I've been 'playing' with scripting, and having a lot of fun, and have 
run into some problems or 'features', or have tried to do things that 
I can't appear to do. I know it's all new, that I don't know it very 
well yet, and that 2.6 may have changed it all; I'm still on 2.5 
(with all updates applied). Anyhow, I hope no one minds of I mention 
a few things I've run into.


* Highlighting button.

I've built a highlighting button by taking a rectangle morph and 
adding scripts that change it's color. One triggered on mouseDown 
changes it's color to the highlight color, and the other, triggered 
on mouseUp, changes it back. Works fine. I added some text, imbedded 
it, and locked it down. The button still works fine.

I then add a script for it to do something useful; in this case to 
turn a Car. If the turn script triggers off of something besides 
mouseDown or mouseUp then the button still highlights. But if I 
trigger off of mouseDown then it turns the car but forgets how to 
highlight itself. If I change the trigger of the turn script to 
something else, the button still won't highlight even though the 
scripts appear to have but one mouseDown again.

To fix it I have to reselect mouseDown for the highlighting script.

So, two problems here:

    - There can be but one script on a morph for each mouse action.
    - The system forgets to reenable other scripts with the same mouse
      trigger when one changes.


* Duplicating the highlighting button

Using the halo's duplicate operation, I made a copy of the 
highlighting button (which contains a reference to a Car morph; 
pressing the button turns the car). I was going to change it to turn 
the car the other direction. Result:

    - The button is duplicated AND the car is duplicated.

There are two cars and I can run and turn each separately. I expected 
two buttons that turned the same car. The two car morphs have the 
same name, 'Car', but separate existence and separate viewers.

Is this the proper action?


* Dragging

I've tried to build a car with a steering wheel that I can drag 
around in a circle like one moves a real steering wheel. (The example 
discussed here in August was quite neat, but it requires that halo's 
be accessible, and in a packaged product they won't.)

    - There is no way to specify a mouseDrag operation.

I'd expect, I think, for it to trigger its script while dragging (say 
at each tick). The script could see the current position (and maybe a 
delta). For rotation (see below) it would see a change in orientation 
(and maybe a delta).


* Rotation

On several things I've wanted to try, I wanted a morph to have a 
center of rotation. On one, it would have to be external from the 
morph (as in a handle that rotates around a hidden shaft). It's true 
that one can rotate a morph, but only about its center.

    - There is no way to specify a center of rotation.


* Hitting the wall

There seems to be no way to make a script that runs when a moving 
object hits the wall, though something clearly happens from all the 
noise it makes!  :-)


I've had various other problems but I can't duplicate them. Twice 
there has been a recursion that ran the VM out of memory, and it 
seemed to have something to do with scripting.

Dave

_______________________________
David N. Smith
IBM T J Watson Research Center
Hawthorne, NY
_______________________________
Any opinions or recommendations
herein are those of the author
and not of his employer.