I want to update a LinesMesh by the following code:
import * as BABYLON from "@babylonjs/core";
import { Vector3 } from "@babylonjs/core";
export class Box {
private scene: BABYLON.Scene;
// @ts-ignore
private xhi: number;
private yhi: number;
private zhi: number;
private xlo: number;
private ylo: number;
private zlo: number;
private xy: number;
private xz: number;
private yz: number;
private Lx: number;
private Ly: number;
private Lz: number;
private box_mesh: BABYLON.LinesMesh;
constructor(scene: BABYLON.Scene, xhi: number, yhi: number, zhi: number, xlo: number, ylo: number, zlo: number, xy: number, xz: number, yz: number) {
this.scene = scene;
const points1 = this.computeBoxVertries(xhi, yhi, zhi, xlo, ylo, zlo, xy, xz, yz);
// create box mesh
this.box_mesh = BABYLON.MeshBuilder.CreateLines("box", {points: points1}, scene);
}
private computeBoxVertries(xhi: number, yhi: number, zhi: number, xlo: number, ylo: number, zlo: number, xy: number, xz: number, yz: number) {
this.xhi = xhi;
this.yhi = yhi;
this.zhi = zhi;
this.xlo = xlo;
this.ylo = ylo;
this.zlo = zlo;
this.xy = xy;
this.xz = xz;
this.yz = yz;
this.Lx = xhi - xlo;
this.Ly = yhi - ylo;
this.Lz = zhi - zlo;
return [
new Vector3(xlo, ylo, zlo), // (0, 0, 0)
new Vector3(xhi, ylo, zlo), // (1, 0, 0)
new Vector3(xhi+xy, yhi, zlo), // (1, 1, 0)
new Vector3(xlo+xy, yhi, zlo), // (0, 1, 0)
new Vector3(xlo, ylo, zlo), // (0, 0, 0)
new Vector3(xlo+xz, ylo+yz, zhi), // (0, 0, 1)
new Vector3(xhi+xz, ylo+yz, zhi), // (1, 0, 1)
new Vector3(xhi+xz+xy, yhi+yz, zhi), // (1, 1, 1)
new Vector3(xlo+xz+xy, yhi+yz, zhi), // (0, 1, 1)
new Vector3(xlo+xz, ylo+yz, zhi), // (0, 0, 1)
new Vector3(xhi+xz, ylo+yz, zhi), // (1, 0, 1)
new Vector3(xhi, ylo, zlo), // (1, 0, 0)
new Vector3(xhi+xy, yhi, zlo), // (1, 1, 0)
new Vector3(xhi+xz+xy, yhi+yz, zhi), // (1, 1, 1)
new Vector3(xlo+xz+xy, yhi+yz, zhi), // (0, 1, 1)
new Vector3(xlo+xy, yhi, zlo), // (0, 1, 0)
];
}
public update(xhi: number, yhi: number, zhi: number, xlo: number, ylo: number, zlo: number, xy: number, xz: number, yz: number) {
// change the vertices positions of an existing mesh.
// Indices remain unchanged
let points = this.computeBoxVertries(xhi, yhi, zhi, xlo, ylo, zlo, xy, xz, yz);
this.box_mesh = BABYLON.MeshBuilder.CreateLines("box", {points: points, instance: this.box_mesh});
}
}
I find that if I use this.box_mesh, it takes no effects, but I use let box_mesh and instance is box_mesh (not class member), it is ok? Can someone tell me what’s the difference?