Display Vertex Normals

import { VertexBuffer } from "@babylonjs/core/Buffers/buffer";
import { Color3 } from "@babylonjs/core/Maths/math.color";
import { Vector3 } from "@babylonjs/core/Maths/math.vector";
import { MeshBuilder } from "@babylonjs/core/Meshes/meshBuilder";
function showNormals(mesh, size, color, sc) {
    var normals = mesh.getVerticesData(VertexBuffer.NormalKind);
    var positions = mesh.getVerticesData(VertexBuffer.PositionKind);
    color = color || Color3.White();
    sc = sc || scene;
    size = size || 1;
    var lines = [];
    for (let i = 0; i < normals.length; i += 3) {
        var v1 = Vector3.FromArray(positions, i);
        var v2 = v1.add(Vector3.FromArray(normals, i).scaleInPlace(size));
        lines.push([v1.add(mesh.position), v2.add(mesh.position)]);
    }
    var normalLines = MeshBuilder.CreateLineSystem("normalLines", { lines: lines }, sc);
    normalLines.color = color;
    return normalLines;
}