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To: "MicroWorlds Forum" <mwforum@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>, swanson6748g@xxxxxxxxxxxxxx
Subject: Re: MIA, Ask an Expert: Pong/Follow
From: "Daniel Ajoy" <da.ajoy@xxxxxxxxx>
Date: Mon, 20 Sep 2010 11:33:35 -0500

On Mon, 20 Sep 2010 09:48:33 -0500, <askanexpert@xxxxxxxxxxxxxxxxxxxxxxxxxxxx> 
wrote:

> from: <swanson6748g@xxxxxxxxxxxxxx>
> date: Mon Sep 20 08:48:32 2010
> platform: PC
> version: MicroWorlds Ex
> 
> I am currently in the process of creating a Pong-like game, with a 
> computer-controlled paddle that follows the ball with not-exact accuracy. For 
> example, if the ball moves up 4, the paddle only moves up 3, instead of 
> insantly teleporting to the position. However, it seems the if function (might 
> not be considered a function, I am too used to using lua) does not like the 
> turtle's ycor as a value to work off of.
> 
> Script in question:
> 
> to follow
> wait 0.1
> if t2's last ycor < last ycor [sety ycor + 1]
> if t3's "ycor > ycor = true [sety ycor + 1]
> end


It is more a problem of operation precedence. Your "if" command is being 
parsed this way:

(if (t2's (last (ycor < (last ycor)))) [sety ycor + 1])

This part:

last ycor < last ycor

should at least be:

(last ycor) < last ycor


Notice that "ycor" is a number and a word:

show ycor
59

So "last ycor" means: the last digit or character in the ycor number:

show ycor
59

show last ycor
9

Daniel
OpenWorld Learning





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