/// Get the world manifold.
public void GetWorldManifold(out WorldManifold worldManifold)
{
Body bodyA = _fixtureA.GetBody();
Body bodyB = _fixtureB.GetBody();
Shape shapeA = _fixtureA.GetShape();
Shape shapeB = _fixtureB.GetShape();
XForm xfA, xfB;
bodyA.GetXForm(out xfA);
bodyA.GetXForm(out xfB);
worldManifold = new WorldManifold(ref _manifold, ref xfA, shapeA._radius, ref xfB, shapeB._radius);
}
/// Get the current joint translation speed, usually in meters per second.
public float GetJointSpeed()
{
Body b1 = _bodyA;
Body b2 = _bodyB;
XForm xf1, xf2;
b1.GetXForm(out xf1);
b2.GetXForm(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;
Vector2 d = p2 - p1;
Vector2 axis = b1.GetWorldVector(_localXAxis1);
Vector2 v1 = b1._linearVelocity;
Vector2 v2 = b2._linearVelocity;
float w1 = b1._angularVelocity;
float w2 = b2._angularVelocity;
float speed = Vector2.Dot(d, MathUtils.Cross(w1, axis)) + Vector2.Dot(axis, v2 + MathUtils.Cross(w2, r2) - v1 - MathUtils.Cross(w1, r1));
return(speed);
}
internal override void SolveVelocityConstraints(ref TimeStep step)
{
Body b1 = _bodyA;
Body b2 = _bodyB;
XForm xf1, xf2;
b1.GetXForm(out xf1);
b2.GetXForm(out xf2);
Vector2 r1 = MathUtils.Multiply(ref xf1.R, _localAnchor1 - b1.GetLocalCenter());
Vector2 r2 = MathUtils.Multiply(ref xf2.R, _localAnchor2 - b2.GetLocalCenter());
// Cdot = dot(u, v + cross(w, r))
Vector2 v1 = b1._linearVelocity + MathUtils.Cross(b1._angularVelocity, r1);
Vector2 v2 = b2._linearVelocity + MathUtils.Cross(b2._angularVelocity, r2);
float Cdot = Vector2.Dot(_u, v2 - v1);
float impulse = -_mass * (Cdot + _bias + _gamma * _impulse);
_impulse += impulse;
Vector2 P = impulse * _u;
b1._linearVelocity -= b1._invMass * P;
b1._angularVelocity -= b1._invI * MathUtils.Cross(r1, P);
b2._linearVelocity += b2._invMass * P;
b2._angularVelocity += b2._invI * MathUtils.Cross(r2, P);
}
internal override void SolveVelocityConstraints(ref TimeStep step)
{
Body b = _bodyB;
XForm xf1;
b.GetXForm(out xf1);
Vector2 r = MathUtils.Multiply(ref xf1.R, _localAnchor - b.GetLocalCenter());
// Cdot = v + cross(w, r)
Vector2 Cdot = b._linearVelocity + MathUtils.Cross(b._angularVelocity, r);
Vector2 impulse = MathUtils.Multiply(ref _mass, -(Cdot + _beta * _C + _gamma * _impulse));
Vector2 oldImpulse = _impulse;
_impulse += impulse;
float maxImpulse = step.dt * _maxForce;
if (_impulse.LengthSquared() > maxImpulse * maxImpulse)
{
_impulse *= maxImpulse / _impulse.Length();
}
impulse = _impulse - oldImpulse;
b._linearVelocity += b._invMass * impulse;
b._angularVelocity += b._invI * MathUtils.Cross(r, impulse);
}
internal override void InitVelocityConstraints(ref TimeStep step)
{
Body b = _bodyB;
float mass = b.GetMass();
// Frequency
float omega = 2.0f * Settings.b2_pi * _frequencyHz;
// Damping coefficient
float d = 2.0f * mass * _dampingRatio * omega;
// Spring stiffness
float k = mass * (omega * omega);
// magic formulas
// gamma has units of inverse mass.
// beta has units of inverse time.
Debug.Assert(d + step.dt * k > Settings.b2_FLT_EPSILON);
_gamma = 1.0f / (step.dt * (d + step.dt * k));
_beta = step.dt * k * _gamma;
// Compute the effective mass matrix.
XForm xf1;
b.GetXForm(out xf1);
Vector2 r = MathUtils.Multiply(ref xf1.R, _localAnchor - b.GetLocalCenter());
// 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]
float invMass = b._invMass;
float invI = b._invI;
Mat22 K1 = new Mat22(new Vector2(invMass, 0.0f), new Vector2(0.0f, invMass));
Mat22 K2 = new Mat22(new Vector2(invI * r.Y * r.Y, -invI * r.X * r.Y), new Vector2(-invI * r.X * r.Y, invI * r.X * r.X));
Mat22 K;
Mat22.Add(ref K1, ref K2, out K);
K.col1.X += _gamma;
K.col2.Y += _gamma;
_mass = K.GetInverse();
_C = b._sweep.c + r - _target;
// Cheat with some damping
b._angularVelocity *= 0.98f;
// Warm starting.
_impulse *= step.dtRatio;
b._linearVelocity += invMass * _impulse;
b._angularVelocity += invI * MathUtils.Cross(r, _impulse);
}
internal override void Evaluate()
{
Body bodyA = _fixtureA.GetBody();
Body bodyB = _fixtureB.GetBody();
XForm xfA, xfB;
bodyA.GetXForm(out xfA);
bodyB.GetXForm(out xfB);
Collision.CollideCircles(ref _manifold,
(CircleShape)_fixtureA.GetShape(), ref xfA,
(CircleShape)_fixtureB.GetShape(), ref xfB);
}
internal override void Evaluate()
{
Body b1 = _fixtureA.GetBody();
Body b2 = _fixtureB.GetBody();
XForm xf1, xf2;
b1.GetXForm(out xf1);
b2.GetXForm(out xf2);
Collision.CollidePolygonAndCircle(ref _manifold,
(PolygonShape)_fixtureA.GetShape(), ref xf1,
(CircleShape)_fixtureB.GetShape(), ref xf2);
}
void DrawJoint(Joint joint)
{
Body b1 = joint.GetBody1();
Body b2 = joint.GetBody2();
XForm xf1, xf2;
b1.GetXForm(out xf1);
b2.GetXForm(out xf2);
Vector2 x1 = xf1.Position;
Vector2 x2 = xf2.Position;
Vector2 p1 = joint.GetAnchor1();
Vector2 p2 = joint.GetAnchor2();
Color color = ColorEx.FromScRgb(0.5f, 0.8f, 0.8f);
switch (joint.JointType)
{
case JointType.Distance:
DebugDraw.DrawSegment(p1, p2, color);
break;
case JointType.Pulley:
{
PulleyJoint pulley = (PulleyJoint)joint;
Vector2 s1 = pulley.GetGroundAnchor1();
Vector2 s2 = pulley.GetGroundAnchor2();
DebugDraw.DrawSegment(s1, p1, color);
DebugDraw.DrawSegment(s2, p2, color);
DebugDraw.DrawSegment(s1, s2, color);
}
break;
case JointType.Mouse:
// don't draw this
break;
default:
DebugDraw.DrawSegment(x1, p1, color);
DebugDraw.DrawSegment(p1, p2, color);
DebugDraw.DrawSegment(x2, p2, color);
break;
}
}
internal override bool SolvePositionConstraints(float baumgarte)
{
if (_frequencyHz > 0.0f)
{
// There is no position correction for soft distance raints.
return(true);
}
Body b1 = _bodyA;
Body b2 = _bodyB;
XForm xf1, xf2;
b1.GetXForm(out xf1);
b2.GetXForm(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.Length();
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 void InitVelocityConstraints(ref TimeStep step)
{
Body b1 = _bodyA;
Body b2 = _bodyB;
if (_enableMotor || _enableLimit)
{
// You cannot create a rotation limit between bodies that
// both have fixed rotation.
Debug.Assert(b1._invI > 0.0f || b2._invI > 0.0f);
}
// Compute the effective mass matrix.
XForm xf1, xf2;
b1.GetXForm(out xf1);
b2.GetXForm(out xf2);
Vector2 r1 = MathUtils.Multiply(ref xf1.R, _localAnchor1 - b1.GetLocalCenter());
Vector2 r2 = MathUtils.Multiply(ref xf2.R, _localAnchor2 - b2.GetLocalCenter());
// J = [-I -r1_skew I r2_skew]
// [ 0 -1 0 1]
// r_skew = [-ry; rx]
// Matlab
// K = [ m1+r1y^2*i1+m2+r2y^2*i2, -r1y*i1*r1x-r2y*i2*r2x, -r1y*i1-r2y*i2]
// [ -r1y*i1*r1x-r2y*i2*r2x, m1+r1x^2*i1+m2+r2x^2*i2, r1x*i1+r2x*i2]
// [ -r1y*i1-r2y*i2, r1x*i1+r2x*i2, i1+i2]
float m1 = b1._invMass, m2 = b2._invMass;
float i1 = b1._invI, i2 = b2._invI;
_mass.col1.X = m1 + m2 + r1.Y * r1.Y * i1 + r2.Y * r2.Y * i2;
_mass.col2.X = -r1.Y * r1.X * i1 - r2.Y * r2.X * i2;
_mass.col3.X = -r1.Y * i1 - r2.Y * i2;
_mass.col1.Y = _mass.col2.X;
_mass.col2.Y = m1 + m2 + r1.X * r1.X * i1 + r2.X * r2.X * i2;
_mass.col3.Y = r1.X * i1 + r2.X * i2;
_mass.col1.Z = _mass.col3.X;
_mass.col2.Z = _mass.col3.Y;
_mass.col3.Z = i1 + i2;
_motorMass = 1.0f / (i1 + i2);
if (_enableMotor == false)
{
_motorImpulse = 0.0f;
}
if (_enableLimit)
{
float jointAngle = b2._sweep.a - b1._sweep.a - _referenceAngle;
if (Math.Abs(_upperAngle - _lowerAngle) < 2.0f * Settings.b2_angularSlop)
{
_limitState = LimitState.Equal;
}
else if (jointAngle <= _lowerAngle)
{
if (_limitState != LimitState.AtLower)
{
_impulse.Z = 0.0f;
}
_limitState = LimitState.AtLower;
}
else if (jointAngle >= _upperAngle)
{
if (_limitState != LimitState.AtUpper)
{
_impulse.Z = 0.0f;
}
_limitState = LimitState.AtUpper;
}
else
{
_limitState = LimitState.Inactive;
_impulse.Z = 0.0f;
}
}
else
{
_limitState = LimitState.Inactive;
}
if (step.warmStarting)
{
// Scale impulses to support a variable time step.
_impulse *= step.dtRatio;
_motorImpulse *= step.dtRatio;
Vector2 P = new Vector2(_impulse.X, _impulse.Y);
b1._linearVelocity -= m1 * P;
b1._angularVelocity -= i1 * (MathUtils.Cross(r1, P) + _motorImpulse + _impulse.Z);
b2._linearVelocity += m2 * P;
b2._angularVelocity += i2 * (MathUtils.Cross(r2, P) + _motorImpulse + _impulse.Z);
}
else
{
_impulse = Vector3.Zero;
_motorImpulse = 0.0f;
}
}
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 raint.
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 raint.
{
XForm xf1, xf2;
b1.GetXForm(out xf1);
b2.GetXForm(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.Length();
float invMass1 = b1._invMass, invMass2 = b2._invMass;
float invI1 = b1._invI, invI2 = b2._invI;
// Handle large detachment.
float k_allowedStretch = 10.0f * Settings.b2_linearSlop;
if (C.LengthSquared() > k_allowedStretch * k_allowedStretch)
{
// Use a particle solution (no rotation).
Vector2 u = C; u.Normalize();
float k = invMass1 + invMass2;
Debug.Assert(k > Settings.b2_FLT_EPSILON);
float m = 1.0f / k;
Vector2 impulse2 = m * (-C);
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 void InitVelocityConstraints(ref TimeStep step)
{
Body b1 = _bodyA;
Body b2 = _bodyB;
XForm xf1, xf2;
b1.GetXForm(out xf1);
b2.GetXForm(out xf2);
// Compute the effective mass matrix.
Vector2 r1 = MathUtils.Multiply(ref xf1.R, _localAnchor1 - b1.GetLocalCenter());
Vector2 r2 = MathUtils.Multiply(ref xf2.R, _localAnchor2 - b2.GetLocalCenter());
_u = b2._sweep.c + r2 - b1._sweep.c - r1;
// Handle singularity.
float length = _u.Length();
if (length > Settings.b2_linearSlop)
{
_u *= 1.0f / length;
}
else
{
_u = new Vector2(0.0f, 0.0f);
}
float cr1u = MathUtils.Cross(r1, _u);
float cr2u = MathUtils.Cross(r2, _u);
float invMass = b1._invMass + b1._invI * cr1u * cr1u + b2._invMass + b2._invI * cr2u * cr2u;
Debug.Assert(invMass > Settings.b2_FLT_EPSILON);
_mass = 1.0f / invMass;
if (_frequencyHz > 0.0f)
{
float C = length - _length;
// Frequency
float omega = 2.0f * Settings.b2_pi * _frequencyHz;
// Damping coefficient
float d = 2.0f * _mass * _dampingRatio * omega;
// Spring stiffness
float k = _mass * omega * omega;
// magic formulas
_gamma = 1.0f / (step.dt * (d + step.dt * k));
_bias = C * step.dt * k * _gamma;
_mass = 1.0f / (invMass + _gamma);
}
if (step.warmStarting)
{
// Scale the impulse to support a variable time step.
_impulse *= step.dtRatio;
Vector2 P = _impulse * _u;
b1._linearVelocity -= b1._invMass * P;
b1._angularVelocity -= b1._invI * MathUtils.Cross(r1, P);
b2._linearVelocity += b2._invMass * P;
b2._angularVelocity += b2._invI * MathUtils.Cross(r2, P);
}
else
{
_impulse = 0.0f;
}
}
internal override void InitVelocityConstraints(ref TimeStep step)
{
Body b1 = _bodyA;
Body b2 = _bodyB;
// You cannot create a prismatic joint between bodies that
// both have fixed rotation.
Debug.Assert(b1._invI > 0.0f || b2._invI > 0.0f);
_localCenter1 = b1.GetLocalCenter();
_localCenter2 = b2.GetLocalCenter();
XForm xf1, xf2;
b1.GetXForm(out xf1);
b2.GetXForm(out xf2);
// Compute the effective masses.
Vector2 r1 = MathUtils.Multiply(ref xf1.R, _localAnchor1 - _localCenter1);
Vector2 r2 = MathUtils.Multiply(ref xf2.R, _localAnchor2 - _localCenter2);
Vector2 d = b2._sweep.c + r2 - b1._sweep.c - r1;
_invMass1 = b1._invMass;
_invI1 = b1._invI;
_invMass2 = b2._invMass;
_invI2 = b2._invI;
// Compute motor Jacobian and effective mass.
{
_axis = MathUtils.Multiply(ref xf1.R, _localXAxis1);
_a1 = MathUtils.Cross(d + r1, _axis);
_a2 = MathUtils.Cross(r2, _axis);
_motorMass = _invMass1 + _invMass2 + _invI1 * _a1 * _a1 + _invI2 * _a2 * _a2;
Debug.Assert(_motorMass > Settings.b2_FLT_EPSILON);
_motorMass = 1.0f / _motorMass;
}
// Prismatic raint.
{
_perp = MathUtils.Multiply(ref xf1.R, _localYAxis1);
_s1 = MathUtils.Cross(d + r1, _perp);
_s2 = MathUtils.Cross(r2, _perp);
float m1 = _invMass1, m2 = _invMass2;
float i1 = _invI1, i2 = _invI2;
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);
}
// Compute motor and limit terms.
if (_enableLimit)
{
float jointTranslation = Vector2.Dot(_axis, d);
if (Math.Abs(_upperTranslation - _lowerTranslation) < 2.0f * Settings.b2_linearSlop)
{
_limitState = LimitState.Equal;
}
else if (jointTranslation <= _lowerTranslation)
{
if (_limitState != LimitState.AtLower)
{
_limitState = LimitState.AtLower;
_impulse.Z = 0.0f;
}
}
else if (jointTranslation >= _upperTranslation)
{
if (_limitState != LimitState.AtUpper)
{
_limitState = LimitState.AtUpper;
_impulse.Z = 0.0f;
}
}
else
{
_limitState = LimitState.Inactive;
_impulse.Z = 0.0f;
}
}
else
{
_limitState = LimitState.Inactive;
}
if (_enableMotor == false)
{
_motorImpulse = 0.0f;
}
if (step.warmStarting)
{
// Account for variable time step.
_impulse *= step.dtRatio;
_motorImpulse *= step.dtRatio;
Vector2 P = _impulse.X * _perp + (_motorImpulse + _impulse.Z) * _axis;
float L1 = _impulse.X * _s1 + _impulse.Y + (_motorImpulse + _impulse.Z) * _a1;
float L2 = _impulse.X * _s2 + _impulse.Y + (_motorImpulse + _impulse.Z) * _a2;
b1._linearVelocity -= _invMass1 * P;
b1._angularVelocity -= _invI1 * L1;
b2._linearVelocity += _invMass2 * P;
b2._angularVelocity += _invI2 * L2;
}
else
{
_impulse = Vector3.Zero;
_motorImpulse = 0.0f;
}
}
internal override void InitVelocityConstraints(ref TimeStep step)
{
Body g1 = _ground1;
Body g2 = _ground2;
Body b1 = _bodyA;
Body b2 = _bodyB;
float K = 0.0f;
_J.SetZero();
if (_revolute1 != null)
{
_J.angular1 = -1.0f;
K += b1._invI;
}
else
{
XForm xf1, xfg1;
b1.GetXForm(out xf1);
g1.GetXForm(out xfg1);
Vector2 ug = MathUtils.Multiply(ref xfg1.R, _prismatic1._localXAxis1);
Vector2 r = MathUtils.Multiply(ref xf1.R, _localAnchor1 - b1.GetLocalCenter());
float crug = MathUtils.Cross(r, ug);
_J.linear1 = -ug;
_J.angular1 = -crug;
K += b1._invMass + b1._invI * crug * crug;
}
if (_revolute2 != null)
{
_J.angular2 = -_ratio;
K += _ratio * _ratio * b2._invI;
}
else
{
XForm xfg1, xf2;
g1.GetXForm(out xfg1);
b2.GetXForm(out xf2);
Vector2 ug = MathUtils.Multiply(ref xfg1.R, _prismatic2._localXAxis1);
Vector2 r = MathUtils.Multiply(ref xf2.R, _localAnchor2 - b2.GetLocalCenter());
float crug = MathUtils.Cross(r, ug);
_J.linear2 = -_ratio * ug;
_J.angular2 = -_ratio * crug;
K += _ratio * _ratio * (b2._invMass + b2._invI * crug * crug);
}
// Compute effective mass.
Debug.Assert(K > 0.0f);
_mass = 1.0f / K;
if (step.warmStarting)
{
// Warm starting.
b1._linearVelocity += b1._invMass * _impulse * _J.linear1;
b1._angularVelocity += b1._invI * _impulse * _J.angular1;
b2._linearVelocity += b2._invMass * _impulse * _J.linear2;
b2._angularVelocity += b2._invI * _impulse * _J.angular2;
}
else
{
_impulse = 0.0f;
}
}
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)
{
XForm xf1, xf2;
b1.GetXForm(out xf1);
b2.GetXForm(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.Length();
float length2 = _u2.Length();
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)
{
XForm xf1;
b1.GetXForm(out xf1);
Vector2 r1 = MathUtils.Multiply(ref xf1.R, _localAnchor1 - b1.GetLocalCenter());
Vector2 p1 = b1._sweep.c + r1;
_u1 = p1 - s1;
float length1 = _u1.Length();
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)
{
XForm xf2;
b2.GetXForm(out xf2);
Vector2 r2 = MathUtils.Multiply(ref xf2.R, _localAnchor2 - b2.GetLocalCenter());
Vector2 p2 = b2._sweep.c + r2;
_u2 = p2 - s2;
float length2 = _u2.Length();
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);
}
internal override void SolveVelocityConstraints(ref TimeStep step)
{
Body b1 = _bodyA;
Body b2 = _bodyB;
XForm xf1, xf2;
b1.GetXForm(out xf1);
b2.GetXForm(out xf2);
Vector2 r1 = MathUtils.Multiply(ref xf1.R, _localAnchor1 - b1.GetLocalCenter());
Vector2 r2 = MathUtils.Multiply(ref xf2.R, _localAnchor2 - b2.GetLocalCenter());
if (_state == LimitState.AtUpper)
{
Vector2 v1 = b1._linearVelocity + MathUtils.Cross(b1._angularVelocity, r1);
Vector2 v2 = b2._linearVelocity + MathUtils.Cross(b2._angularVelocity, r2);
float Cdot = -Vector2.Dot(_u1, v1) - _ratio * Vector2.Dot(_u2, v2);
float impulse = _pulleyMass * (-Cdot);
float oldImpulse = _impulse;
_impulse = Math.Max(0.0f, _impulse + impulse);
impulse = _impulse - oldImpulse;
Vector2 P1 = -impulse * _u1;
Vector2 P2 = -_ratio * impulse * _u2;
b1._linearVelocity += b1._invMass * P1;
b1._angularVelocity += b1._invI * MathUtils.Cross(r1, P1);
b2._linearVelocity += b2._invMass * P2;
b2._angularVelocity += b2._invI * MathUtils.Cross(r2, P2);
}
if (_limitState1 == LimitState.AtUpper)
{
Vector2 v1 = b1._linearVelocity + MathUtils.Cross(b1._angularVelocity, r1);
float Cdot = -Vector2.Dot(_u1, v1);
float impulse = -_limitMass1 * Cdot;
float oldImpulse = _limitImpulse1;
_limitImpulse1 = Math.Max(0.0f, _limitImpulse1 + impulse);
impulse = _limitImpulse1 - oldImpulse;
Vector2 P1 = -impulse * _u1;
b1._linearVelocity += b1._invMass * P1;
b1._angularVelocity += b1._invI * MathUtils.Cross(r1, P1);
}
if (_limitState2 == LimitState.AtUpper)
{
Vector2 v2 = b2._linearVelocity + MathUtils.Cross(b2._angularVelocity, r2);
float Cdot = -Vector2.Dot(_u2, v2);
float impulse = -_limitMass2 * Cdot;
float oldImpulse = _limitImpulse2;
_limitImpulse2 = Math.Max(0.0f, _limitImpulse2 + impulse);
impulse = _limitImpulse2 - oldImpulse;
Vector2 P2 = -impulse * _u2;
b2._linearVelocity += b2._invMass * P2;
b2._angularVelocity += b2._invI * MathUtils.Cross(r2, P2);
}
}
internal override void InitVelocityConstraints(ref TimeStep step)
{
Body b1 = _bodyA;
Body b2 = _bodyB;
XForm xf1, xf2;
b1.GetXForm(out xf1);
b2.GetXForm(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;
Vector2 s1 = _groundAnchor1;
Vector2 s2 = _groundAnchor2;
// Get the pulley axes.
_u1 = p1 - s1;
_u2 = p2 - s2;
float length1 = _u1.Length();
float length2 = _u2.Length();
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;
if (C > 0.0f)
{
_state = LimitState.Inactive;
_impulse = 0.0f;
}
else
{
_state = LimitState.AtUpper;
}
if (length1 < _maxLength1)
{
_limitState1 = LimitState.Inactive;
_limitImpulse1 = 0.0f;
}
else
{
_limitState1 = LimitState.AtUpper;
}
if (length2 < _maxLength2)
{
_limitState2 = LimitState.Inactive;
_limitImpulse2 = 0.0f;
}
else
{
_limitState2 = LimitState.AtUpper;
}
// Compute effective mass.
float cr1u1 = MathUtils.Cross(r1, _u1);
float cr2u2 = MathUtils.Cross(r2, _u2);
_limitMass1 = b1._invMass + b1._invI * cr1u1 * cr1u1;
_limitMass2 = b2._invMass + b2._invI * cr2u2 * cr2u2;
_pulleyMass = _limitMass1 + _ratio * _ratio * _limitMass2;
Debug.Assert(_limitMass1 > Settings.b2_FLT_EPSILON);
Debug.Assert(_limitMass2 > Settings.b2_FLT_EPSILON);
Debug.Assert(_pulleyMass > Settings.b2_FLT_EPSILON);
_limitMass1 = 1.0f / _limitMass1;
_limitMass2 = 1.0f / _limitMass2;
_pulleyMass = 1.0f / _pulleyMass;
if (step.warmStarting)
{
// Scale impulses to support variable time steps.
_impulse *= step.dtRatio;
_limitImpulse1 *= step.dtRatio;
_limitImpulse2 *= step.dtRatio;
// Warm starting.
Vector2 P1 = -(_impulse + _limitImpulse1) * _u1;
Vector2 P2 = (-_ratio * _impulse - _limitImpulse2) * _u2;
b1._linearVelocity += b1._invMass * P1;
b1._angularVelocity += b1._invI * MathUtils.Cross(r1, P1);
b2._linearVelocity += b2._invMass * P2;
b2._angularVelocity += b2._invI * MathUtils.Cross(r2, P2);
}
else
{
_impulse = 0.0f;
_limitImpulse1 = 0.0f;
_limitImpulse2 = 0.0f;
}
}
internal override void SolveVelocityConstraints(ref TimeStep step)
{
Body b1 = _bodyA;
Body b2 = _bodyB;
Vector2 v1 = b1._linearVelocity;
float w1 = b1._angularVelocity;
Vector2 v2 = b2._linearVelocity;
float w2 = b2._angularVelocity;
float m1 = b1._invMass, m2 = b2._invMass;
float i1 = b1._invI, i2 = b2._invI;
// Solve motor raint.
if (_enableMotor && _limitState != LimitState.Equal)
{
float Cdot = w2 - w1 - _motorSpeed;
float impulse = _motorMass * (-Cdot);
float oldImpulse = _motorImpulse;
float maxImpulse = step.dt * _maxMotorTorque;
_motorImpulse = MathUtils.Clamp(_motorImpulse + impulse, -maxImpulse, maxImpulse);
impulse = _motorImpulse - oldImpulse;
w1 -= i1 * impulse;
w2 += i2 * impulse;
}
// Solve limit raint.
if (_enableLimit && _limitState != LimitState.Inactive)
{
XForm xf1, xf2;
b1.GetXForm(out xf1);
b2.GetXForm(out xf2);
Vector2 r1 = MathUtils.Multiply(ref xf1.R, _localAnchor1 - b1.GetLocalCenter());
Vector2 r2 = MathUtils.Multiply(ref xf2.R, _localAnchor2 - b2.GetLocalCenter());
// Solve point-to-point raint
Vector2 Cdot1 = v2 + MathUtils.Cross(w2, r2) - v1 - MathUtils.Cross(w1, r1);
float Cdot2 = w2 - w1;
Vector3 Cdot = new Vector3(Cdot1.X, Cdot1.Y, Cdot2);
Vector3 impulse = _mass.Solve33(-Cdot);
if (_limitState == LimitState.Equal)
{
_impulse += impulse;
}
else if (_limitState == LimitState.AtLower)
{
float newImpulse = _impulse.Z + impulse.Z;
if (newImpulse < 0.0f)
{
Vector2 reduced = _mass.Solve22(-Cdot1);
impulse.X = reduced.X;
impulse.Y = reduced.Y;
impulse.Z = -_impulse.Z;
_impulse.X += reduced.X;
_impulse.Y += reduced.Y;
_impulse.Z = 0.0f;
}
}
else if (_limitState == LimitState.AtUpper)
{
float newImpulse = _impulse.Z + impulse.Z;
if (newImpulse > 0.0f)
{
Vector2 reduced = _mass.Solve22(-Cdot1);
impulse.X = reduced.X;
impulse.Y = reduced.Y;
impulse.Z = -_impulse.Z;
_impulse.X += reduced.X;
_impulse.Y += reduced.Y;
_impulse.Z = 0.0f;
}
}
Vector2 P = new Vector2(impulse.X, impulse.Y);
v1 -= m1 * P;
w1 -= i1 * (MathUtils.Cross(r1, P) + impulse.Z);
v2 += m2 * P;
w2 += i2 * (MathUtils.Cross(r2, P) + impulse.Z);
}
else
{
XForm xf1, xf2;
b1.GetXForm(out xf1);
b2.GetXForm(out xf2);
Vector2 r1 = MathUtils.Multiply(ref xf1.R, _localAnchor1 - b1.GetLocalCenter());
Vector2 r2 = MathUtils.Multiply(ref xf2.R, _localAnchor2 - b2.GetLocalCenter());
// Solve point-to-point raint
Vector2 Cdot = v2 + MathUtils.Cross(w2, r2) - v1 - MathUtils.Cross(w1, r1);
Vector2 impulse = _mass.Solve22(-Cdot);
_impulse.X += impulse.X;
_impulse.Y += impulse.Y;
v1 -= m1 * impulse;
w1 -= i1 * MathUtils.Cross(r1, impulse);
v2 += m2 * impulse;
w2 += i2 * MathUtils.Cross(r2, impulse);
}
b1._linearVelocity = v1;
b1._angularVelocity = w1;
b2._linearVelocity = v2;
b2._angularVelocity = w2;
}
/// Call this to draw shapes and other debug draw data.
public void DrawDebugData()
{
if (DebugDraw == null)
{
return;
}
DebugDrawFlags flags = DebugDraw.Flags;
if ((flags & DebugDrawFlags.Shape) == DebugDrawFlags.Shape)
{
for (Body b = _bodyList; b != null; b = b.GetNext())
{
XForm xf;
b.GetXForm(out xf);
for (Fixture f = b.GetFixtureList(); f != null; f = f.GetNext())
{
if (b.IsStatic)
{
DrawShape(f, xf, ColorEx.FromScRgb(0.5f, 0.9f, 0.5f));
}
else if (b.IsSleeping)
{
DrawShape(f, xf, ColorEx.FromScRgb(0.5f, 0.5f, 0.9f));
}
else
{
DrawShape(f, xf, ColorEx.FromScRgb(0.9f, 0.9f, 0.9f));
}
}
}
}
if ((flags & DebugDrawFlags.Joint) == DebugDrawFlags.Joint)
{
for (Joint j = _jointList; j != null; j = j.GetNext())
{
if (j.JointType != JointType.Mouse)
{
DrawJoint(j);
}
}
}
if ((flags & DebugDrawFlags.Pair) == DebugDrawFlags.Pair)
{
// TODO
}
if ((flags & DebugDrawFlags.AABB) == DebugDrawFlags.AABB)
{
Color color = ColorEx.FromScRgb(0.9f, 0.3f, 0.9f);
BroadPhase bp = _contactManager._broadPhase;
for (Body b = _bodyList; b != null; b = b.GetNext())
{
for (Fixture f = b.GetFixtureList(); f != null; f = f.GetNext())
{
AABB aabb;
bp.GetAABB(f._proxyId, out aabb);
FixedArray8 <Vector2> vs = new FixedArray8 <Vector2>();
vs[0] = new Vector2(aabb.lowerBound.X, aabb.lowerBound.Y);
vs[1] = new Vector2(aabb.upperBound.X, aabb.lowerBound.Y);
vs[2] = new Vector2(aabb.upperBound.X, aabb.upperBound.Y);
vs[3] = new Vector2(aabb.lowerBound.X, aabb.upperBound.Y);
DebugDraw.DrawPolygon(ref vs, 4, color);
}
}
}
if ((flags & DebugDrawFlags.CenterOfMass) == DebugDrawFlags.CenterOfMass)
{
for (Body b = _bodyList; b != null; b = b.GetNext())
{
XForm xf;
b.GetXForm(out xf);
xf.Position = b.GetWorldCenter();
DebugDraw.DrawXForm(ref xf);
}
}
}
