public void Add(PhysicsJoint joint)
{
Debug.Assert(JointCount < _jointCapacity);
_joints[JointCount++] = joint;
}
/// <summary>
/// Requires two existing revolute or prismatic joints (any combination will work).
/// The provided joints must attach a dynamic body to a static body.
/// </summary>
/// <param name="jointA">The first joint.</param>
/// <param name="jointB">The second joint.</param>
/// <param name="ratio">The ratio.</param>
public GearJoint(PhysicsJoint jointA, PhysicsJoint jointB, float ratio)
: base(jointA.BodyA, jointA.BodyB)
{
JointType = JointType.Gear;
JointA = jointA;
JointB = jointB;
Ratio = ratio;
JointType type1 = jointA.JointType;
JointType type2 = jointB.JointType;
// Make sure its the right kind of joint
Debug.Assert(type1 == JointType.Revolute ||
type1 == JointType.Prismatic ||
type1 == JointType.FixedRevolute ||
type1 == JointType.FixedPrismatic);
Debug.Assert(type2 == JointType.Revolute ||
type2 == JointType.Prismatic ||
type2 == JointType.FixedRevolute ||
type2 == JointType.FixedPrismatic);
// In the case of a prismatic and revolute joint, the first body must be static.
if (type1 == JointType.Revolute || type1 == JointType.Prismatic)
Debug.Assert(jointA.BodyA.BodyType == BodyType.Static);
if (type2 == JointType.Revolute || type2 == JointType.Prismatic)
Debug.Assert(jointB.BodyA.BodyType == BodyType.Static);
float coordinate1 = 0.0f, coordinate2 = 0.0f;
switch (type1)
{
case JointType.Revolute:
BodyA = jointA.BodyB;
_revolute1 = (RevoluteJoint)jointA;
LocalAnchor1 = _revolute1.LocalAnchorB;
coordinate1 = _revolute1.JointAngle;
break;
case JointType.Prismatic:
BodyA = jointA.BodyB;
_prismatic1 = (PrismaticJoint)jointA;
LocalAnchor1 = _prismatic1.LocalAnchorB;
coordinate1 = _prismatic1.JointTranslation;
break;
case JointType.FixedRevolute:
BodyA = jointA.BodyA;
_fixedRevolute1 = (FixedRevoluteJoint)jointA;
LocalAnchor1 = _fixedRevolute1.LocalAnchorA;
coordinate1 = _fixedRevolute1.JointAngle;
break;
case JointType.FixedPrismatic:
BodyA = jointA.BodyA;
_fixedPrismatic1 = (FixedPrismaticJoint)jointA;
LocalAnchor1 = _fixedPrismatic1.LocalAnchorA;
coordinate1 = _fixedPrismatic1.JointTranslation;
break;
}
switch (type2)
{
case JointType.Revolute:
BodyB = jointB.BodyB;
_revolute2 = (RevoluteJoint)jointB;
LocalAnchor2 = _revolute2.LocalAnchorB;
coordinate2 = _revolute2.JointAngle;
break;
case JointType.Prismatic:
BodyB = jointB.BodyB;
_prismatic2 = (PrismaticJoint)jointB;
LocalAnchor2 = _prismatic2.LocalAnchorB;
coordinate2 = _prismatic2.JointTranslation;
break;
case JointType.FixedRevolute:
BodyB = jointB.BodyA;
_fixedRevolute2 = (FixedRevoluteJoint)jointB;
LocalAnchor2 = _fixedRevolute2.LocalAnchorA;
coordinate2 = _fixedRevolute2.JointAngle;
break;
case JointType.FixedPrismatic:
BodyB = jointB.BodyA;
_fixedPrismatic2 = (FixedPrismaticJoint)jointB;
LocalAnchor2 = _fixedPrismatic2.LocalAnchorA;
coordinate2 = _fixedPrismatic2.JointTranslation;
break;
}
_ant = coordinate1 + Ratio * coordinate2;
}
/// <summary>
/// Destroy a joint. This may cause the connected bodies to begin colliding.
/// </summary>
/// <param name="joint">The joint.</param>
public void RemoveJoint(PhysicsJoint joint)
{
RemoveJoint(joint, true);
}
/// <summary>
/// Create a joint to constrain bodies together. This may cause the connected bodies to cease colliding.
/// </summary>
/// <param name="joint">The joint.</param>
public void AddJoint(PhysicsJoint joint)
{
Debug.Assert(!_jointAddList.Contains(joint), "You are adding the same joint more than once.");
if (!_jointAddList.Contains(joint))
_jointAddList.Add(joint);
}
private void RemoveJoint(PhysicsJoint joint, bool doCheck)
{
if (doCheck)
{
Debug.Assert(!_jointRemoveList.Contains(joint),
"The joint is already marked for removal. You are removing the joint more than once.");
}
if (!_jointRemoveList.Contains(joint))
_jointRemoveList.Add(joint);
}
public static GearJoint CreateGearJoint(PhysicsWorld world, PhysicsJoint jointA, PhysicsJoint jointB, float ratio)
{
GearJoint gearJoint = new GearJoint(jointA, jointB, ratio);
world.AddJoint(gearJoint);
return gearJoint;
}
private void SerializeJoint(PhysicsJoint joint)
{
if (joint.IsFixedType())
return;
_writer.WriteStartElement("Joint");
_writer.WriteAttributeString("Type", joint.JointType.ToString());
WriteElement("BodyA", FindBodyIndex(joint.BodyA));
WriteElement("BodyB", FindBodyIndex(joint.BodyB));
WriteElement("CollideConnected", joint.CollideConnected);
WriteElement("Breakpoint", joint.Breakpoint);
if (joint.UserData != null)
{
_writer.WriteStartElement("UserData");
WriteDynamicType(joint.UserData.GetType(), joint.UserData);
_writer.WriteEndElement();
}
switch (joint.JointType)
{
case JointType.Distance:
{
DistanceJoint djd = (DistanceJoint)joint;
WriteElement("DampingRatio", djd.DampingRatio);
WriteElement("FrequencyHz", djd.Frequency);
WriteElement("Length", djd.Length);
WriteElement("LocalAnchorA", djd.LocalAnchorA);
WriteElement("LocalAnchorB", djd.LocalAnchorB);
}
break;
case JointType.Friction:
{
FrictionJoint fjd = (FrictionJoint)joint;
WriteElement("LocalAnchorA", fjd.LocalAnchorA);
WriteElement("LocalAnchorB", fjd.LocalAnchorB);
WriteElement("MaxForce", fjd.MaxForce);
WriteElement("MaxTorque", fjd.MaxTorque);
}
break;
case JointType.Gear:
throw new Exception("Gear joint not supported by serialization");
case JointType.Line:
{
LineJoint ljd = (LineJoint)joint;
WriteElement("EnableMotor", ljd.MotorEnabled);
WriteElement("LocalAnchorA", ljd.LocalAnchorA);
WriteElement("LocalAnchorB", ljd.LocalAnchorB);
WriteElement("MotorSpeed", ljd.MotorSpeed);
WriteElement("DampingRatio", ljd.DampingRatio);
WriteElement("MaxMotorTorque", ljd.MaxMotorTorque);
WriteElement("FrequencyHz", ljd.Frequency);
WriteElement("LocalXAxis", ljd.LocalXAxis);
}
break;
case JointType.Prismatic:
{
PrismaticJoint pjd = (PrismaticJoint)joint;
//NOTE: Does not conform with Box2DScene
WriteElement("EnableLimit", pjd.LimitEnabled);
WriteElement("EnableMotor", pjd.MotorEnabled);
WriteElement("LocalAnchorA", pjd.LocalAnchorA);
WriteElement("LocalAnchorB", pjd.LocalAnchorB);
WriteElement("LocalXAxis1", pjd.LocalXAxis1);
WriteElement("LowerTranslation", pjd.LowerLimit);
WriteElement("UpperTranslation", pjd.UpperLimit);
WriteElement("MaxMotorForce", pjd.MaxMotorForce);
WriteElement("MotorSpeed", pjd.MotorSpeed);
}
break;
case JointType.Pulley:
{
PulleyJoint pjd = (PulleyJoint)joint;
WriteElement("GroundAnchorA", pjd.GroundAnchorA);
WriteElement("GroundAnchorB", pjd.GroundAnchorB);
WriteElement("LengthA", pjd.LengthA);
WriteElement("LengthB", pjd.LengthB);
WriteElement("LocalAnchorA", pjd.LocalAnchorA);
WriteElement("LocalAnchorB", pjd.LocalAnchorB);
WriteElement("MaxLengthA", pjd.MaxLengthA);
WriteElement("MaxLengthB", pjd.MaxLengthB);
WriteElement("Ratio", pjd.Ratio);
}
break;
case JointType.Revolute:
{
RevoluteJoint rjd = (RevoluteJoint)joint;
WriteElement("EnableLimit", rjd.LimitEnabled);
WriteElement("EnableMotor", rjd.MotorEnabled);
WriteElement("LocalAnchorA", rjd.LocalAnchorA);
WriteElement("LocalAnchorB", rjd.LocalAnchorB);
WriteElement("LowerAngle", rjd.LowerLimit);
WriteElement("MaxMotorTorque", rjd.MaxMotorTorque);
WriteElement("MotorSpeed", rjd.MotorSpeed);
WriteElement("ReferenceAngle", rjd.ReferenceAngle);
WriteElement("UpperAngle", rjd.UpperLimit);
}
break;
case JointType.Weld:
{
WeldJoint wjd = (WeldJoint)joint;
WriteElement("LocalAnchorA", wjd.LocalAnchorA);
WriteElement("LocalAnchorB", wjd.LocalAnchorB);
}
break;
//
// Not part of Box2DScene
//
case JointType.Rope:
{
RopeJoint rjd = (RopeJoint)joint;
WriteElement("LocalAnchorA", rjd.LocalAnchorA);
WriteElement("LocalAnchorB", rjd.LocalAnchorB);
WriteElement("MaxLength", rjd.MaxLength);
}
break;
case JointType.Angle:
{
AngleJoint aj = (AngleJoint)joint;
WriteElement("BiasFactor", aj.BiasFactor);
WriteElement("MaxImpulse", aj.MaxImpulse);
WriteElement("Softness", aj.Softness);
WriteElement("TargetAngle", aj.TargetAngle);
}
break;
case JointType.Slider:
{
SliderJoint sliderJoint = (SliderJoint)joint;
WriteElement("DampingRatio", sliderJoint.DampingRatio);
WriteElement("FrequencyHz", sliderJoint.Frequency);
WriteElement("MaxLength", sliderJoint.MaxLength);
WriteElement("MinLength", sliderJoint.MinLength);
WriteElement("LocalAnchorA", sliderJoint.LocalAnchorA);
WriteElement("LocalAnchorB", sliderJoint.LocalAnchorB);
}
break;
default:
throw new Exception("Joint not supported");
}
_writer.WriteEndElement();
}
