internal override void SolveVelocityConstraints(ref TimeStep step)
{
Body b2 = BodyB;
Vector2 v1 = Vector2.Zero;
float w1 = 0.0f;
Vector2 v2 = b2.LinearVelocityInternal;
float w2 = b2.AngularVelocityInternal;
// Solve linear motor constraint.
if (_enableMotor && _limitState != LimitState.Equal)
{
float Cdot = Vector2.Dot(_axis, v2 - v1) + _a2 * w2 - _a1 * w1;
float impulse = _motorMass * (_motorSpeed - Cdot);
float oldImpulse = _motorImpulse;
float maxImpulse = step.dt * _maxMotorForce;
_motorImpulse = MathUtils.Clamp(_motorImpulse + impulse, -maxImpulse, maxImpulse);
impulse = _motorImpulse - oldImpulse;
Vector2 P = impulse * _axis;
float L1 = impulse * _a1;
float L2 = impulse * _a2;
v1 -= InvMassA * P;
w1 -= InvIA * L1;
v2 += InvMassB * P;
w2 += InvIB * L2;
}
Vector2 Cdot1 = new Vector2(Vector2.Dot(_perp, v2 - v1) + _s2 * w2 - _s1 * w1, w2 - w1);
if (_enableLimit && _limitState != LimitState.Inactive)
{
// Solve prismatic and limit constraint in block form.
float Cdot2 = Vector2.Dot(_axis, v2 - v1) + _a2 * w2 - _a1 * w1;
Vector3 Cdot = new Vector3(Cdot1.X, Cdot1.Y, Cdot2);
Vector3 f1 = _impulse;
Vector3 df = _K.Solve33(-Cdot);
_impulse += df;
if (_limitState == LimitState.AtLower)
{
_impulse.Z = Math.Max(_impulse.Z, 0.0f);
}
else if (_limitState == LimitState.AtUpper)
{
_impulse.Z = Math.Min(_impulse.Z, 0.0f);
}
// f2(1:2) = invK(1:2,1:2) * (-Cdot(1:2) - K(1:2,3) * (f2(3) - f1(3))) + f1(1:2)
Vector2 b = -Cdot1 - (_impulse.Z - f1.Z) * new Vector2(_K.col3.X, _K.col3.Y);
Vector2 f2r = _K.Solve22(b) + new Vector2(f1.X, f1.Y);
_impulse.X = f2r.X;
_impulse.Y = f2r.Y;
df = _impulse - f1;
Vector2 P = df.X * _perp + df.Z * _axis;
float L2 = df.X * _s2 + df.Y + df.Z * _a2;
v2 += InvMassB * P;
w2 += InvIB * L2;
}
else
{
// Limit is inactive, just solve the prismatic constraint in block form.
Vector2 df = _K.Solve22(-Cdot1);
_impulse.X += df.X;
_impulse.Y += df.Y;
Vector2 P = df.X * _perp;
float L2 = df.X * _s2 + df.Y;
v2 += InvMassB * P;
w2 += InvIB * L2;
}
b2.LinearVelocityInternal = v2;
b2.AngularVelocityInternal = w2;
}
