Occlusion Culling

The occluder is a box shape that culls objects' surfaces, bounds of which aren't visible behind it. This is the simplest type of occluders that should be used together with box-shaped objects that block off other objects. For example, you can add an occluder the shape of which coincides with the bounds of a building to avoid rendering of objects behind this building.

To create a box-shaped occluder, perform the following:

1. In the Menu Bar, choose Create -> Optimization -> Occluder and add the occluder as a child to the node that should occlude other objects.
2. In the Common section of the Node tab in the Parameters window, set the position of the occluder to the parent one.

   

3. In the World Occluder section of the Node tab, click Edit Size to enable the editing mode for the occluder. Resize the occluder by using the colored rectangles on the occluder box sides so that it coincides with the parent node size.
   Notice

   You can also use the Size parameter to set the size along the axes.

   

4. Specify the Distance between the camera and the occluder, at which the occluder doesn't occlude anything and, therefore, should be disabled to avoid negative impact on the performance.

   

To check how the occluder works, disable the parent node and then try to toggle the occluder on and off:

By default, the front faces of the occluder are used to cull objects. However, if the camera is inside the occluder (e.g. inside the building), occlusion culling won't be performed. To avoid such situation, enable the Back Face parameter in the World Occluder section of the Node tab.

The occluder mesh is based on an arbitrary mesh that culls objects' surfaces, bounds of which aren't visible behind it. The occluder mesh is used together with the geometry that cannot be approximated with a box.

To create a mesh-based occluder, perform the following:

1. Prepare a low-poly mesh to be used for the occluder.
   Notice

   It isn't recommended to use the same detailed mesh that is used for the node that should occlude other objects: the mesh for the occluder should be as simple as possible to avoid performance loss.

   

2. In the Menu Bar, choose Create -> Optimization -> Occluder Mesh and specify the prepared mesh.
   Notice

   You can load a new mesh for the occluder at any time.
3. Add the occluder as a child to the node that should occlude other objects.
4. In the Common section of the Node tab in the Parameters window, set the position of the occluder to the parent one.

   

5. Specify the Distance between the camera and the occluder, at which the occluder doesn't occlude anything and, therefore, should be disabled to avoid negative impact on the performance.