alice-teacher Turn to face method (Alice 2)

[EILEEN PELUSO]

Hi Kevin,
Every Alice object as well as every subpart has an orientation.  That is, each has its own notion of which direction is its forward/backward, up/down, and right/left.  Some of the objects subparts are not what one would think they would be.  (When my students ask why, I tell them that the various objects have been made over the years by many different people and hence the inconsistencies.)

To determine the orientation of an object or subpart (let's use the spiderRobot's head for example):

Add an axes to your world.  (It's in the Shapes Gallery.)
Click and drag the axes tile from the Object Tree (Upper left) onto the image and let go.
Select "set point of view to"
Then select the object/subpart (for us, spiderRobot->neck->head->entire head).

This will move the axes to the object or subpart and shows us that subpart's orientation.  In this case, "forward" for the spiderRobot's head is actually out the back of its head.

I've attached a handout that I give my students that includes this at the bottom, except that instead of selecting "set point of view to", I have them do a "move" - "orient to" (which combined is a "set point of view to") along with at "set vehicle to."  Once the vehicle is set, when the object moves during the animation, the axis goes with it.  The visual is very helpful for students!

(Credit goes to Don!  I learned this trick from him at a summer workshop.)
Best wishes,
Eileen

From: alice-teachers-bounces+pelusoem=lycoming.edu at lists.andrew.cmu.edu [mailto:alice-teachers-bounces+pelusoem=lycoming.edu at lists.andrew.cmu.edu] On Behalf Of Frederick, Kevin
Sent: Wednesday, September 05, 2012 3:34 PM
To: Alice educators
Subject: alice-teacher Turn to face method (Alice 2)

Hi everyone,

Why do the "turn to face" or "point to" methods, when applied to subparts, do the opposite of what one would expect for some characters?

For example, suppose you want a spiderRobot's head (only) to turn to face an alien. Using spiderRobot.neck.turnToFace or spiderRobot.head.turnToFace has the effect of causing the spider robot to turn the back of its head to the alien. Ditto for spiderRobot.body.turnToFace. A penguin's head, however, has the behavior you would expect: it ends up looking at the alien.

Thanks in advance for any help!
Kevin
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