/// <summary>
/// Creates the fixed revolute joint.
/// </summary>
/// <param name="world">The world.</param>
/// <param name="body">The body.</param>
/// <param name="bodyAnchor">The body anchor.</param>
/// <param name="worldAnchor">The world anchor.</param>
/// <returns></returns>
public static FixedRevoluteJoint CreateFixedRevoluteJoint(PhysicsWorld world, PhysicsBody body, Vector2 bodyAnchor,
Vector2 worldAnchor)
{
FixedRevoluteJoint fixedRevoluteJoint = new FixedRevoluteJoint(body, bodyAnchor, worldAnchor);
world.AddJoint(fixedRevoluteJoint);
return fixedRevoluteJoint;
}
/// <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;
}