Add(ref K1, ref K2, out Ka);
Mat22.Add(ref Ka, ref K3, out K);
Vector2 impulse = K.Solve(-C);
b1._sweep.c -= b1._invMass * impulse;
b1._sweep.a -= b1._invI * MathUtils.Cross(r1, impulse);
b2._sweep.c += b2._invMass * impulse;
b2._sweep.a += b2._invI * MathUtils.Cross(r2, impulse);
b1.SynchronizeTransform();
b2.SynchronizeTransform();
}
return(positionError <= Settings.b2_linearSlop && angularError <= Settings.b2_angularSlop);
}
internal override bool SolvePositionConstraints(float baumgarte)
{
Body b1 = _bodyA;
Body b2 = _bodyB;
Vector2 s1 = _groundAnchor1;
Vector2 s2 = _groundAnchor2;
float linearError = 0.0f;
if (_state == LimitState.AtUpper)
{
Transform xf1, xf2;
b1.GetTransform(out xf1);
b2.GetTransform(out xf2);
Vector2 r1 = MathUtils.Multiply(ref xf1.R, _localAnchor1 - b1.GetLocalCenter());
Vector2 r2 = MathUtils.Multiply(ref xf2.R, _localAnchor2 - b2.GetLocalCenter());
Vector2 p1 = b1._sweep.c + r1;
Vector2 p2 = b2._sweep.c + r2;
// Get the pulley axes.
_u1 = p1 - s1;
_u2 = p2 - s2;
float length1 = _u1.magnitude;
float length2 = _u2.magnitude;
if (length1 > Settings.b2_linearSlop)
{
_u1 *= 1.0f / length1;
}
else
{
_u1 = Vector2.zero;
}
if (length2 > Settings.b2_linearSlop)
{
_u2 *= 1.0f / length2;
}
else
{
_u2 = Vector2.zero;
}
float C = _ant - length1 - _ratio * length2;
linearError = Math.Max(linearError, -C);
C = MathUtils.Clamp(C + Settings.b2_linearSlop, -Settings.b2_maxLinearCorrection, 0.0f);
float impulse = -_pulleyMass * C;
Vector2 P1 = -impulse * _u1;
Vector2 P2 = -_ratio * impulse * _u2;
b1._sweep.c += b1._invMass * P1;
b1._sweep.a += b1._invI * MathUtils.Cross(r1, P1);
b2._sweep.c += b2._invMass * P2;
b2._sweep.a += b2._invI * MathUtils.Cross(r2, P2);
b1.SynchronizeTransform();
b2.SynchronizeTransform();
}
if (_limitState1 == LimitState.AtUpper)
{
Transform xf1;
b1.GetTransform(out xf1);
Vector2 r1 = MathUtils.Multiply(ref xf1.R, _localAnchor1 - b1.GetLocalCenter());
Vector2 p1 = b1._sweep.c + r1;
_u1 = p1 - s1;
float length1 = _u1.magnitude;
if (length1 > Settings.b2_linearSlop)
{
_u1 *= 1.0f / length1;
}
else
{
_u1 = Vector2.zero;
}
float C = _maxLength1 - length1;
linearError = Math.Max(linearError, -C);
C = MathUtils.Clamp(C + Settings.b2_linearSlop, -Settings.b2_maxLinearCorrection, 0.0f);
float impulse = -_limitMass1 * C;
Vector2 P1 = -impulse * _u1;
b1._sweep.c += b1._invMass * P1;
b1._sweep.a += b1._invI * MathUtils.Cross(r1, P1);
b1.SynchronizeTransform();
}
if (_limitState2 == LimitState.AtUpper)
{
Transform xf2;
b2.GetTransform(out xf2);
Vector2 r2 = MathUtils.Multiply(ref xf2.R, _localAnchor2 - b2.GetLocalCenter());
Vector2 p2 = b2._sweep.c + r2;
_u2 = p2 - s2;
float length2 = _u2.magnitude;
if (length2 > Settings.b2_linearSlop)
{
_u2 *= 1.0f / length2;
}
else
{
_u2 = Vector2.zero;
}
float C = _maxLength2 - length2;
linearError = Math.Max(linearError, -C);
C = MathUtils.Clamp(C + Settings.b2_linearSlop, -Settings.b2_maxLinearCorrection, 0.0f);
float impulse = -_limitMass2 * C;
Vector2 P2 = -impulse * _u2;
b2._sweep.c += b2._invMass * P2;
b2._sweep.a += b2._invI * MathUtils.Cross(r2, P2);
b2.SynchronizeTransform();
}
return(linearError < Settings.b2_linearSlop);
}
public void Solve(Profile profile, TimeStep step, Vec2 gravity, bool allowSleep)
{
Timer timer = new Timer();
float h = step.dt;
// Integrate velocities and apply damping. Initialize the body state.
for (int i = 0; i < m_bodies.Count(); i++)
{
Body b = m_bodies[i];
Vec2 c = b.m_sweep.c;
float a = b.m_sweep.a;
Vec2 v = b.m_linearVelocity;
float w = b.m_angularVelocity;
// Store positions for continuous collision.
b.m_sweep.c0 = b.m_sweep.c;
b.m_sweep.a0 = b.m_sweep.a;
if (b.m_type == BodyType._dynamicBody)
{
// Integrate velocities.
v += h * (b.m_gravityScale * gravity + b.m_invMass * b.m_force);
w += h * b.m_invI * b.m_torque;
// Apply damping.
// ODE: dv/dt + c * v = 0
// Solution: v(t) = v0 * exp(-c * t)
// Time step: v(t + dt) = v0 * exp(-c * (t + dt)) = v0 * exp(-c * t) * exp(-c * dt) = v * exp(-c * dt)
// v2 = exp(-c * dt) * v1
// Taylor expansion:
// v2 = (1.0f - c * dt) * v1
v *= Utilities.Clamp(1.0f - h * b.m_linearDamping, 0.0f, 1.0f);
w *= Utilities.Clamp(1.0f - h * b.m_angularDamping, 0.0f, 1.0f);
}
Position pos = new Position();
pos.c = c;
pos.a = a;
m_positions.Add(pos);
Velocity vel = new Velocity();
vel.v = v;
vel.w = w;
m_velocities.Add(vel);
}
timer.Reset();
// Solver data
SolverData solverData;
solverData.step = step;
solverData.positions = m_positions;
solverData.velocities = m_velocities;
// Initialize velocity constraints.
ContactSolverDef contactSolverDef;
contactSolverDef.step = step;
contactSolverDef.contacts = m_contacts;
contactSolverDef.positions = m_positions;
contactSolverDef.velocities = m_velocities;
ContactSolver contactSolver = new ContactSolver(contactSolverDef);
contactSolver.InitializeVelocityConstraints();
if (step.warmStarting)
{
contactSolver.WarmStart();
}
for (int i = 0; i < m_joints.Count(); ++i)
{
m_joints[i].InitVelocityConstraints(solverData);
}
profile.solveInit = timer.GetMilliseconds();
// Solve velocity constraints
timer.Reset();
for (int i = 0; i < step.velocityIterations; ++i)
{
for (int j = 0; j < m_joints.Count(); ++j)
{
m_joints[j].SolveVelocityConstraints(solverData);
}
contactSolver.SolveVelocityConstraints();
}
// Store impulses for warm starting
contactSolver.StoreImpulses();
profile.solveVelocity = timer.GetMilliseconds();
// Integrate positions
for (int i = 0; i < m_bodies.Count(); ++i)
{
Vec2 c = m_positions[i].c;
float a = m_positions[i].a;
Vec2 v = m_velocities[i].v;
float w = m_velocities[i].w;
// Check for large velocities
Vec2 translation = h * v;
if (Utilities.Dot(translation, translation) > Settings._maxTranslationSquared)
{
float ratio = Settings._maxTranslation / translation.Length();
v *= ratio;
}
float rotation = h * w;
if (rotation * rotation > Settings._maxRotationSquared)
{
float ratio = Settings._maxRotation / Math.Abs(rotation);
w *= ratio;
}
// Integrate
c += h * v;
a += h * w;
m_positions[i].c = c;
m_positions[i].a = a;
m_velocities[i].v = v;
m_velocities[i].w = w;
}
// Solve position constraints
timer.Reset();
bool positionSolved = false;
for (int i = 0; i < step.positionIterations; ++i)
{
bool contactsOkay = contactSolver.SolvePositionConstraints();
bool jointsOkay = true;
for (int j = 0; j < m_joints.Count; ++j)
{
bool jointOkay = m_joints[j].SolvePositionConstraints(solverData);
jointsOkay = jointsOkay && jointOkay;
}
if (contactsOkay && jointsOkay)
{
// Exit early if the position errors are small.
positionSolved = true;
break;
}
}
// Copy state buffers back to the bodies
for (int i = 0; i < m_bodies.Count(); ++i)
{
Body body = m_bodies[i];
body.m_sweep.c = m_positions[i].c;
body.m_sweep.a = m_positions[i].a;
body.m_linearVelocity = m_velocities[i].v;
body.m_angularVelocity = m_velocities[i].w;
body.SynchronizeTransform();
}
profile.solvePosition = timer.GetMilliseconds();
Report(contactSolver.m_velocityConstraints);
if (allowSleep)
{
float minSleepTime = Single.MaxValue;
const float linTolSqr = Settings._linearSleepTolerance * Settings._linearSleepTolerance;
const float angTolSqr = Settings._angularSleepTolerance * Settings._angularSleepTolerance;
for (int i = 0; i < m_bodies.Count(); ++i)
{
Body b = m_bodies[i];
if (b.GetBodyType() == BodyType._staticBody)
{
continue;
}
if ((b.m_flags & Body.BodyFlags.e_autoSleepFlag) == 0 ||
b.m_angularVelocity * b.m_angularVelocity > angTolSqr ||
Utilities.Dot(b.m_linearVelocity, b.m_linearVelocity) > linTolSqr)
{
b.m_sleepTime = 0.0f;
minSleepTime = 0.0f;
}
else
{
b.m_sleepTime += h;
minSleepTime = Math.Min(minSleepTime, b.m_sleepTime);
}
}
if (minSleepTime >= Settings._timeToSleep && positionSolved)
{
for (int i = 0; i < m_bodies.Count(); ++i)
{
Body b = m_bodies[i];
b.SetAwake(false);
}
}
}
}
public void Solve(ref TimeStep step, Vector2 gravity, bool allowSleep)
{
// Integrate velocities and apply damping.
for (int i = 0; i < _bodyCount; ++i)
{
Body b = _bodies[i];
if (b.GetType() != BodyType.Dynamic)
{
continue;
}
// Integrate velocities.
b._linearVelocity += step.dt * (gravity + b._invMass * b._force);
b._angularVelocity += step.dt * b._invI * b._torque;
// Apply damping.
// ODE: dv/dt + c * v = 0
// Solution: v(t) = v0 * exp(-c * t)
// Time step: v(t + dt) = v0 * exp(-c * (t + dt)) = v0 * exp(-c * t) * exp(-c * dt) = v * exp(-c * dt)
// v2 = exp(-c * dt) * v1
// Taylor expansion:
// v2 = (1.0f - c * dt) * v1
b._linearVelocity *= MathUtils.Clamp(1.0f - step.dt * b._linearDamping, 0.0f, 1.0f);
b._angularVelocity *= MathUtils.Clamp(1.0f - step.dt * b._angularDamping, 0.0f, 1.0f);
}
// Partition contacts so that contacts with static bodies are solved last.
int i1 = -1;
for (int i2 = 0; i2 < _contactCount; ++i2)
{
Fixture fixtureA = _contacts[i2].GetFixtureA();
Fixture fixtureB = _contacts[i2].GetFixtureB();
Body bodyA = fixtureA.GetBody();
Body bodyB = fixtureB.GetBody();
bool nonStatic = bodyA.GetType() != BodyType.Static && bodyB.GetType() != BodyType.Static;
if (nonStatic)
{
++i1;
//b2Swap(_contacts[i1], _contacts[i2]);
Contact temp = _contacts[i1];
_contacts[i1] = _contacts[i2];
_contacts[i2] = temp;
}
}
// Initialize velocity constraints.
_contactSolver.Reset(_contacts, _contactCount, step.dtRatio);
_contactSolver.WarmStart();
for (int i = 0; i < _jointCount; ++i)
{
_joints[i].InitVelocityConstraints(ref step);
}
// Solve velocity constraints.
for (int i = 0; i < step.velocityIterations; ++i)
{
for (int j = 0; j < _jointCount; ++j)
{
_joints[j].SolveVelocityConstraints(ref step);
}
_contactSolver.SolveVelocityConstraints();
}
// Post-solve (store impulses for warm starting).
_contactSolver.StoreImpulses();
// Integrate positions.
for (int i = 0; i < _bodyCount; ++i)
{
Body b = _bodies[i];
if (b.GetType() == BodyType.Static)
{
continue;
}
// Check for large velocities.
Vector2 translation = step.dt * b._linearVelocity;
if (Vector2.Dot(translation, translation) > Settings.b2_maxTranslationSquared)
{
float ratio = Settings.b2_maxTranslation / translation.magnitude;
b._linearVelocity *= ratio;
}
float rotation = step.dt * b._angularVelocity;
if (rotation * rotation > Settings.b2_maxRotationSquared)
{
float ratio = Settings.b2_maxRotation / Math.Abs(rotation);
b._angularVelocity *= ratio;
}
// Store positions for continuous collision.
b._sweep.c0 = b._sweep.c;
b._sweep.a0 = b._sweep.a;
// Integrate
b._sweep.c += step.dt * b._linearVelocity;
b._sweep.a += step.dt * b._angularVelocity;
// Compute new transform
b.SynchronizeTransform();
// Note: shapes are synchronized later.
}
// Iterate over constraints.
for (int i = 0; i < step.positionIterations; ++i)
{
bool contactsOkay = _contactSolver.SolvePositionConstraints(Settings.b2_contactBaumgarte);
bool jointsOkay = true;
for (int j = 0; j < _jointCount; ++j)
{
bool jointOkay = _joints[j].SolvePositionConstraints(Settings.b2_contactBaumgarte);
jointsOkay = jointsOkay && jointOkay;
}
if (contactsOkay && jointsOkay)
{
// Exit early if the position errors are small.
break;
}
}
Report(_contactSolver._constraints);
if (allowSleep)
{
float minSleepTime = Settings.b2_maxFloat;
const float linTolSqr = Settings.b2_linearSleepTolerance * Settings.b2_linearSleepTolerance;
const float angTolSqr = Settings.b2_angularSleepTolerance * Settings.b2_angularSleepTolerance;
for (int i = 0; i < _bodyCount; ++i)
{
Body b = _bodies[i];
if (b.GetType() == BodyType.Static)
{
continue;
}
if ((b._flags & BodyFlags.AutoSleep) == 0)
{
b._sleepTime = 0.0f;
minSleepTime = 0.0f;
}
if ((b._flags & BodyFlags.AutoSleep) == 0 ||
b._angularVelocity * b._angularVelocity > angTolSqr ||
Vector2.Dot(b._linearVelocity, b._linearVelocity) > linTolSqr)
{
b._sleepTime = 0.0f;
minSleepTime = 0.0f;
}
else
{
b._sleepTime += step.dt;
minSleepTime = Math.Min(minSleepTime, b._sleepTime);
}
}
if (minSleepTime >= Settings.b2_timeToSleep)
{
for (int i = 0; i < _bodyCount; ++i)
{
Body b = _bodies[i];
b.SetAwake(false);
}
}
}
}
private void SolveTOI(TimeStep step)
{
Island island = new Island(m_contactManager.m_contactListener);
if (m_stepComplete)
{
foreach (Body b in m_bodyList)
{
b.m_flags &= ~Body.BodyFlags.e_islandFlag;
b.m_sweep.alpha0 = 0.0f;
}
foreach (Contact c in m_contactManager.m_contactList)
{
// Invalidate TOI
c.m_flags &= ~(ContactFlags.e_toiFlag | ContactFlags.e_islandFlag);
c.m_toiCount = 0;
c.m_toi = 1.0f;
}
}
Fixture fA = null;
Fixture fB = null;
Body bA = null;
Body bB = null;
// Find TOI events and solve them.
for (;;)
{
// Find the first TOI.
Contact minContact = null;
float minAlpha = 1.0f;
foreach (Contact c in m_contactManager.m_contactList)
{
// Is this contact disabled?
if (c.IsEnabled() == false)
{
continue;
}
// Prevent excessive sub-stepping.
if (c.m_toiCount > Settings._maxSubSteps)
{
continue;
}
float alpha = 1.0f;
if (c.m_flags.HasFlag(ContactFlags.e_toiFlag))
{
// This contact has a valid cached TOI.
alpha = c.m_toi;
}
else
{
fA = c.FixtureA;
fB = c.FixtureB;
// Is there a sensor?
if (fA.IsSensor || fB.IsSensor)
{
continue;
}
bA = fA.GetBody();
bB = fB.GetBody();
BodyType typeA = bA.m_type;
BodyType typeB = bB.m_type;
Utilities.Assert(typeA == BodyType._dynamicBody || typeB == BodyType._dynamicBody);
bool activeA = bA.IsAwake() && typeA != BodyType._staticBody;
bool activeB = bB.IsAwake() && typeB != BodyType._staticBody;
// Is at least one body active (awake and dynamic or kinematic)?
if (activeA == false && activeB == false)
{
continue;
}
bool collideA = bA.IsBullet() || typeA != BodyType._dynamicBody;
bool collideB = bB.IsBullet() || typeB != BodyType._dynamicBody;
// Are these two non-bullet dynamic bodies?
if (collideA == false && collideB == false)
{
continue;
}
// Compute the TOI for this contact.
// Put the sweeps onto the same time interval.
float alpha0 = bA.m_sweep.alpha0;
if (bA.m_sweep.alpha0 < bB.m_sweep.alpha0)
{
alpha0 = bB.m_sweep.alpha0;
bA.m_sweep.Advance(alpha0);
}
else if (bB.m_sweep.alpha0 < bA.m_sweep.alpha0)
{
alpha0 = bA.m_sweep.alpha0;
bB.m_sweep.Advance(alpha0);
}
Utilities.Assert(alpha0 < 1.0f);
int indexA = c.GetChildIndexA();
int indexB = c.GetChildIndexB();
// Compute the time of impact in interval [0, minTOI]
TOIInput input = new TOIInput();
input.proxyA.Set(fA.GetShape(), indexA);
input.proxyB.Set(fB.GetShape(), indexB);
input.sweepA = bA.m_sweep;
input.sweepB = bB.m_sweep;
input.tMax = 1.0f;
TOIOutput output;
Utilities.TimeOfImpact(out output, input);
// Beta is the fraction of the remaining portion of the .
float beta = output.t;
if (output.state == TOIOutput.State.e_touching)
{
alpha = Math.Min(alpha0 + (1.0f - alpha0) * beta, 1.0f);
}
else
{
alpha = 1.0f;
}
c.m_toi = alpha;
c.m_flags |= ContactFlags.e_toiFlag;
}
if (alpha < minAlpha)
{
// This is the minimum TOI found so far.
minContact = c;
minAlpha = alpha;
}
}
if (minContact == null || 1.0f - 10.0f * Single.Epsilon < minAlpha)
{
// No more TOI events. Done!
m_stepComplete = true;
break;
}
// Advance the bodies to the TOI.
fA = minContact.FixtureA;
fB = minContact.FixtureB;
bA = fA.GetBody();
bB = fB.GetBody();
Sweep backup1 = bA.m_sweep;
Sweep backup2 = bB.m_sweep;
bA.Advance(minAlpha);
bB.Advance(minAlpha);
// The TOI contact likely has some new contact points.
minContact.Update(m_contactManager.m_contactListener);
minContact.m_flags &= ~ContactFlags.e_toiFlag;
++minContact.m_toiCount;
// Is the contact solid?
if (minContact.IsEnabled() == false || minContact.IsTouching() == false)
{
// Restore the sweeps.
minContact.SetEnabled(false);
bA.m_sweep = backup1;
bB.m_sweep = backup2;
bA.SynchronizeTransform();
bB.SynchronizeTransform();
continue;
}
bA.SetAwake(true);
bB.SetAwake(true);
// Build the island
island.Clear();
island.Add(bA);
island.Add(bB);
island.Add(minContact);
bA.m_flags |= Body.BodyFlags.e_islandFlag;
bB.m_flags |= Body.BodyFlags.e_islandFlag;
minContact.m_flags |= ContactFlags.e_islandFlag;
// Get contacts on bodyA and bodyB.
Body[] bodies = { bA, bB };
for (int i = 0; i < 2; ++i)
{
Body body = bodies[i];
if (body.m_type == BodyType._dynamicBody)
{
foreach (ContactEdge ce in body.m_contactList)
{
throw new NotImplementedException();
//if (island.m_bodies.Count() == island.m_bodyCapacity)
//{
// break;
//}
//if (island.m_bodies.Count() == island.m_contactCapacity)
//{
// break;
//}
//Contact* contact = ce.contact;
//// Has this contact already been added to the island?
//if (contact.m_flags & ContactFlags.e_islandFlag)
//{
// continue;
//}
//// Only add static, kinematic, or bullet bodies.
//Body* other = ce.other;
//if (other.m_type == _dynamicBody &&
// body.IsBullet() == false && other.IsBullet() == false)
//{
// continue;
//}
//// Skip sensors.
//bool sensorA = contact.m_fixtureA.m_isSensor;
//bool sensorB = contact.m_fixtureB.m_isSensor;
//if (sensorA || sensorB)
//{
// continue;
//}
//// Tentatively advance the body to the TOI.
//Sweep backup = other.m_sweep;
//if ((other.m_flags & Body.BodyFlags.e_islandFlag) == 0)
//{
// other.Advance(minAlpha);
//}
//// Update the contact points
//contact.Update(m_contactManager.m_contactListener);
//// Was the contact disabled by the user?
//if (contact.IsEnabled() == false)
//{
// other.m_sweep = backup;
// other.SynchronizeTransform();
// continue;
//}
//// Are there contact points?
//if (contact.IsTouching() == false)
//{
// other.m_sweep = backup;
// other.SynchronizeTransform();
// continue;
//}
//// Add the contact to the island
//contact.m_flags |= ContactFlags.e_islandFlag;
//island.Add(contact);
//// Has the other body already been added to the island?
//if (other.m_flags & Body.BodyFlags.e_islandFlag)
//{
// continue;
//}
//// Add the other body to the island.
//other.m_flags |= Body.BodyFlags.e_islandFlag;
//if (other.m_type != _staticBody)
//{
// other.SetAwake(true);
//}
//island.Add(other);
}
}
}
TimeStep subStep;
subStep.dt = (1.0f - minAlpha) * step.dt;
subStep.inv_dt = 1.0f / subStep.dt;
subStep.dtRatio = 1.0f;
subStep.positionIterations = 20;
subStep.velocityIterations = step.velocityIterations;
subStep.warmStarting = false;
island.SolveTOI(subStep, bA.m_islandIndex, bB.m_islandIndex);
// Reset island flags and synchronize broad-phase proxies.
for (int i = 0; i < island.m_bodies.Count(); ++i)
{
throw new NotImplementedException();
//Body* body = island.m_bodies[i];
//body.m_flags &= ~Body.BodyFlags.e_islandFlag;
//if (body.m_type != _dynamicBody)
//{
// continue;
//}
//body.SynchronizeFixtures();
//// Invalidate all contact TOIs on this displaced body.
//for (ContactEdge* ce = body.m_contactList; ce; ce = ce.next)
//{
// ce.contact.m_flags &= ~(ContactFlags.e_toiFlag | ContactFlags.e_islandFlag);
//}
}
// Commit fixture proxy movements to the broad-phase so that new contacts are created.
// Also, some contacts can be destroyed.
m_contactManager.FindNewContacts();
if (m_subStepping)
{
m_stepComplete = false;
break;
}
}
}
// Perform one solver iteration. Returns true if converged.
public bool Solve(float baumgarte)
{
float minSeparation = 0.0f;
for (int i = 0; i < _count; ++i)
{
TOIConstraint c = _constraints[i];
Body bodyA = c.bodyA;
Body bodyB = c.bodyB;
float massA = bodyA._mass;
float massB = bodyB._mass;
// Only the TOI body should move.
if (bodyA == _toiBody)
{
massB = 0.0f;
}
else
{
massA = 0.0f;
}
float invMassA = massA * bodyA._invMass;
float invIA = massA * bodyA._invI;
float invMassB = massB * bodyB._invMass;
float invIB = massB * bodyB._invI;
// Solve normal constraints
for (int j = 0; j < c.pointCount; ++j)
{
TOISolverManifold psm = new TOISolverManifold(ref c, j);
Vector2 normal = psm.normal;
Vector2 point = psm.point;
float separation = psm.separation;
Vector2 rA = point - bodyA._sweep.c;
Vector2 rB = point - bodyB._sweep.c;
// Track max constraint error.
minSeparation = Math.Min(minSeparation, separation);
// Prevent large corrections and allow slop.
float C = MathUtils.Clamp(baumgarte * (separation + Settings.b2_linearSlop), -Settings.b2_maxLinearCorrection, 0.0f);
// Compute the effective mass.
float rnA = MathUtils.Cross(rA, normal);
float rnB = MathUtils.Cross(rB, normal);
float K = invMassA + invMassB + invIA * rnA * rnA + invIB * rnB * rnB;
// Compute normal impulse
float impulse = K > 0.0f ? -C / K : 0.0f;
Vector2 P = impulse * normal;
bodyA._sweep.c -= invMassA * P;
bodyA._sweep.a -= invIA * MathUtils.Cross(rA, P);
bodyA.SynchronizeTransform();
bodyB._sweep.c += invMassB * P;
bodyB._sweep.a += invIB * MathUtils.Cross(rB, P);
bodyB.SynchronizeTransform();
}
}
// We can't expect minSpeparation >= -b2_linearSlop because we don't
// push the separation above -b2_linearSlop.
return(minSeparation >= -1.5f * Settings.b2_linearSlop);
}
