Re: New Vector Games

Your last paragraph explains why I'm having so much trouble.
Atari uses only relative beam placement (except for the center command)
I've got a draw ship routine working that draws the shape point to point and
I have all the rotating stuff working (I pre-rotate the shapes for the first
90, then I flop points around the x and/or y axises to get a full 360).
I was thinking of breaking it down to individual segments and have a
displacement vector between segments, I would then use the linear scale
command to scale down the displacement when the ship is whole, and then
slowly scale it up during an explosion (this would mean that the scale
command would change 26 times during a ship draw : there are 13 segments on
the star trek ship)
So If I do it this way (which is the only way I can think of), It will take
me a little bit longer to figure it out. I guess I also need to figure out
how much Vector RAM this will eat up, If I run out, I will have to draw each
ship every other screen.

-jeff

jeffh@diac.com
Buy/Sell/Trade classic video arcade games.
www.diac.com/~jeffh/
-----Original Message-----
From: Paul Kahler <phkahler@Oakland.edu>
To: vectorlist@mcfeeley.cc.utexas.edu <vectorlist@mcfeeley.cc.utexas.edu>
Date: Tuesday, December 29, 1998 4:44 PM
Subject: Re: New Vector Games

>> Hey guys,
>> I've come a long way on space wars (but I still have a long way to
go)
>> and I've run into some snags.
>> How exact do you guys want to see the original reproduced?
>> The big stubbling block I'm running into is trying to make the explosions
>> look like the original.
>> In the original, the pieces maintain their same angle and size and always
>> come off the ship at an angle based on the direction the ship is facing
>> (really cool looking, looks like the ship is growing in size)
>
>That's not too hard (did it for a PC Asteroids game (rocks 486)). One way
>is to define a parameter E that indicates how "exploded" the ship is, then
>each vertex is offset by E times some vertex-specific vector to make it
>fly away. Then as you vary E from 0 to n, the ship just explodes. This
>requires that no vectors share a vertex, as is commonly done - well they
>can, but you need 2 verticies at the same point. Technically each piece
>of the ship would get it's own direction vector multiplied by E, but I
>gave each vertex a direction - if you're careful, you can make a piece
>appear to spin as it flys away by giving each end a different direction
>to go - too much difference and it looks unnatural because the size of the
>piece changes (which can be cool if it shrinks slightly).
> BTW, since you have enough CPU and vector drawing time to draw separate
>vectors during the explosion (i.e. no connecting the dots) you can just
>draw it that way ALL the time with E set to zero.
> Oops! On cinematronics hardware this is simpler because ALL vectors
>are drawn in absolute coordinates where Atari uses mostly relative
>beam displacement as I recall. It may be a little more tricky but not
>too much I hope.
> BTW2, Do the "exploding" stuff BEFORE you rotate and place the ship
>on the screen, that way the explosion happens in "ship coordinates".
>
>Have fun,
>--
> ___ __ _ _ _
>| \ / \ | | | || | phkahler@oakland.edu Engineer/Programmer
>| _/| || || |_| || |__ " What makes someone care so much?
>|_| |_||_| \___/ |____) for things another man can just ignore.
" -S.H.
>
>
Received on Tue Dec 29 18:11:25 1998