Show Mesh Vertex Normals

This snippet allows you to add lines showing the normals for each vertex of a mesh. The colour and size of the lines can be set.

function showNormals(mesh, size, color, sc) {
    var normals = mesh.getVerticesData(BABYLON.VertexBuffer.NormalKind);
    var positions = mesh.getVerticesData(BABYLON.VertexBuffer.PositionKind);
    color = color || BABYLON.Color3.White();
    sc = sc || scene;
    size = size || 1;

    var lines = [];
    for (var i = 0; i < normals.length; i += 3) {
        var v1 = BABYLON.Vector3.FromArray(positions, i);
        var v2 = v1.add(BABYLON.Vector3.FromArray(normals, i).scaleInPlace(size));
        lines.push([v1.add(mesh.position), v2.add(mesh.position)]);
    }
    var normalLines = BABYLON.MeshBuilder.CreateLineSystem("normalLines", {lines: lines}, sc);
    normalLines.color = color;
    return normalLines;
}

Playground

Playground Example -