RE: MIA, Ask an Expert: turtle as eraser

["Alain Tougas" <alain@xxxxxxx>]

Hi!

You cannot erase "parts" of other turtles. One (definitely not easy) option
consists of making each tetris piece using several turtles. One difficulty
is the "rotate" procedure, which is different for each piece.

The 2 by 2 square is easy to rotate. Nothing to do

to rotate2by2
end

The 1 by 4 bar could be:

to rotate1by4 :tname1 :tname2 :tname3 :tname4
ifelse vertical?
     [gohorizontal]
     [govertical]
end

Next proc moves the turtle1 20 steps to the left, turtle2 20 steps up,
turtle3 20 steps up and to the right, turtle 4 20 steps up ant 40 to the
right

to gohorizontal : tname1 :tname2 :tname3 :tname4
ask :tname1 [setx xcor - 20]
ask :tname2 [sety ycor - 20]
ask :tname3 [sety ycor - 20 setx xcor + 20]
ask :tname4 [sety ycor - 20 setx xcor + 40]
end

to govertical
...
...
end

Then, each time a piece moves down, you have to check if you have a full row
somewhere. For that, check how many turtles have a ycor of 0. If you have
10, kill that row. Then check how many have a ycor of 20. If you have 10
turtles there, etc.

I didn't test that. It's just a theory.

Good luck. Keep playing. Even if you don't make it to "full success", your
efforts will be worth... your efforts. That's always something.

Alain

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Subject: MIA, Ask an Expert: turtle as eraser

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from: Doug Alexander <dalexander@xxxxxxxxxxxxxxxxx>
date: Wed Oct 10 06:49:35 2007
platform: Mac OS10
version: MicroWorlds Ex

How do I make a turtle turn into an eraser to erase parts of the
existing turtles? I'm trying to enhance the FallIntoPlace example
on the MicroWorlds site, but I need a way to erase lines and "drop"
the remaining turtles one row down. Not sure this is possible - help?