the-world-engine/dist/esm/box2d.ts/build/dynamics/b2_joint.js

three.js based, unity like game engine for browser

import { b2Maybe, b2_pi } from "../common/b2_settings.js";

import { b2Vec2 } from "../common/b2_math.js";

import { b2Color } from "../common/b2_draw.js";

export var b2JointType;

(function(t) {
    t[t["e_unknownJoint"] = 0] = "e_unknownJoint";
    t[t["e_revoluteJoint"] = 1] = "e_revoluteJoint";
    t[t["e_prismaticJoint"] = 2] = "e_prismaticJoint";
    t[t["e_distanceJoint"] = 3] = "e_distanceJoint";
    t[t["e_pulleyJoint"] = 4] = "e_pulleyJoint";
    t[t["e_mouseJoint"] = 5] = "e_mouseJoint";
    t[t["e_gearJoint"] = 6] = "e_gearJoint";
    t[t["e_wheelJoint"] = 7] = "e_wheelJoint";
    t[t["e_weldJoint"] = 8] = "e_weldJoint";
    t[t["e_frictionJoint"] = 9] = "e_frictionJoint";
    t[t["e_ropeJoint"] = 10] = "e_ropeJoint";
    t[t["e_motorJoint"] = 11] = "e_motorJoint";
    t[t["e_areaJoint"] = 12] = "e_areaJoint";
})(b2JointType || (b2JointType = {}));

export class b2Jacobian {
    constructor() {
        this.linear = new b2Vec2;
        this.angularA = 0;
        this.angularB = 0;
    }
    SetZero() {
        this.linear.SetZero();
        this.angularA = 0;
        this.angularB = 0;
        return this;
    }
    Set(t, i, e) {
        this.linear.Copy(t);
        this.angularA = i;
        this.angularB = e;
        return this;
    }
}

export class b2JointEdge {
    constructor(t) {
        this._other = null;
        this.prev = null;
        this.next = null;
        this.joint = t;
    }
    get other() {
        if (this._other === null) {
            throw new Error;
        }
        return this._other;
    }
    set other(t) {
        if (this._other !== null) {
            throw new Error;
        }
        this._other = t;
    }
    Reset() {
        this._other = null;
        this.prev = null;
        this.next = null;
    }
}

export class b2JointDef {
    constructor(t) {
        this.type = b2JointType.e_unknownJoint;
        this.userData = null;
        this.collideConnected = false;
        this.type = t;
    }
}

export function b2LinearStiffness(t, i, e, s, n) {
    const o = s.GetMass();
    const r = n.GetMass();
    let h;
    if (o > 0 && r > 0) {
        h = o * r / (o + r);
    } else if (o > 0) {
        h = o;
    } else {
        h = r;
    }
    const l = 2 * b2_pi * i;
    t.stiffness = h * l * l;
    t.damping = 2 * h * e * l;
}

export function b2AngularStiffness(t, i, e, s, n) {
    const o = s.GetInertia();
    const r = n.GetInertia();
    let h;
    if (o > 0 && r > 0) {
        h = o * r / (o + r);
    } else if (o > 0) {
        h = o;
    } else {
        h = r;
    }
    const l = 2 * b2_pi * i;
    t.stiffness = h * l * l;
    t.damping = 2 * h * e * l;
}

export class b2Joint {
    constructor(t) {
        this.m_type = b2JointType.e_unknownJoint;
        this.m_prev = null;
        this.m_next = null;
        this.m_edgeA = new b2JointEdge(this);
        this.m_edgeB = new b2JointEdge(this);
        this.m_index = 0;
        this.m_islandFlag = false;
        this.m_collideConnected = false;
        this.m_userData = null;
        this.m_type = t.type;
        this.m_edgeA.other = t.bodyB;
        this.m_edgeB.other = t.bodyA;
        this.m_bodyA = t.bodyA;
        this.m_bodyB = t.bodyB;
        this.m_collideConnected = b2Maybe(t.collideConnected, false);
        this.m_userData = b2Maybe(t.userData, null);
    }
    GetType() {
        return this.m_type;
    }
    GetBodyA() {
        return this.m_bodyA;
    }
    GetBodyB() {
        return this.m_bodyB;
    }
    GetNext() {
        return this.m_next;
    }
    GetUserData() {
        return this.m_userData;
    }
    SetUserData(t) {
        this.m_userData = t;
    }
    IsEnabled() {
        return this.m_bodyA.IsEnabled() && this.m_bodyB.IsEnabled();
    }
    GetCollideConnected() {
        return this.m_collideConnected;
    }
    Dump(t) {
        t("// Dump is not supported for this joint type.\n");
    }
    ShiftOrigin(t) {}
    Draw(t) {
        const i = this.m_bodyA.GetTransform();
        const e = this.m_bodyB.GetTransform();
        const s = i.p;
        const n = e.p;
        const o = this.GetAnchorA(b2Joint.Draw_s_p1);
        const r = this.GetAnchorB(b2Joint.Draw_s_p2);
        const h = b2Joint.Draw_s_color.SetRGB(.5, .8, .8);
        switch (this.m_type) {
          case b2JointType.e_distanceJoint:
            t.DrawSegment(o, r, h);
            break;

          case b2JointType.e_pulleyJoint:
            {
                const i = this;
                const e = i.GetGroundAnchorA();
                const s = i.GetGroundAnchorB();
                t.DrawSegment(e, o, h);
                t.DrawSegment(s, r, h);
                t.DrawSegment(e, s, h);
            }
            break;

          case b2JointType.e_mouseJoint:
            {
                const i = b2Joint.Draw_s_c;
                i.Set(0, 1, 0);
                t.DrawPoint(o, 4, i);
                t.DrawPoint(r, 4, i);
                i.Set(.8, .8, .8);
                t.DrawSegment(o, r, i);
            }
            break;

          default:
            t.DrawSegment(s, o, h);
            t.DrawSegment(o, r, h);
            t.DrawSegment(n, r, h);
        }
    }
}

b2Joint.Draw_s_p1 = new b2Vec2;

b2Joint.Draw_s_p2 = new b2Vec2;

b2Joint.Draw_s_color = new b2Color(.5, .8, .8);

b2Joint.Draw_s_c = new b2Color;