As an example, let’s assume a situation where you shine a “light” only on a “character” that you see somewhere, as shown in the first diagram.
There is a background wall around the character, and in addition to the main spotlight (shown on the right in the image below), you want to use a parallel light source called “red sunlight” (displayed in orange on the left in the image below) as a fill light.
First, set the[Render Engine]at the top of the[Render Properties]tab in the property editor to “Cycles”. Unfortunately, “EEVEE” render is not supported at this time.
Light linking settings
Now that we’re ready, let’s set up light linking.
- Select the light object (here “Sunlight”).
- Click the Object Properties tab in the property editor.
- Open[Shading]-[Light Linking].
After selecting the light object (①), click the[Object Properties]tab (②) in the property editor, and open[Shading](③) -[Light Linking](④).
- Click the[+ New]button to create light linking data.
- Drag and drop the “Character” object from the[Outliner]tree above here.
After clicking the[+ New]button (①), drag and drop the “Character” object from the[Outliner](②)
Click the soap bubble-like icon at the top right of the 3D viewport to preview it.
Click the soap bubble icon in the upper right corner of the 3D viewport and preview…
…It’s not red (the correct answer is that it should look like the top image).
This is because the “background object” blocks the “sunlight” light.
Should I move then? No, this sunlight is a parallel light source, so its position doesn’t matter (here it is placed on the other side of the wall for clarity).
Therefore, we also set up “shadow linking”.
Shadow linking settings
Shadow linking controls how the light casts shadows on the target object.
As mentioned above, if the light is blocked, it means that a shadow is formed, so we need to prevent this.
- Open[Shadow Linking]in the same way as Light Linking and click the[+ New]button.
- Next, drag and drop the “background object” (here “cube”) here.
- Click the check mark to turn it off.
Similarly, open[Shadow Linking]click the[+ New]button (①), drag and drop the “background object” (②), and then click the check mark on the right (③) to remove it.
The key is to turn off the last check mark. This means “not creating a shadow = ignoring it”.
If the light used for light linking is not blocked by other objects, you do not need to specify this.
This worked fine.
It is illuminated by red light from the other side of the wall. wonder!
In addition, Illumination (indirect illumination) occurs due to the reflection of light shining on the target with light linking. . At least for now, it seems that the laws of physics cannot be twisted, and the only way to prevent this is to output them separately and combine them later.
An example to make it easier to understand.Only the leftmost light and the monkey are light linked, but it is also reflected on the cube.
If you want to remove only one item from the collection
As mentioned briefly at the beginning, this feature also allows you to specify a “collection”. For example, if you put clothes or props that are different objects and a character in the same collection and specify them using this function, you don’t have to specify them for each object individually.
If you want to release some of the objects in the collection, “Specify the objects you want to release in the collection as well and set them to OFF” as shown in the image below.
Example of excluding only the “T-Shirt” object in the “Character” collection from light linking
On the other hand, if you want to illuminate only a part of the collection, you can similarly specify the collection and the object you want to illuminate, then turn the collection OFF and the object ON, but in that case, simply specify only the object you want to illuminate and turn it ON. It might not make much sense since it would be faster to do this.