Path: chuka.playstation.co.uk!scea!peter_alau@playstation.sony.com
From: Elliott Lee <tenchi@jps.net>
Newsgroups: scea.yaroze.programming.2d_graphics
Subject: Re: Collision Detection
Date: Mon, 27 Jul 1998 13:52:33 -0700
Organization: Cisco Systems
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These are some theories that may just work:

Antony Arciuolo wrote:
> 
> What is the best method of collision detection for a Starcraft-ish game?
> 
> Two problems: One is that the square sprite is rotated, so how can the

Use a circle instead of a square. OK, when the sprite is "straight", it
will cover a little more area that you'd like to, but it should be OK
for most purposes.  I'd make the circle (or elipse, actually) just a
little smaller than the longest line from the dead center of the sprite
to one of the corners.

	[...]
> The other is that for some of this, the object is highly irregular, like a
> puddle or lake. It is a key component of the project that the puddle be
> this irregular, so redesigning the puddle so it is more square is an
> unfavored option.

Well, since this object is probably part of the playing field, why not
make the playfield into a grid and have the lake span multiple grid
cells.  You've seen games like Sim City, aye?  you can clearly see the
cells that have water and those that do not.  In Star Craft, the same
grid system appears to be employed, although with the funky rounded
graphics for edges of, say, higher terrains appear to be rounded even
though they are not.

> My real question is can I directly access the frame buffer (a short
> GetPixel(short X, short Y) function) and how can I use this to reference
> the palette of the puddle so I can use palette collision detection?
	[...]

Hehee...  I used to do that a long time ago.  It's OK but just wait
until you have objects that overlap that visual space.  Plus, you'll
have to make sure you make a background snapshot of the ground BEFORE
you slap graphics down on top, otherwise you'll end up getting all the
wrong colors.  ^_^  I think your best move is probably the grid system.

Mata ne,           ...                                          ...
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