CAP 203 - Computer Animation III

Chapter 11: Parameter Wiring


This lesson covers material from chapter 11 of the text. Objectives important to this lesson:

  1. Wiring
  2. Following
  3. Rotation

There are only three exercises in this lesson, so let's see where they can take us.

The first exercise explains that it is sometimes useful to create a tool to control the motion of an object in your scene. This could be good for an object whose motion is hard to manage by hand. It might also be good to have a way of controlling what percentage of a motion path has been completed in several given frames.

Wiring 101

The first lesson we will consider in the chapter is Wiring 101 on page 212.

  1. Open the start file for this lesson. You should see a bead and a loop. The loop will become an animation path for the bead as well as a scene object. Follow the instructions in the text to apply a Path Constraint to the bead. It does not matter what part of the loop you click, the bead should go into the position shown at the top of page 213.
  2. Move the time slider as instructed. The bead should move on the path. Note that the hole in the bead is not lined up with the loop yet. You will not be able to see the Follow command on the Motion panel until you scroll the panel up. It is on the Path Parameters rollout, under Path Options. Tweak the settings on the Motion, Follow command as instructed to make the bead align with the loop. (Hint: try all three axis settings to see which one is right.)
  3. Select the Create panel, the Helpers tab, and the Manipulators dropdown. Click the Slider button. (It is shown selected on page 212.) On the Parameters rollout (not the Name and Color rollout), name the slider control. Click in the Front viewport to create a slider control. Move it and tweak it as instructed in the text.
  4. The slider doesn't do anything yet. Right-click the slider and select Wire Parameters (wire means connect in this case). Examine the popup menus that are displayed in this step on page 212 to see what items to select. Follow the directions to connect the value of the slider object to the percentage of the path the bead has followed.
    By the way, you should pause here for a moment. Note that you could have connected the slider to any of the three classic transforms for the bead object.
  5. Not done yet. A dialog box should appear, as shown on page 213. This needs a little more explanation. Clicking the right arrow button will set the slider (on the left of the dialog box) to control the bead (on the right of the dialog box). Clicking the Connect button makes it work.
  6. Step 6 tells you to click the Select and Manipulate button on the toolbar. It looks like an old-fashioned lug wrench with four sockets. This button allows you to use the manipulator in the scene, as opposed to the Select and Move tool letting you relocate the manipulator in the scene.
  7. Turn on Auto Key, but don't forget to move the time slider before making a change that sets a key. Save your file. Render an animation of it, and show it to me.

Follow me

This exercise is on pages 214 and 215.

  1. In step 1, load the scene file, which has a loop and four beads in it. Note the description in the text: the first bead is wired already, and each of the beads is separated by a specific interval from the ones next to it.
  2. Step 2 will look familiar, but it is different as well. Compare it to step 4 in the exercise above. This time you are setting a property for two beads. Follow the instructions in the text.
  3. Set the dialog box settings as instructed in the text.
  4. Animate with the slider to test the work so far.
  5. Continue to set up the third and fourth beads.
  6. Save your file, and open the second file for this lesson. Note the pitfall described in the text and its remedy.
    If you allow the first bead to move to position 0 on an open path, the other beads will be forced to the opposite end of the path by bad math. Correct this problem by setting a minimum path value for the first bead that allows the other beads to be remain on a logical part of the path.
    This problem does not exist in the BeadsFollow.max file supplied with the text. To see the problem, you will have to select the Slider object, choose the modifiy panel, and change the value for Minimum to 0.
    Do this and then demonstrate the problem version of this file. Save this version of the file incrementally.
    Note: this is not a problem if the path is circular, or any other shape that is a closed loop. It is only a problem is the path is not a closed loop.
  7. Render animations of the beads moving across the circle in the first file, and each way (good and bad) in the second file, and show them to me.

Telling time

This exercise is on pages 216 and 217. Upon examination, it does not appear to be instructive.

Pick something new

  1. It is time to make something new that displays lessons from your text.
  2. Pick at least two exercises from any chapters in the text. Write a project plan to use them to make something of your own. Your plan must include:
    • a storyboard for an animation,
    • a description of what you will do,
    • and a timeline for completing the assignment. (It must be completed before the end of the term.)
  3. Turn in your plan next week for approval.