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Subject: MIA, Ask an Expert: gravity, asciis, ...
From: mwforum@xxxxxxxxxxxxxxxxxx (Mike Sandy)
Date: Thu, 7 Oct 2004 19:27:46 +0100

Daniel's program raised
the question, exactly when
is the test for touching? applied?

The test can be used in several
ways:
1. As a WHEN[touching? "bullet "target][..]
 process
  a. in SHOOT as in Daniel's program
  b. in startup, e.g.

to startup
  target, forever[fd .05 * targ_vel]
 t2, st 
 bullet, setpos t2's "pos st
 forever[if readchar  = "| |[shoot]]
 when[touching? "target "bullet]
   [announce[HIT!]
    bullet,  setpos t2's "pos ht
    ] 
end


 
2. For "bullet
 repeat 200
  [ifelse touching? "bullet "target
    [announce[HIT!]
       bullet,  setpos t2's "pos ht
    ]
   [fd 1]
  ]
 or similarly for  "target.

After a bit of experimenting I found
the test is applied only after the
turtle stops moving(obvious for 2).

 The main difference between 1. and 2.
is that a hit was possible for 1. only with 
a lower bullet speeds  
With 2., hits were possible with much faster
speeds e.g. fd 10.
Anyone suggest why?

Perhaps someone with quicker responses than I have,
will find otherwise.

It does suggest that method 2. has the advantage.

Compare the number of hits you can make with the
program using WHEN(1) and then using IF(2). 
Select using slider "when/if", the text underneath
won't change until you press GO.



Mike


 
 

Attachment: shoot1.mw2
Description: Binary data


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