Documentation

Calculate pointer world position

https://github.com/needle-tools/needle-engine-support/assets/30328735/92404e43-9d45-4ee2-a018-fb00412b6bd5

import { Behaviour, serializable, setWorldPosition } from "@needle-tools/engine";
import { Object3D, Vector3 } from "three";

const vector1 = new Vector3();
const vector2 = new Vector3();

export class PointerFollower extends Behaviour {

    @serializable(Object3D)
    target?: Object3D;

    @serializable()
    offset: number = 10;

    update(): void {
        const cam = this.context.mainCamera;
        const input = this.context.input;

        if(!this.target || !cam)
            return;

        // get relative mouse position, in range -1 to 1
        const mouse = input.mousePositionRC;

        // get world position of mouse on the near plane
        vector1.set(mouse.x, mouse.y, -1).unproject(cam!);

        // caulculate direction from camera to world mouse
        vector2.copy(vector1).sub(cam.position).normalize();

        // offset it to the wanted distance
        vector1.addScaledVector(vector2, this.offset);

        // apply the result
        setWorldPosition(this.target, vector1);
    }
}