Gizmos and handles

Learn scene drawing with OnDrawGizmos and Handles.

Scene Visualization with OnDrawGizmos

To draw invisible trigger areas, collision bounds, or directional vectors directly in the Scene view, the OnDrawGizmos() method is used. Methods like Gizmos.DrawWireSphere or Gizmos.DrawLine render visual debugging guides.

void OnDrawGizmos()
{
    Gizmos.color = Color.yellow;
    Gizmos.DrawWireSphere(transform.position, 5f);
}

Interactive Scene Tools with Handles

While the Gizmos class draws static visual shapes, the UnityEditor.Handles class provides interactive handles (position arrows, sliders, rotation discs) draggable with the mouse in the Scene view. These controls are configured inside OnSceneGUI().

// Interactive draggable handle point with Handles
Handles.PositionHandle(position, Quaternion.identity);

Exercise Gizmo Sphere Draw Simulation

Inside the DrawGizmo(float yaricap) method, execute Debug.Log("Gizmo kure: " + yaricap);.

Show example solution

using System;

public static class Debug
{
    public static void Log(object message) => Console.WriteLine(message);
}

public class Program
{
    public static void DrawGizmo(float yaricap)
    {
        Debug.Log("Gizmo kure: " + yaricap);
    }

    public static void Main()
    {
        DrawGizmo(5f);
    }
}

Test yourself

Which method in Unity ensures gizmos are drawn in the Scene view only when the object is actively selected?
- OnDrawGizmosSelected
- OnRenderObject
- OnDrawGizmos
- OnSceneGUI
Show answer

OnDrawGizmosSelected — The OnDrawGizmosSelected method executes only while the GameObject hosting the component is actively selected.
Gizmo Draw Method
```
void ____() {}
```
Show answer
```
void OnDrawGizmos() {}
```
Gizmo and Handle Terminology

OnDrawGizmos

Draws visual guides in Scene view
Gizmos.color

Color of visual guide lines to draw
Handles

Interactive 3D handles in Scene view
OnSceneGUI

Method where custom handles are drawn

Next lesson: Summary - Custom tool

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