import { Object3D, Raycaster, Face3, Vector3, Vector2, Mesh } from "three";
import { Viewer } from ".";

interface Intersect
{
    distance: number;
    face: Face3;
    faceIndex: number;
    object: Object3D;
    point: Vector3;
    uv: Vector2;
}


/**
 * 点选
 * 
 * @export
 * @param {Viewer} view 
 * @param {number} ptx 
 * @param {number} pty 
 * @returns {(Mesh | undefined)} 
 */
export function PointPick(view: Viewer, ptx: number, pty: number): Mesh | undefined
{
    let raycaster = new Raycaster();
    raycaster.setFromCamera({
        x: (ptx / view._Width) * 2 - 1,   //-1 到 1  所以 (x-(w/2))/(w/2) =>
        y: - (pty / view._Height) * 2 + 1 //y轴相反
    }, view.m_Camera.Camera);

    //https://github.com/mrdoob/three.js/issues/14128
    raycaster.ray.origin.set((ptx / view._Width) * 2 - 1, - (pty / view._Height) * 2 + 1, -1).unproject(view.m_Camera.Camera);


    let minDis = Infinity;
    let minObj = undefined;

    view.m_Scene.children.forEach(obj =>
    {
        if (obj instanceof Mesh)
        {
            let intersects: Intersect[] = [];
            obj.raycast(raycaster, intersects);

            for (let i of intersects)
            {
                if (i.distance < minDis)
                {
                    minObj = obj;
                    minDis = i.distance;
                }
            }
        }
    });

    return minObj;
}