Path: chuka.playstation.co.uk!news
From: "Rad" <rad@cyberdude.com>
Newsgroups: scee.yaroze.programming.2d_graphics
Subject: Re: What do'you mean I have to brush up on me maths!
Date: Sat, 3 Jul 1999 13:01:40 +0100
Organization: PlayStation Net Yaroze (SCEE)
Lines: 33
Message-ID: <7lkucs$ko217@chuka.playstation.co.uk>
References: <7ko1jf$33u25@chuka.playstation.co.uk> <376fbd21.251404588@news.scea.sony.com>
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Scott Cartier wrote in message <376fbd21.251404588@news.scea.sony.com>...
>
>You know the enemy location and the player location so you can use
>those two pairs of X,Y coordinates to form a vector.  Convert the
>vector to a unit vector so the distance doesn't affect the speed of
>the bullet.  Then each frame you add this vector to the current bullet
>position to make it move.  Multiply each component of the unit vector
>by some value to make the bullet go faster/slower.
>
>Take note.  Unless your bullet is moving very quickly, you'll need to
>make sure you have enough precision in your X,Y to avoid cumulative
>rounding errors.
>
>For instance, if your bullet vector turns out to be dX=4.1 dY=3.9
>(43.6 degrees) then when you add this to your sprite location it will
>only add the decimal part dX=4 dY=3 (36.9 degrees).  A noticable
>difference.

Hi Scott,

Ok, could you explain this with some example code or formula.
I need to work out dx and dy when I know x1, y1, x2 and y2.

It doesn't have to be super accurate, as long as the bullet travels roughly
in the right direction.

Thanks,

Rad.
rad@cyberdude.com
http://www.netyaroze-europe.com/~radpsx