alice-teacher s Digest, Vol 38, Issue 6 - Edward Bujak comment

Mon Sep 9 07:34:58 EDT 2013

>> try to not code with numbers

Point well taken.  
If I had submitted something like that to a code review I would have been shot down immediately for using "magic numbers"

In my defense, The example I provided was from the materials supplied by the publisher of the book.  It took me a while studying the code to figure out what the 10.5 meters ment.

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From: alice-teachers-bounces+robert.durtschi=gcsu.edu at lists.andrew.cmu.edu [alice-teachers-bounces+robert.durtschi=gcsu.edu at lists.andrew.cmu.edu] on behalf of alice-teachers-request at lists.andrew.cmu.edu [alice-teachers-request at lists.andrew.cmu.edu]
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Subject: alice-teachers Digest, Vol 38, Issue 6

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Today's Topics:

   1.  Subject: Re:  questions RE: Angela Brown (Distler, Chari)
   2. Re:  collsion detection (s Digest, Vol 38, Issue 2) (Edward Bujak)

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Message: 1
Date: Sat, 7 Sep 2013 22:38:17 -0400
From: "Distler, Chari" <DistlerC at NBPS.ORG>
Subject: alice-teacher Subject: Re:  questions RE: Angela Brown
To: "alice-teachers at lists.andrew.cmu.edu"
        <alice-teachers at lists.andrew.cmu.edu>
Message-ID: <CE515B59.7E4E%DistlerC at nbps.org>
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Hi all,
I created a website for my students to follow my 12 week Alice course. Most of the material is from Adventures in Alice. I put the information in a format that was easy for my students to follow. Hope this helps.
https://sites.google.com/site/alicewithmsdistler/
Regards,
Chari Distler
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Message: 2
Date: Sat, 7 Sep 2013 21:53:04 -0400
From: Edward Bujak <edward_bujak at hotmail.com>
Subject: Re: alice-teacher collsion detection (s Digest, Vol 38, Issue
        2)
To: "alice-teachers at lists.andrew.cmu.edu"
        <alice-teachers at lists.andrew.cmu.edu>
Message-ID: <BLU175-W4598B633D6785768E915F4E63E0 at phx.gbl>
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Sorry about the previous mis-send with incomplete response.
Thanks you for the great example.As a software engineer and teacher, try to not code with numbers.  Get away from using hard coded numbers interspersed in code as fast as you can.  It is not good practice in the real world to have numbers within the code.  Documentation is not an excuse for not writing robust code.
For example if the penguin changed size the 1.1 meters would need to be adjusted.If the holes sizes were different then the 1.1 meters would surely be incorrect some of the time.If the snowbank donut object changed size then the 10.5 meters would need adjustment.
Please use the objects size properties of width, height, depth
The penguin cannot fall into a hole smaller than itselfif (penguin.width > hole.width)   cannot fall into this hole
For example a penguin being on the perimeter of a particular hole would beif (penguin.distance to hole) <= (hole.width + peguin.width)
For example a penguin being completely within a particular hole would beif (penguin.distance to hole) <= (hole.width -  penguin.width)

The 10.5 meters is probably the snowbank width, so use it. instead of hard coded numbers.if (penguin is at least snowbank.width away from snowbank)
Also using an objects many attributes helps teach better object-oriented coding practices.With Alice objects interacting in a 3-D world it also helps think more geometrically.
Of course the initial few weeks before the students realize that these are objects that have methods, functions, and properties using hard coded numbers are acceptable.
From: robert.durtschi at gcsu.edu
To: alice-teachers at lists.andrew.cmu.edu
Date: Sat, 7 Sep 2013 00:51:15 +0000
Subject: Re: alice-teacher collsion detection (s Digest, Vol 38, Issue 2)

The book "An Introduction to Programming Using Alice 2.2 Second Edition" by Charles W. Herbert has a rather nice collision detection method in Chapter 10: "TUTORIAL 10B?DON'T SPLASH
 THE PENGUIN!"

 I'll see if I can paste the relevent code here:

 This is a screenshot of what the playing field looks like. The goal is to manuever the penquin past the holes to the flag.  The collison dectection code checks if the penguin is within 1.1 meter of the center of each hole in the list; within 1/2 meter of the flag; or if trying to go through the snowbank surrounding the arena.

It rather cleverly defines the snowBank as a donut with the center in the center of the playing field.  so the check is to see if the penguin is 10.5 meters from the
center of the snowBank boundry

We found that if one didn't use a "Do together" it was possible for the penguin to beat its way through the snowbank and disappear over the horizon.

the check is invoked by a runtime event:

While the world is running

Begin:

<None>

During:

World.checkPenguinLocation

End:

<None>

The first check below: For all
hole1.holes , every item_from_holes
together" runs through the list of holes.  If the penguin is less than 1.1 meter from the center of any of the holes it pops up a "splash" billboard that covers the screen.

The second check
If (
penguin is at least
10.5 meters away from
snowBank ) checks if the penguin is too far from the center of the snowbank donut (center of the playing field) and moves it back towards the center.

The third checks

If ( (
penguin distance to
flagpole ) < 0.5 )
when the penguin is close enough to the goal.  It then invokes another method to indicate "Victory"

World.checkPenguinLocation
 ( )

No variables

Do together

For all
hole1.holes , every item_from_holes
together

If
 ( ( penguin distance to
item_from_holes ) < 1.1 )

penguin
move down 5
meters
duration = 0.25 seconds

splash
set opacity to 1 (100%)

Else

Do Nothing

If
 ( penguin is at least
10.5 meters away from
snowBank )

penguin
move amount = 1 meter toward
target = snowBank
duration = 0 seconds style = abruptly

Else

Do Nothing

If
 ( ( penguin distance to
flagpole ) < 0.5 )

World.reachedFlagpole

Else

Do Nothing

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From: alice-teachers-bounces+robert.durtschi=gcsu.edu at lists.andrew.cmu.edu [alice-teachers-bounces+robert.durtschi=gcsu.edu at lists.andrew.cmu.edu] on behalf of alice-teachers-request at lists.andrew.cmu.edu [alice-teachers-request at lists.andrew.cmu.edu]

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 Subject: alice-teachers Digest, Vol 38, Issue 2

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Today's Topics:

   1.  Collision and walking speed questions (Lori Fuller)

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Message: 1

Date: Wed, 04 Sep 2013 13:46:25 -0400

From: "Lori Fuller" <lori.fuller at browardschools.com>
 Subject: alice-teacher Collision and walking speed questions

To: alice-teachers at lists.andrew.cmu.edu

Message-ID:

        <fc.0119ec0746d675b63b9aca00e8ed6537.46d6890f at browardschools.com>

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I have an advanced student among all of my beginners... and he is working

on a maze game.

2 questions:

1.   In Alice 2.3, is it possible to set up a collision indication method?

If so, where do I find information on this?

2.  Is there a way to slow down the person object walking while using the

arrow keys as controllers?

thanks,

Lori Fuller, M.Ed.

Monarch High School

Career Technology Department Head

Technology Coordinator
 Asst. Athletic Director

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