From: Unigni <unigni AT zaynar DOT demon DOT co DOT uk>
Newsgroups: comp.games.development.programming.algorithms,comp.os.msdos.djgpp
Subject: Re: Calculating direction to shoot in
Date: Sat, 1 May 1999 16:59:56 +0100
Organization: Zaynar Productions
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In article <372AFE6B DOT D048BBCE AT webmail DOT co DOT za>, Ebola
<ebola AT webmail DOT co DOT za> writes
>I am programming a 2d space game. The game is seen from aboce and the
>player can rotate his ship so that he can travel in any direction, not
>just up, down, left and right. The problem is: How do I calculate the
>direction/angle the computer controlled enemies have to shoot in to hit
>the player? For example: The player is at coordinates (101, 254) and the
>enemy is at (235, 456). How can I calculate the angle between them?

The code used in QBasic is:

 Angle = ATN((x2 - x1) / (y2 - y1))

where x1,y1 would be the co-ordinates of the enemy ship, and x2,y2 would
be the target. ATN returns the 'arc tangent' (the angle -- in QB it's in
radians; I'm not sure about other languages...)
-- 
Philip Taylor
philip @ zaynar . demon . co . uk
http://www.zaynar.demon.co.uk/atr - Programming robots!