Enable an outline on mouse hover or click

✅ Linework Sample
This sample explains how to enable/disable an outline when hovering over an object or when clicking on it.

✅ Prerequisites
1. Event System

Make sure that there is an EventSystem in your scene. If not, use Create > UI > Event System to create one.

2. Physics Raycaster

Make sure that your camera has a Physics Raycaster component added to it.

Jump to heading Steps

Assign this script component to any GameObject that you want to have an outline. The GameObject should have a Collider and a Mesh Renderer. The core functionality of the script is changing the rendering layer of the selected object's Mesh Renderer to be the one that the outline is activated for.

Unity 2022

using UnityEngine;  
using UnityEngine.EventSystems;  
using Linework.Common.Attributes;
  
public class Outline : MonoBehaviour, IPointerEnterHandler, IPointerExitHandler, IPointerClickHandler  
{  
    [SerializeField] [RenderingLayerMask] private int outlineLayer;
    [SerializeField] private Activate activate = Activate.OnHover;  
  
    private Renderer[] renderers;  
    private uint originalLayer;
    private bool isOutlineActive;
  
    private enum Activate  
    {  
        OnHover,  
        OnClick  
    }  
  
    private void Start()  
    {        
	    renderers = TryGetComponent<Renderer>(out var meshRenderer)  
            ? new[] {meshRenderer}  
            : GetComponentsInChildren<Renderer>();  
        originalLayer = renderers[0].renderingLayerMask;  
    }  
    
    public void OnPointerEnter(PointerEventData eventData)  
    {        
	    if (activate != Activate.OnHover) return;  
        SetOutline(true);  
    }  
    
    public void OnPointerExit(PointerEventData eventData)  
    {        
	    if (activate != Activate.OnHover) return;  
        SetOutline(false);  
    }    
    
    public void OnPointerClick(PointerEventData eventData)  
    {        
	    if (activate != Activate.OnClick) return;  
        isOutlineActive = !isOutlineActive;  
        SetOutline(isOutlineActive);  
    }    
    
    private void SetOutline(bool enable)  
    {        
	    foreach (var rend in renderers)  
        {            
			rend.renderingLayerMask = enable 
	        ? originalLayer | 1u << outlineLayer - 1 
	        : originalLayer;  
        }    
	}
}

Unity 6

using UnityEngine;  
using UnityEngine.EventSystems;  
  
public class Outline : MonoBehaviour, IPointerEnterHandler, IPointerExitHandler, IPointerClickHandler  
{  
    [SerializeField] private RenderingLayerMask outlineLayer;
    [SerializeField] private Activate activate = Activate.OnHover;  
  
    private Renderer[] renderers;  
    private uint originalLayer;  
    private bool isOutlineActive;  
  
    private enum Activate  
    {  
        OnHover,  
        OnClick  
    }  
  
    private void Start()  
    {        
	    renderers = TryGetComponent<Renderer>(out var meshRenderer)  
            ? new[] {meshRenderer}  
            : GetComponentsInChildren<Renderer>();  
        originalLayer = renderers[0].renderingLayerMask;  
    }  
    
    public void OnPointerEnter(PointerEventData eventData)  
    {        
	    if (activate != Activate.OnHover) return;  
        SetOutline(true);  
    }  
    
    public void OnPointerExit(PointerEventData eventData)  
    {        
	    if (activate != Activate.OnHover) return;  
        SetOutline(false);  
    }    
    
    public void OnPointerClick(PointerEventData eventData)  
    {        
	    if (activate != Activate.OnClick) return;  
        isOutlineActive = !isOutlineActive;  
        SetOutline(isOutlineActive);  
    }    
    
    private void SetOutline(bool enable)  
    {        
	    foreach (var rend in renderers)  
        {            
	        rend.renderingLayerMask = enable 
	        ? originalLayer | outlineLayer 
	        : originalLayer; 
        }    
	}
}

Active an outline on mouse hover or click-3

❗ Odin Inspector
There is an issue in Odin Inspector with the way it renders RenderingLayerMask fields in the inspector. This should be fixed in a later update of Odin. For now, you can force the field to be drawn by Unity to see it correctly.

Select the Outline Layer in the inspector to be the same as the Layer that you have configured for the outline.

Active an outline on mouse hover or click-1

Using the Activate option, you can switch between activating the outline On Hover or On Click.

Jump to heading Issues?

Check the checklist with requirements above
check if a collider may be obscuring your selectable game object
if the collider on the selectable object is a trigger, verify that Queries Hit Triggers is enabled in the physics settings
check Raycaster Event Mask vs gameobject's layer mask

Enable an outline on mouse hover or click

Jump to heading # Steps

Jump to heading # Issues?

Jump to heading Steps

Jump to heading Issues?