CCWheelJoint.js

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var PTM_RATIO = require('../CCPhysicsTypes').PTM_RATIO;
var ANGLE_TO_PHYSICS_ANGLE = require('../CCPhysicsTypes').ANGLE_TO_PHYSICS_ANGLE;

/**
 * !#en
 * A wheel joint. This joint provides two degrees of freedom: translation
 * along an axis fixed in bodyA and rotation in the plane. You can use a joint motor to drive
 * the rotation or to model rotational friction.
 * This joint is designed for vehicle suspensions.
 * !#zh
 * 轮子关节提供两个维度的自由度：旋转和沿着指定方向上位置的移动。
 * 你可以通过开启关节马达来使用马达驱动刚体的旋转。
 * 轮组关节是专门为机动车类型设计的。
 * @class WheelJoint
 * @extends Joint
 */
var WheelJoint = cc.Class({
    name: 'cc.WheelJoint',
    extends: cc.Joint,
    
    editor: CC_EDITOR && {
        inspector: 'packages://inspector/inspectors/comps/physics/joint.js',
        help: 'i18n:COMPONENT.help_url.joint-component',
        menu: 'i18n:MAIN_MENU.component.physics/Joint/Wheel',
    },

    properties: {
        _maxMotorTorque: 0,
        _motorSpeed: 0,
        _enableMotor: false,
        
        _frequency: 2,
        _dampingRatio: 0.7,

        /**
         * !#en
         * The local joint axis relative to rigidbody.
         * !#zh
         * 指定刚体可以移动的方向。
         * @property {Vec2} localAxisA
         * @default cc.v2(1, 0)
         */
        localAxisA: {
            default: cc.v2(1, 0),
            tooltip: CC_DEV && 'i18n:COMPONENT.physics.physics_collider.localAxisA'
        },

        /**
         * !#en
         * The maxium torque can be applied to rigidbody to rearch the target motor speed.
         * !#zh
         * 可以施加到刚体的最大扭矩。
         * @property {Number} maxMotorTorque
         * @default 0
         */
        maxMotorTorque: {
            tooltip: CC_DEV && 'i18n:COMPONENT.physics.physics_collider.maxMotorTorque',            
            get: function () {
                return this._maxMotorTorque;
            },
            set: function (value) {
                this._maxMotorTorque = value;
                if (this._joint) {
                    this._joint.SetMaxMotorTorque(value);
                }
            }
        },

        /**
         * !#en
         * The expected motor speed.
         * !#zh
         * 期望的马达速度。
         * @property {Number} motorSpeed
         * @default 0
         */
        motorSpeed: {
            tooltip: CC_DEV && 'i18n:COMPONENT.physics.physics_collider.motorSpeed',
            get: function () {
                return this._motorSpeed;
            },
            set: function (value) {
                this._motorSpeed = value;
                if (this._joint) {
                    this._joint.SetMotorSpeed(value * ANGLE_TO_PHYSICS_ANGLE);
                }
            }
        },

        /**
         * !#en
         * Enable joint motor?
         * !#zh
         * 是否开启关节马达？
         * @property {Boolean} enableMotor
         * @default false
         */
        enableMotor: {
            tooltip: CC_DEV && 'i18n:COMPONENT.physics.physics_collider.enableMotor',            
            get: function () {
                return this._enableMotor;
            },
            set: function (value) {
                this._enableMotor = value;
                if (this._joint) {
                    this._joint.EnableMotor(value);
                }
            }
        },

        /**
         * !#en
         * The spring frequency.
         * !#zh
         * 弹性系数。
         * @property {Number} frequency
         * @default 0
         */
        frequency: {
            tooltip: CC_DEV && 'i18n:COMPONENT.physics.physics_collider.frequency',
            get: function () {
                return this._frequency;
            },
            set: function (value) {
                this._frequency = value;
                if (this._joint) {
                    this._joint.SetSpringFrequencyHz(value);
                }
            }
        },

        /**
         * !#en
         * The damping ratio.
         * !#zh
         * 阻尼，表示关节变形后，恢复到初始状态受到的阻力。
         * @property {Number} dampingRatio
         * @default 0
         */
        dampingRatio: {
            tooltip: CC_DEV && 'i18n:COMPONENT.physics.physics_collider.dampingRatio',            
            get: function () {
                return this._dampingRatio;
            },
            set: function (value) {
                this._dampingRatio = value;
                if (this._joint) {
                    this._joint.SetDampingRatio(value);
                }
            }
        }
    },

    _createJointDef: function () {
        var def = new b2.WheelJointDef();
        def.localAnchorA = new b2.Vec2(this.anchor.x/PTM_RATIO, this.anchor.y/PTM_RATIO);
        def.localAnchorB = new b2.Vec2(this.connectedAnchor.x/PTM_RATIO, this.connectedAnchor.y/PTM_RATIO);
        
        def.localAxisA = new b2.Vec2(this.localAxisA.x, this.localAxisA.y);
        
        def.maxMotorTorque = this.maxMotorTorque;
        def.motorSpeed = this.motorSpeed * ANGLE_TO_PHYSICS_ANGLE;
        def.enableMotor = this.enableMotor;

        def.dampingRatio = this.dampingRatio;
        def.frequencyHz = this.frequency;

        return def;
    }
});

cc.WheelJoint = module.exports = WheelJoint;