2D and 3D Group Intersection

The 3D group type adds a new level of flexibility to your projects, but also creates complex interactions between group types.

Groups can either be 2D or 3D, and it is possible to change a group’s type at any time.

To change a group’s 2D/3D type
  • In the Layers tab or Timeline, select the group you wish to change, then do one of the following:

    • Choose Object > 3D Group (or press Control-D).

    • Click the 2D/3D icon in the Status column in the Layers tab.

      Figure. Layers list inset showing the 2D and 3D group icons.
    • Click the Type pop-up menu in the Group tab of the Inspector.

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.) 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 tab are always rendered in the foreground, and 2D groups at the bottom of the Layers tab are always rendered in the background. Adjacent root-level 3D groups can intersect based on depth order.

Figure. Layers tab and Canvas showing layer arrangement containing both 2D and 3D groups.

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 Interaction

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.

Important: Some operations, as well as the application of certain filters or a mask, cause a group to be rasterized. When a group is rasterized, it is converted into a bitmap image. Rasterization affects 2D and 3D groups in different ways. For more information, see Groups and Rasterization.

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, a pop-up menu that allows you to switch 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 selected, the group’s children are sorted by their order in the Layers tab rather than depth order (position along the Z axis). For more information, see Layer Order and Depth Order.

When the Type parameter is set to 2D, the Fixed Resolution parameters become available, allowing you to manually define the size of a group. By default, Fixed Resolution is disabled and the size of the group is determined by the layers within that group. For more information, see Fixing the Size of a Group.

Note: When selected, Fixed Resolution crops the group to the size specified in the Fixed Width and Fixed Height parameters, around the anchor point of the group.

2D Group Properties

A 2D group has the following properties:

  • Its children are composited in layer order.

  • Filters are applied to the group in local space; that is, “flat” to the image.

    Figure. Canvas window showing a Checkerboard in a 2D group with a Twirl filter applied.
  • The group is lit as a single object; its children are not lit individually.

    Note: 2D groups at the root level are not lit.

  • Because it is always flat, a 2D group has Crop, Drop Shadow, and Four Corner parameters.

  • It can have a fixed resolution.

3D Group Properties

A 3D group has the following properties:

  • Its children are composited in depth order (according to their position along the Z axis).

  • Filters are applied to the group in view space. In other words, the filter affects the group as if it was applied to the lens of the camera viewing the group.

    Figure. Canvas window showing a Checkerboard in a 3D group with a Twirl filter appled.
  • Its children are lit individually.

  • Only a 3D group with the Flatten parameter enabled has the Crop, Drop Shadow, and Four Corner parameters.

Working with Objects Inside 2D Groups and Flattened 3D Groups

You can use the Isolate command to align the active view with the axis of a 2D group or flattened 3D group. Doing so facilitates making adjustments to objects inside the group. For more information on the Isolate command, see Isolate.

Should you be unable to find an object in your project, you can locate it by resetting its Position parameter to 0, 0, 0. This centers the object in the flat group.

When moving an object along its Z axis inside a flat group—which includes 2D groups and flattened 3D groups—the object appears to grow larger or smaller rather than move closer to or further away from the camera.