You can make a light affect only one object in Blender by using the light's "Include" or "Exclude" lists to specify which objects it should interact with.
In Blender, the feature that controls which objects a specific light source illuminates is often referred to as Light Linking. This allows for precise control over the lighting in your scene, enabling creative effects or optimization by preventing certain lights from affecting everything.
The core mechanism for controlling which objects receive light from a specific source involves setting up Light Receiver rules. As the reference describes:
- Light receiver objects can be set to be either included or excluded.
- The behavior is as follows:
- If only included objects are specified, the light only affects those objects.
- If only excluded objects are specified, the light affects all objects in the scene except those specified.
To make a light affect only one specific object, you would select that object to be included in the light's interaction settings, while ensuring no other objects are explicitly included.
Steps to Limit Light Influence
Here’s a general approach to applying light linking in Blender:
- Select the Light: In your 3D Viewport, select the light object you want to modify.
- Access Light Properties: Go to the Properties Editor and click on the Light tab (the green light bulb icon).
- Find Relations/Linking Settings: Look for a section related to "Shading," "Relations," or "Light Linking." (Note: The exact location and naming might vary slightly depending on the Blender version and render engine, but the concept of Include/Exclude lists for lights remains consistent).
- Configure Include/Exclude Lists:
- You will find panels or lists for Includes and Excludes.
- To make the light affect only one object, click the "+" button in the Includes list.
- Select the specific object from the dropdown menu or list that appears.
- Ensure the Excludes list is empty (unless you want to exclude specific objects from the general scene illumination if you were using the exclude method).
- Make sure no other objects are added to the Includes list.
By adding just one object to the Includes list, the light will bypass all other objects in the scene and illuminate only the chosen one.
Include vs. Exclude Behavior
Understanding the difference between the Include and Exclude lists is crucial:
| List Type | Objects Listed | Effect on Light | Best Use Case |
|---|---|---|---|
| Include | Object(s) listed | Light only affects these objects. | When you want a light for specific object(s). |
| Exclude | Object(s) listed | Light affects all other objects in the scene. | When you want a light for the majority of the scene, but not a few. |
The reference explicitly confirms that if only included objects are specified, the light only affects those objects. This is the direct method to achieve the goal of making a light affect just one object.
This technique is useful for various purposes, such as:
- Highlighting a specific model.
- Creating special effects like focused spotlights.
- Improving render performance by limiting the calculations for certain lights.
By leveraging the Include/Exclude lists in your light settings, you gain precise control over how your lights interact with the scene geometry.
