114 lines
2.8 KiB
Dart
114 lines
2.8 KiB
Dart
part of skysprites;
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abstract class PhysicsJoint {
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PhysicsJoint(this.bodyA, this.bodyB) {
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bodyA._joints.add(this);
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bodyB._joints.add(this);
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}
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PhysicsBody bodyA;
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PhysicsBody bodyB;
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bool _active = true;
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box2d.Joint _joint;
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PhysicsNode _physicsNode;
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void _completeCreation() {
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if (bodyA._attached && bodyB._attached) {
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_attach(bodyA._physicsNode);
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}
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}
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void _attach(PhysicsNode physicsNode) {
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if (_joint == null) {
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_physicsNode = physicsNode;
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_joint = _createB2Joint(physicsNode);
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}
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}
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void _detach() {
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if (_joint != null && _active) {
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_physicsNode.b2World.destroyJoint(_joint);
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_joint = null;
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}
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_active = false;
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}
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box2d.Joint _createB2Joint(PhysicsNode physicsNode);
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}
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class PhysicsJointRevolute extends PhysicsJoint {
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PhysicsJointRevolute(
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PhysicsBody bodyA,
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PhysicsBody bodyB,
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this.worldAnchor, {
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double lowerAngle: 0.0,
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double upperAngle: 0.0,
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bool enableLimit: false
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}) : super(bodyA, bodyB) {
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this.lowerAngle = lowerAngle;
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this.upperAngle = upperAngle;
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this.enableLimit = enableLimit;
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_completeCreation();
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}
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Point worldAnchor;
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double lowerAngle;
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double upperAngle;
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bool enableLimit;
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box2d.Joint _createB2Joint(PhysicsNode physicsNode) {
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// Create Joint Definition
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Vector2 vecAnchor = new Vector2(
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worldAnchor.x / physicsNode.b2WorldToNodeConversionFactor,
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worldAnchor.y / physicsNode.b2WorldToNodeConversionFactor
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);
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box2d.RevoluteJointDef b2Def = new box2d.RevoluteJointDef();
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b2Def.initialize(bodyA._body, bodyB._body, vecAnchor);
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b2Def.enableLimit = enableLimit;
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b2Def.lowerAngle = lowerAngle;
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b2Def.upperAngle = upperAngle;
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// Create joint
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return physicsNode.b2World.createJoint(b2Def);
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}
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}
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class PhysicsJointPrismatic extends PhysicsJoint {
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PhysicsJointPrismatic(
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PhysicsBody bodyA,
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PhysicsBody bodyB,
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this.axis) : super(bodyA, bodyB) {
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_completeCreation();
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}
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Offset axis;
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box2d.Joint _createB2Joint(PhysicsNode physicsNode) {
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box2d.PrismaticJointDef b2Def = new box2d.PrismaticJointDef();
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b2Def.initialize(bodyA._body, bodyB._body, bodyA._body.position, new Vector2(axis.dx, axis.dy));
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return physicsNode.b2World.createJoint(b2Def);
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}
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}
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class PhysicsJointWeld extends PhysicsJoint {
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PhysicsJointWeld(
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PhysicsBody bodyA,
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PhysicsBody bodyB) : super(bodyA, bodyB) {
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_completeCreation();
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}
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box2d.Joint _createB2Joint(PhysicsNode physicsNode) {
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box2d.WeldJointDef b2Def = new box2d.WeldJointDef();
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Vector2 middle = new Vector2(
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(bodyA._body.position.x + bodyB._body.position.x) / 2.0,
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(bodyA._body.position.y + bodyB._body.position.y) / 2.0
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);
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b2Def.initialize(bodyA._body, bodyB._body, middle);
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return physicsNode.b2World.createJoint(b2Def);
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}
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}
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