How do you make an object not selectable in Unity?

Making an object not selectable in Unity can be achieved through several methods, ranging from simple editor settings to advanced scripting and shader modifications. The most direct approach often involves utilizing Unity's built-in editor tools, while more complex scenarios might require programming.

Here are the primary ways to make an object unselectable in Unity:

Preventing Selection in the Unity Editor

These methods are primarily used to manage object selection within the Unity editor's Scene view and Hierarchy, preventing accidental clicks or manipulations.

1. Locking a GameObject

One of the simplest and most common ways to prevent accidental selection and modification of a GameObject in the Unity Editor is to lock it. When locked, an object cannot be selected by clicking in the Scene view, nor can its transform or properties be edited in the Inspector.

• How to Lock:

  1. Select the GameObject(s) you wish to lock in the Hierarchy window.
  2. Click the small "lock" icon that appears next to the GameObject's name in the Inspector window (top right, near the GameObject name).
  3. Alternatively, you can toggle the lock state for multiple selected objects by right-clicking in the Hierarchy and choosing "Toggle Lock."

• Benefits:

  • Prevents accidental movement, rotation, scaling, or property changes.
  • Keeps important scene elements fixed while you work on other objects.

• Considerations: A locked object can still be selected by clicking its name directly in the Hierarchy, but its properties remain uneditable until unlocked.

2. Using Layers and Scene View Visibility

Unity's Layer system provides a powerful way to organize objects and control their visibility and pickability in the Scene view. By assigning objects to specific layers and then toggling the visibility of those layers, you can effectively make entire groups of objects unselectable.

• How to Use Layers for Selectability:

  1. Create a New Layer: Go to Layers -> Edit Layers... in the Inspector's top right dropdown. Add a new layer (e.g., "NonSelectableProps").
  2. Assign Objects to the Layer: Select the GameObject(s) you want to make unselectable. In the Inspector, next to the Layer dropdown, choose your newly created layer.
  3. Toggle Layer Visibility: In the Scene view's top toolbar, click the Layers dropdown. Deselect the checkbox next to your "NonSelectableProps" layer. This will hide objects on that layer and make them unselectable in the Scene view.

• Benefits:

  • Manages large groups of objects efficiently.
  • Great for complex scenes with environmental props or reference geometry.
  • Can also be used for physics collision filtering and camera rendering.

• Learn More: Refer to the official Unity Layers documentation.

3. Advanced Editor Control with HideFlags

For programmatic control over object behavior in the editor, Unity provides HideFlags. These flags allow you to modify how a GameObject appears and behaves in the Hierarchy, Inspector, and Scene view.

• HideFlags.NotEditable: Makes the object uneditable in the Inspector. While still selectable, its properties cannot be changed directly through the UI.

• HideFlags.HideInHierarchy: Hides the object from the Hierarchy window. It remains visible in the Scene view and selectable there, but is not listed in the Hierarchy.

• HideFlags.HideInInspector: Hides the object from the Inspector window.

• HideFlags.HideAndDontSave: The most powerful combination. Hides the object from both the Hierarchy and Inspector, and prevents it from being saved with the scene. Such objects are effectively invisible to the editor UI and generally unselectable by conventional means unless specifically queried via script.

• Example (C# Script):

  using UnityEngine;
  
  public class MakeObjectUnselectable : MonoBehaviour
  {
      void Start()
      {
          // Makes this GameObject uneditable in the Inspector
          // and hides it from the Hierarchy.
          gameObject.hideFlags = HideFlags.NotEditable | HideFlags.HideInHierarchy;
  
          // For the most extreme invisibility/unselectability in the editor
          // gameObject.hideFlags = HideFlags.HideAndDontSave;
      }
  
      // You might want an editor script to easily toggle this
      // or a button in the inspector for debugging purposes.
  }

• How to Use: Attach this script to the GameObject you wish to modify. When the game runs (or in the editor if ExecuteInEditMode is used), the hideFlags will be applied.

• Learn More: Check out the Unity HideFlags documentation.

4. Custom Shader Picking Logic

For a very specific and advanced method to prevent an object from being selected via clicking in the Scene view, you can modify its shader. Unity uses a special picking pass to quickly identify objects clicked in the editor.

By adding a specific pass with the tag "LightMode" = "Picking" in your custom shader and then ensuring this pass discards its result (rather than returning the object's _SelectionID), you can effectively make the object unresponsive to click-based selection in the Scene view. This method directly interferes with how Unity's editor picks objects on screen for fast selection.

• Conceptual Shader Modification (ShaderLab):

  Shader "Custom/UnselectableShader"
  {
      Properties
      {
          _Color ("Color", Color) = (1,1,1,1)
      }
      SubShader
      {
          Tags { "RenderType"="Opaque" }
          LOD 100
  
          // Standard rendering pass
          Pass
          {
              CGPROGRAM
              #pragma vertex vert
              #pragma fragment frag
              // ... (standard shader code) ...
              ENDCG
          }
  
          // Custom picking pass to prevent selection
          Pass
          {
              Tags { "LightMode" = "Picking" }
  
              CGPROGRAM
              #pragma vertex vert_picking
              #pragma fragment frag_picking
  
              // Minimal vertex shader for picking
              struct appdata_picking
              {
                  float4 vertex : POSITION;
              };
  
              struct v2f_picking
              {
                  float4 pos : SV_POSITION;
              };
  
              v2f_picking vert_picking (appdata_picking v)
              {
                  v2f_picking o;
                  o.pos = UnityObjectToClipPos(v.vertex);
                  return o;
              }
  
              // Fragment shader for picking - DISCARD!
              // Instead of returning a selection ID, we discard to make it unpickable.
              fixed4 frag_picking (v2f_picking i) : SV_Target
              {
                  // Discard the fragment to prevent the object from being picked by clicks
                  discard; 
                  return fixed4(0,0,0,0); // Should not be reached, but good practice.
              }
              ENDCG
          }
      }
  }

• Considerations: This is a highly advanced technique, generally only used when you need to prevent editor selection for custom rendering effects or complex editor tools. It requires knowledge of ShaderLab and Unity's internal rendering passes.

Summary of Methods

Method	Primary Use Case	Impact on Selectability	Ease of Use	Control Level
Locking a GameObject	Preventing accidental edits in Scene/Inspector	Cannot select via click in Scene; editable via Hierarchy selection	Easy	High
Layers and Scene View Visibility	Grouping objects, managing scene complexity	Hidden objects on a toggled-off layer are unselectable in Scene view	Medium	High
HideFlags (Scripting)	Programmatic editor control, custom tools	Can hide from Hierarchy/Inspector, make uneditable, or completely omit	Advanced	Very High
Custom Shader Picking Logic	Preventing click selection for specific visuals	Prevents selection via click in Scene view by modifying shader	Advanced	Very High

By understanding and utilizing these various methods, you can effectively control how objects are managed and interacted with within the Unity editor, enhancing your workflow and preventing unintended modifications.