/// <inheritdoc />
protected override void PostStep()
{
if (Input.GetKeyDown(KeyCode.J))
{
if (_rope != null)
{
World.DestroyJoint(_rope);
_rope = null;
}
else
{
_rope = World.CreateJoint(_ropeDef);
}
}
DrawString("Press (j) to toggle the rope joint.");
if (_rope != null)
{
DrawString("Rope ON");
}
else
{
DrawString("Rope OFF");
}
}
/// <inheritdoc />
public override void JointDestroyed(Joint joint)
{
for (var i = 0; i < 8; ++i)
{
if (_joints[i] == joint)
{
_joints[i] = null;
break;
}
}
}
/// <inheritdoc />
/// <inheritdoc />
public override void OnKeyDown(KeyboardKeyEventArgs key)
{
if (key.Key == Key.J)
{
if (_rope != null)
{
World.DestroyJoint(_rope);
_rope = null;
}
else
{
_rope = World.CreateJoint(_ropeDef);
}
}
}
/// <inheritdoc />
/// <inheritdoc />
public override void OnKeyDown(KeyInputEventArgs keyInput)
{
if (keyInput.Key == KeyCodes.J)
{
if (_rope != null)
{
World.DestroyJoint(_rope);
_rope = null;
}
else
{
_rope = World.CreateJoint(_ropeDef);
}
}
}
/// <inheritdoc />
protected override void OnStep()
{
if (Input.GetKeyDown(KeyCode.J))
{
if (_rope != null)
{
World.DestroyJoint(_rope);
_rope = null;
}
else
{
_rope = World.CreateJoint(_ropeDef);
}
}
}
public RopeJoint()
{
Body ground;
{
var bd = new BodyDef();
ground = World.CreateBody(bd);
var shape = new EdgeShape();
shape.SetTwoSided(new Vector2(-40.0f, 0.0f), new Vector2(40.0f, 0.0f));
ground.CreateFixture(shape, 0.0f);
}
{
var shape = new PolygonShape();
shape.SetAsBox(0.5f, 0.125f);
var fd = new FixtureDef();
fd.Shape = shape;
fd.Density = 20.0f;
fd.Friction = 0.2f;
var filter = fd.Filter;
filter.CategoryBits = 0x0001;
filter.MaskBits = 0xFFFF & ~0x0002;
fd.Filter = filter;
var jd = new RevoluteJointDef();
jd.CollideConnected = false;
const int N = 10;
const float y = 15.0f;
_ropeDef.LocalAnchorA.Set(0.0f, y);
var prevBody = ground;
for (var i = 0; i < N; ++i)
{
var bd = new BodyDef();
bd.BodyType = BodyType.DynamicBody;
bd.Position.Set(0.5f + 1.0f * i, y);
if (i == N - 1)
{
shape.SetAsBox(1.5f, 1.5f);
fd.Density = 100.0f;
filter = fd.Filter;
filter.CategoryBits = 0x0002;
fd.Filter = filter;
bd.Position.Set(1.0f * i, y);
bd.AngularDamping = 0.4f;
}
var body = World.CreateBody(bd);
body.CreateFixture(fd);
var anchor = new Vector2(i, y);
jd.Initialize(prevBody, body, anchor);
World.CreateJoint(jd);
prevBody = body;
}
_ropeDef.LocalAnchorB.SetZero();
var extraLength = 0.01f;
_ropeDef.MaxLength = N - 1.0f + extraLength;
_ropeDef.BodyB = prevBody;
}
{
_ropeDef.BodyA = ground;
_rope = World.CreateJoint(_ropeDef);
}
}
/// <inheritdoc />
public void Dispose()
{
Other = null;
Joint = null;
Node = null;
}
public GearJoint(GearJointDef def) : base(def)
{
_joint1 = def.Joint1;
_joint2 = def.Joint2;
_typeA = _joint1.JointType;
_typeB = _joint2.JointType;
Debug.Assert(_typeA == JointType.RevoluteJoint || _typeA == JointType.PrismaticJoint);
Debug.Assert(_typeB == JointType.RevoluteJoint || _typeB == JointType.PrismaticJoint);
Single coordinateA, coordinateB;
// TODO_ERIN there might be some problem with the joint edges in b2Joint.
_bodyC = _joint1.BodyA;
BodyA = _joint1.BodyB;
// Get geometry of joint1
var xfA = BodyA.Transform;
var aA = BodyA.Sweep.A;
var xfC = _bodyC.Transform;
var aC = _bodyC.Sweep.A;
if (_typeA == JointType.RevoluteJoint)
{
var revolute = (RevoluteJoint)def.Joint1;
_localAnchorC = revolute.LocalAnchorA;
_localAnchorA = revolute.LocalAnchorB;
_referenceAngleA = revolute.ReferenceAngle;
_localAxisC.SetZero();
coordinateA = aA - aC - _referenceAngleA;
}
else
{
var prismatic = (PrismaticJoint)def.Joint1;
_localAnchorC = prismatic.LocalAnchorA;
_localAnchorA = prismatic.LocalAnchorB;
_referenceAngleA = prismatic.ReferenceAngle;
_localAxisC = prismatic.LocalXAxisA;
var pC = _localAnchorC;
var pA = MathUtils.MulT(
xfC.Rotation,
MathUtils.Mul(xfA.Rotation, _localAnchorA) + (xfA.Position - xfC.Position));
coordinateA = MathUtils.Dot(pA - pC, _localAxisC);
}
_bodyD = _joint2.BodyA;
BodyB = _joint2.BodyB;
// Get geometry of joint2
var xfB = BodyB.Transform;
var aB = BodyB.Sweep.A;
var xfD = _bodyD.Transform;
var aD = _bodyD.Sweep.A;
if (_typeB == JointType.RevoluteJoint)
{
var revolute = (RevoluteJoint)def.Joint2;
_localAnchorD = revolute.LocalAnchorA;
_localAnchorB = revolute.LocalAnchorB;
_referenceAngleB = revolute.ReferenceAngle;
_localAxisD.SetZero();
coordinateB = aB - aD - _referenceAngleB;
}
else
{
var prismatic = (PrismaticJoint)def.Joint2;
_localAnchorD = prismatic.LocalAnchorA;
_localAnchorB = prismatic.LocalAnchorB;
_referenceAngleB = prismatic.ReferenceAngle;
_localAxisD = prismatic.LocalXAxisA;
var pD = _localAnchorD;
var pB = MathUtils.MulT(
xfD.Rotation,
MathUtils.Mul(xfB.Rotation, _localAnchorB) + (xfB.Position - xfD.Position));
coordinateB = MathUtils.Dot(pB - pD, _localAxisD);
}
_ratio = def.Ratio;
_constant = coordinateA + _ratio * coordinateB;
_impulse = 0.0f;
}
