How to do it...

To create a design-time snap-to-grid drawn by a Gizmo in the Scene window, follow these steps:

1. Create a new Unity 3D project.
2. In the Scene window, turn off the Skybox view (or simply toggle off all the visual settings) so that you have a plain background for your grid:

3. Updating the display and the child objects will be performed by a script class called GridGizmo. Create a new C# script class called GridGizmo that contains the following code:

     using UnityEngine;
 
     public class GridGizmo : MonoBehaviour {
         public int grid = 2;
 
         public void SetGrid(int grid) {
             this.grid = grid;
             SnapAllChildren();
         }
 
         public Color gridColor = Color.red; 
         public int numLines = 6;
         public int lineLength = 50;
 
         private void SnapAllChildren() {
             foreach (Transform child...