CAP 151 - Introduction to Computer Animation

Lesson 6 - Parenting and Nesting


This lesson demonstrates using layers in groups, and organizing comps in parent/child relationships. Objectives important to this lesson:

  1. Grouping layers
  2. Nesting comps

The lesson begins with some definitions.

  • parenting - when one or more child layers are attached to a parent layer, we are parenting the child
  • nesting - when we add a comp to another comp (as though it were a layer), we are nesting the first comp inside the second one
  • precomp - a comp that has been nested inside another comp
  • master comp, main comp - a comp that has one or more othe comps nested inside it
  • precomposing - if you decide that some layers in a comp should have been placed in their own comp and that comp nested in the current one, you use precomposing to push those layers into that new comp, which is then nested in the current one
  • expressions - bits of Javascript code that connect one parameter to another
Tutorial Notes and Questions

Work through the exercises and turn in your answers to all questions below as part of the homework for this assignment.

Tutorial 1 (Parenting):

  1. Open the project and comp file indicated on page 136. Preview the animation to see what it already does. This step lays out some objectives: we want the rotating globe layer grouped with the circular text layer so they scale together. We want the text to rotate as well (orbiting the planet). We want to fade them as a group as well.
  2. This step shows the difficulty you would encounter trying to animate the two layers in the same way at the same time. If you skip it, reveal Scale, Rotation, and Opacity for both layers before continuing.
  3. Add the Parenting column to the Timeline panel as instructed. This step also gives us a rule for setting a parent/child relationship: if you want one layer to do something that should not be passed to the other, the first layer should be the child. (Children can inherit scale, position, and rotation from parents; parents will not inherit from children.) In this case, we will animate the text layer in a way that we don't want the planet layer to inherit. The text layer should be the child.
  4. The text shows us two ways to parent a layer. Both require the Parent column to be in the Timeline panel.
    Question 1: Describe the two methods briefly. Include the ridiculous name of the spiral icon referenced on page 136.
  5. If you have parented the text layer successfully, you can scale the parent layer and see both layers scale together. Do this. Set the scale values and keyframes as instructed for time 00:00 and 2:00.
  6. Confirm that rotating the text layer (child) does not affect the planet layer (parent).
    Set keyframes for the text layer as instructed. Preview again.
  7. Select the planet layer (parent), and change its Opacity as instructed. Note that this change is not inherited by the child. As stated above, the text tells us us that a child can inherit scale, position, and rotation, but anything else has to be set for children individually.

Tutorial 2 (Parenting With Nulls) presents the idea of parenting several layers to a layer made just to hold the others. Be aware of the concept, but don't do the tutorial unless you have time.

Tutorial 3 (Nesting a Group of Layers):

This tutorial starts on page 140. It introduces the idea of using a comp as a layer in another comp.

  1. Carry out the steps as indicated in the book. Make notes about the procedure.
  2. In the last step, make a title that is different from the authors' title.
  3. Question 2: Show me the comp for credit for the exercise, and turn in two questions (and correct answers) about the tutorial.

Tutorial 5 (Precomposing a Group):

This tutorial starts on page 148. It shows you how to make a precomp from layers that are already in a comp, replacing those layers with the new precomp.

  1. Carry out the steps as indicated in the book. Make notes about the procedure.
  2. Question 3: Show me the comp for credit for the exercise, and turn in two questions (and correct answers) about the tutorial.