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Chapter 1 3D Compositing 35
Root-Level Behavior
At the root level of the project, 2D groups behave differently than when they are
nested inside 3D groups. (For more information about root-level groups, see “Relative
Coordinates” on page 12.) 2D groups at the root level are locked to the camera, even if
the camera is animated. 2D groups at the top of the Layers list are always rendered in
the foreground, and 2D groups at the bottom of the Layers list are always rendered in
the background. Adjacent root-level 3D groups can intersect based on depth order.
In the example above, the two gray balls in the 2D Foreground layer are always
composited on top of the rest of the scene. The 2D Background layer is always
composited beneath the rest of the scene. Group A and Group B intersect because they
are 3D groups, but neither of them can intersect with either of the 2D root-level
groups.
2D and 3D Group Behavior
While 2D and 3D groups share a lot of common properties, there are distinct
differences in how they and their children behave and interact with other objects in a
project. 2D and 3D groups can be parents or children of each other; there are no
restrictions on mixing group types.
The Group Tab in the Inspector
In the Inspector, the Group tab appears when a group is the selected object. The Group
tab contains the Type parameter, which allows you to toggle a group between 2D and
3D mode. A 2D group has different available parameters than a 3D group.
When the Type parameter is set to 3D, the Flatten and Layer Order parameters become
available. When the Flatten checkbox is selected, all of the elements in the 3D group
are flattened like a “card” or “billboard.” When the Layer Order checkbox is turned on,
the group’s children are sorted by their order in the Layers list rather than depth order
(position along the Z axis). For more information, see “Layer Order and Depth Order” on
page 13.
Layers list Result in Canvas