Hi, what's wrong with my roaming code? Thank you.

[shenshengyi]

Hi, I want to realize roaming along the specified path. The following is my roaming code, but the scene is just a little bit moving, can you help me to point out which place is wrong? Thank you.

`class TestRoaming implements Animator {
private pathIndex = 0;
protected _lastMotionTime = 0;
private _navigateMotion: NavigateMotion;
protected readonly _lastPtView = new Point3d();
private _initialized = false;
protected _deadZone = 36;
private lineStr: LineString3d;
private frac: number = 0.1;
protected readonly _anchorPtView = new Point3d();
private lastP = new Point3d();
public constructor(public viewport: ScreenViewport, public paths: Point3d[]) {
this._navigateMotion = new NavigateMotion(viewport);
this.lineStr = LineString3d.create(paths);
this.lastP = this.paths[0];
}

protected getElapsedTime(): number {
const prev = this._lastMotionTime;
this._lastMotionTime = Date.now();
return Geometry.clamp(this._lastMotionTime - prev, 0, 1000) / 1000;
}
interrupt(): void {}
protected getDirection(): Vector3d | undefined {
this.frac += 0.05;
const p = this.lineStr.fractionToPoint(this.frac);
let dir = this.lastP.vectorTo(p);
this.lastP = p;
dir.z = 0;
// return dir.magnitudeSquared() < this._deadZone ? undefined : dir; // dead zone around starting point
return dir;
}
getInputVector(): Vector3d | undefined {
const dir = this.getDirection();
if (undefined === dir) return undefined;
const viewRect = this.viewport!.viewRect;
return new Vector3d(
dir.x * (2.0 / viewRect.width),
dir.y * (2.0 / viewRect.height)
);
}
getNavigateMotion(elapsedTime: number): NavigateMotion | undefined {
const input = this.getInputVector();
if (undefined === input) return undefined;

const motion = this._navigateMotion;
motion.init(elapsedTime);

switch (this.getNavigateMode()) {
  case NavigateMode.Pan:
    input.scale(this.getMaxLinearVelocity(), input);
    motion.pan(input.x, input.y);
    break;
  case NavigateMode.Look:
    input.scale(-this.getMaxAngularVelocity(), input);
    motion.look(input.x, input.y);
    break;
  case NavigateMode.Travel:
    motion.travel(
      -input.x * this.getMaxAngularVelocity(),
      0,
      -input.y * this.getMaxLinearVelocity(),
      true
    );
    break;
}

return motion;

}
public getHandleCursor() {
return IModelApp.viewManager.walkCursor;
}
public getMaxLinearVelocity() {
return ToolSettings.walkVelocity;
}
public getMaxAngularVelocity() {
return Math.PI / 4;
}

public getNavigateMode(): NavigateMode {
return NavigateMode.Travel;
}
// called in animation loop
public animate(): boolean {
if (this.frac >= 1) {
return true;
}
const t = this.getElapsedTime();
const motion = this.getNavigateMotion(t);
if (undefined !== motion) {
const vp = this.viewport;
const frust = vp.getWorldFrustum();
frust.multiply(motion.transform);
vp.setupViewFromFrustum(frust);
}
return false;
}
}`

[shenshengyi]

It's OK