three-demo/src/navigator.ts

import { Object3D, Vector3 } from 'three';
import { ReeGame } from './index';

export class KeyPoint {
    point: Vector3 | Object3D = new Vector3();
    lookAt?: Vector3 | Object3D;

    constructor(p: Vector3 | Object3D, look?: Vector3 | Object3D) {
        this.point = p;
        this.lookAt = look;
    }
}

export class OrbitNavigator {
    private speed: number;
    private loop: boolean;
    private translateDelta: number;
    private target: Object3D;
    private points: KeyPoint[];
    private idxMax: number;
    private idxP0 = 0; // 当前下一个位置索引
    private p0: Vector3 = new Vector3(); //上一个关键点
    private p1: Vector3 = new Vector3(); //下一个关键点
    private lookAt: Vector3 | undefined;
    private direction: Vector3 = new Vector3(); //当前前进方向

    private vec: Vector3 = new Vector3();

    constructor(target: Object3D, points: KeyPoint[], speed: number, loop: boolean = true) {
        this.target = target;
        this.points = points || [];
        this.idxMax = points.length - 2;

        this.speed = speed;
        this.translateDelta = speed * 0.001;
        this.loop = loop;
    }

    start() {
        this.idxP0 = 0;
        this.calcDirection();

        this.target.position.set(this.p0.x, this.p0.y, this.p0.z);
        ReeGame.setUpdate(this.target, (obj: Object3D) => {
            this.update(obj);
        });
        console.log("start");

    }

    restart() {
        this.idxP0 = 0;
        this.calcDirection();

        this.target.position.set(this.p0.x, this.p0.y, this.p0.z);
    }
    private update(obj: Object3D) {

        if (obj.position.distanceTo(this.p1) <= 0.1) {
            this.idxP0++;
            this.calcDirection();
        }

        if(this.lookAt){
            obj.lookAt(this.lookAt);
        }
        obj.position.addScaledVector(this.direction, this.translateDelta);
    }

    private calcDirection() {
        if (this.idxP0 > this.idxMax) {
            if (this.loop) {
                this.restart();
            }
            else {
                this.direction = new Vector3(0, 0, 0);
                return;
            }
        }

        let p0 = this.points[this.idxP0].point;
        let p1 = this.points[this.idxP0 + 1].point;
        let lookAt = this.points[this.idxP0].lookAt;

        this.lookAt = lookAt && lookAt instanceof Vector3 ? lookAt : lookAt?.position;
        this.p0 = p0 instanceof Vector3 ? p0 : p0.position;
        this.p1 = p1 instanceof Vector3 ? p1 : p1.position;
        this.vec = this.vec.subVectors(this.p1, this.p0);
        this.direction = this.vec.normalize();


    }

}