Distance to

[gypsy fly]

In one of the Chapter 3 exercises, a dragon is supposed to fly aorund a blimp.

One of my students did a move forward distance from the dragon to the blimp. It went way past the blimp about twice as far. Doing a distance to from the blimp to the dragon ... works.


why?

[gypsy fly]

I can't replicate on my home computer. Maybe there some setting on the lab PCs that's affecting it. Wish I could find out what. The student showed me the problem on his workstation and I was able to replicate it on the instructor station.

[DrJim]

I can replicate the problem but can't explain it. Looks like a real bug with the blimp object.

In the attached, note that the blimp to .... and the .... to blimp distances do differ by a factor of approximately two. The chicken-dragon distance, however, is the same no matter which direction the test is made.

[gypsy fly]

Thanks for the confirmation!

Last Friday, for homework, several of the students did Chap 4: #7 "Magic Art". The magicians left hand is oriented differently from the right. So in order to move both hands to the magicians side, one hand had to be rolled while the other turned.

How does one access the original model to make the corrections? Must we always be at the mercy of the artists?

[gypsy fly]

I can replicate the problem but can't explain it. Looks like a real bug with the blimp object.

In the attached, note that the blimp to .... and the .... to blimp distances do differ by a factor of approximately two. The chicken-dragon distance, however, is the same no matter which direction the test is made.

I dropped an "orient to" in your test program prior to the debugs ... it worked after that. Interesting bug, isn't it?

What's more interesting is how my students reacted to the bug. Some picked up on my "Oh well, go figure!". Many got rattled and perturbed.

Since CTEC 120 is a Beginning Programming course, and a pre-req to everything, I feel teaching them attitude is as important as aptitude.

I ought to find another "blimp" and stick it in the next in-class project.

They'll live!

[DrJim]

How does one access the original model to make the corrections? Must we always be at the mercy of the artists?

For now, that seems to be the case. I don't know what the situation will be with Alice 3.0.

Your blimp experiment was interesting - as well as "instructive."