Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!utgpu!water!watmath!clyde!rutgers!ucla-cs!zen!ucbvax!hplabs!pyramid!prls!gardner
From: gardner@prls.UUCP
Newsgroups: comp.sys.mac
Subject: Physics and Computer Games
Message-ID: <6277@prls.UUCP>
Date: Fri, 18-Sep-87 13:35:24 EDT
Article-I.D.: prls.6277
Posted: Fri Sep 18 13:35:24 1987
Date-Received: Sun, 20-Sep-87 02:16:15 EDT
References: <1470@ingr.UUCP> <11540017@hpsmtc1.HP.COM> <6275@prls.UUCP>
Reply-To: gardner@prls.UUCP (Robert Gardner)
Organization: Philips Research Labs, Sunnyvale, California
Lines: 59

This may not be the right forum for this, but...

I'm concerned about the number of computer games/simulations lately
that incorporate incorrect physics. I'd like to see a "Stomp out
Bad Physics" movement to help programmers get it right.

As an example let me mention Dark Castle and StuntCopter. Now, I don't
do any of this to embarrass the programmer/developer/publisher of
these (or any) packages. These both happen to be excellent programs
that are a lot of fun. But I worry about what they are teaching the
people (children, esp.) who use them about physics. The understanding
many people have of the physical world is already pretty bad. And
the fact that these programs show these problems is further evidence
that even intelligent, capable people can have misconceptions about
the world. If this could be remedied I believe the technological 
achievements of the mankind could be even more remarkable...

So, now the examples:
Dark Castle: When swinging across the ropes (in the dungeon) the
way to successfully jump from rope to rope is to jump when you are
at the top of your swing. Jumping too soon or too late causes you
to miss the second rope. Now, admittedly, timing is a big issue in
doing this in real life, but the fact remains that at the top of
your swing you no longer have any forward momentum. If you let go
of the rope at the top of your swing you will therefore fall straight
down and not go forward at all. I had a hard time figuring out how
to jump the ropes successfully in Dark Castle because I kept feeling
like I should be trying to jump forward to catch the next rope so
I was always jumping too soon. (The animation clearly shows a jump
rather than a 'reach'.)

StuntCopter: This problem is much more bothersome. Here the goal is
to fly a helicopter over a moving cart, drop a man from the copter
and have him land in the cart. The problem is in the trajectory
of the man after he lets go of the helicopter. In the game he always
falls straight down from the helicopter regardless of the helicopter's
speed or motion. In real life (assuming no wind) the man's forward
velocity as he falls should be exactly the same as it was the moment
he let go of the helicopter. In other words, if the helicopter is
flying exactly over the cart, moving at the same speed as the cart,
then the man should land in the cart when he lets go, regardless
of the speed at which he falls. If there is a wind then the wind
velocity should be added to his initial velocity, so if the helicopter
is flying into the wind he doesn't go as far, if it's flying with
the wind then he goes farther. (Wind resistance is actually somewhat
more complicated than this, but this gives you the idea.)

Sorry to flood the nets with this gibberish, but I feel very strongly
about the issue and I think it's the programmers/developers/publishers
that need the message the most since they're the ones providing
the games/simulations. Actually it's kinda nice that the software
is good enough that things like this are noticeable! Keep up the
good work, but "Stomp out Bad Physics"!

Robert Gardner

P.S. If anyone knows of a (more) appropriate forum for this message
please cross-post it and/or let me know so I can see if it gets
any reaction. Thank you.