Blog: Draw Bounding Box

DrawBoundingBox.cs

using UnityEngine;
using static UnityEditor.Handles;
using static UnityEngine.Color;
using static UnityEngine.Gizmos;

[ExecuteAlways]
[RequireComponent(typeof(Renderer))]
public class MarkCenterAndExtents : MonoBehaviour
{
    private const float RADIUS = 0.02f;
    private GUIStyle _labelStyle;
    private Renderer _renderer;

    private void Start()
    {
        _renderer = GetComponent<Renderer>();
    }

    private void OnDrawGizmos()
    {
        var bounds = _renderer.bounds;
        Vector2 center = bounds.center;
        DrawPoints(center, bounds);
    }

    private void DrawPoints(Vector3 center, Bounds bounds)
    {
        Gizmos.color = white;
        DrawSphere(center, RADIUS);
        Gizmos.color = red;
        var extents = bounds.extents;
        var topRight = center + extents;
        var topLeft = center + new Vector3(-extents.x, extents.y);
        var bottomRight = center + new Vector3(extents.x, -extents.y);
        var bottomLeft = center - extents;

        Gizmos.color = blue;
        DrawSphere(topRight, RADIUS);
        DrawSphere(topLeft, RADIUS);
        DrawSphere(bottomRight, RADIUS);
        DrawSphere(bottomLeft, RADIUS);
        DrawLines(new[] {topRight, topLeft, bottomLeft, bottomRight}, new[] {0, 1, 1, 2, 2, 3, 3, 0});
    }
}