private void SetJointTorque(RevoluteJoint joint, float torque)
{
float atorque; // abs(torque)
float storque; // sign(torque)
if (torque > 0f)
{
atorque = torque;
storque = 1f;
}
else if (torque < 0f)
{
atorque = -torque;
storque = -1f;
}
else
{
atorque = 0f;
storque = 0f;
}
//#
//# We have to enumerate various cases because we are emulating friction
//# with active torque and we have to take care not to add energy to
//# the system when a reversal happens inside the timestep.
//#
//# Also, the underlying sim does not let us apply torque directly, but
//# rather we have to factor it into maxMotorTorque and motorSpeed, the
//# latter of which we set to an extreme we don't normally expect to reach.
//#
float speed = joint.JointSpeed;
float fric = __jointFriction;
if (speed * storque >= 0f) //# Pushing in same direction as current motion (and against friction)
{
if (atorque > fric) //# With enough force to overcome friction:
{
joint.SetMaxMotorTorque(atorque - fric); //# Remaining torque (after friction)...
joint.MotorSpeed = storque * 100f; //# serves to accelerate current motion
}
else //# Without enough force to overcome friction:
{
joint.SetMaxMotorTorque(fric - atorque); //# Remaining friction...
joint.MotorSpeed = 0f; //# ...serves to stop the motion (but no more)
}
}
else //# Pushing against current motion (and with friction)
{
joint.SetMaxMotorTorque(fric + atorque); //# Forces sum...
joint.MotorSpeed = storque * 100f; //# ...in direction of torque
//# BUG: This case unfortunately adds energy during reversals because friction
//# continues to contribute energy in the same direction after the reversal.
//# Is there a fix for this?
}
}
public override void Keyboard(System.Windows.Forms.Keys key)
{
switch (key)
{
case System.Windows.Forms.Keys.A:
_leftJoint.SetMaxMotorTorque(800.0f);
_leftJoint.MotorSpeed = 12.0f;
break;
case System.Windows.Forms.Keys.S:
_leftJoint.SetMaxMotorTorque(100.0f);
_leftJoint.MotorSpeed = 0.0f;
break;
case System.Windows.Forms.Keys.D:
_leftJoint.SetMaxMotorTorque(1200.0f);
_leftJoint.MotorSpeed = -36.0f;
break;
}
}
public override void Load()
{
// Ground body
Body ground;
{
ground = Physics.NewBody(m_world);
// outline
Physics.NewFixture(ground,
Physics.NewChainShape(true, new Vector2[]
{
new Vector2(0.0f, -2.0f),
new Vector2(8.0f, 6.0f),
new Vector2(8.0f, 20.0f),
new Vector2(-8.0f, 20.0f),
new Vector2(-8.0f, 6.0f),
}), 0);
}
// Flippers
{
var p1 = new Vector2(-2.0f, 0.0f);
var p2 = new Vector2(2.0f, 0.0f);
Body leftFlipper = Physics.NewBody(m_world, p1.X, p1.Y, BodyType.Dynamic);
Body rightFlipper = Physics.NewBody(m_world, p2.X, p2.Y, BodyType.Dynamic);
var box = Physics.NewRectangleShape(1.75f * 2, 0.1f * 2);
Physics.NewFixture(leftFlipper, box, 1.0f);
Physics.NewFixture(rightFlipper, box, 1.0f);
lrj = Physics.NewRevoluteJoint(ground, leftFlipper, p1);
lrj.SetMotorSpeed(0);
lrj.SetMotorEnabled(true);
lrj.SetLimitsEnabled(true);
lrj.SetMaxMotorTorque(1000.0f);
lrj.SetLimits(-30.0f * Mathf.PI / 180.0f, 5.0f * Mathf.PI / 180.0f);
rrj = Physics.NewRevoluteJoint(ground, rightFlipper, p2);
rrj.SetMotorSpeed(0);
rrj.SetMotorEnabled(true);
rrj.SetLimitsEnabled(true);
rrj.SetMaxMotorTorque(1000.0f);
rrj.SetLimits(-5.0f * Mathf.PI / 180.0f, 30.0f * Mathf.PI / 180.0f);
}
// Circle character
{
var body = Physics.NewBody(m_world, 1.0f, 15.0f, BodyType.Dynamic);
body.SetBullet(true);
Physics.NewFixture(body, Physics.NewCircleShape(0.2f), 1.0f);
}
}
public override void Load()
{
genDT = 0;
Body ground = Physics.NewBody(m_world);
{
Body body = Physics.NewBody(m_world, 0.0f * scale, 10.0f * scale, BodyType.Dynamic);
body.SetSleepingAllowed(false);
Physics.NewFixture(body,
NewRectShape(body, 10.0f * scale, 0.0f * scale, 0.5f * 2 * scale, 10.0f * 2 * scale),
5.0f * scale);
Physics.NewFixture(body,
NewRectShape(body, -10.0f * scale, 0.0f * scale, 0.5f * 2 * scale, 10.0f * 2 * scale),
5.0f * scale);
Physics.NewFixture(body,
NewRectShape(body, 0.0f * scale, 10.0f * scale, 10.0f * 2 * scale, 0.5f * 2 * scale),
5.0f * scale);
Physics.NewFixture(body,
NewRectShape(body, 0.0f * scale, -10.0f * scale, 10.0f * 2 * scale, 0.5f * 2 * scale),
5.0f * scale);
//RevoluteJoint jd = Physics.NewRevoluteJoint(ground, body,
// new Vector2(0.0f, 10.0f) * scale,
// new Vector2(0.0f, 0.0f) * scale
// );
RevoluteJoint jd = Physics.NewRevoluteJoint(ground, body,
new Vector2(0.0f, 10.0f) * scale,
new Vector2(0.0f, 10.0f) * scale
);
jd.SetMotorSpeed(-0.05f * Mathf.PI);
jd.SetMaxMotorTorque(1e8f * scale);
jd.SetMotorEnabled(true);
}
m_count = 0;
}