RE: RE: Space Wars

I'm still working on it, I'm just taking a slight break right now.
I reduced the complexity for the polygons used in the ship to ship collision
detection routine, but it still slows down just enough to make in annoying.

Clay and I have been discussing the possibility to adding a math coprocessor
to the multigame kit. This would allow space wars, and any other game
anybody wants to write, to do as much math as they want without suffering
any speed loss. It would also mean that we would have to patch MAME to
properly emulate the new hardware.

-jeff

-----Original Message-----
From: Brian Deuel [mailto:bdeuel@pathwaynet.com]
Sent: Tuesday, February 01, 2000 8:28 PM
To: Vectorlist@Synthcom.Com
Subject: VECTOR: RE: Space Wars

Anyone know what ever became of this project? Jeff?

-----Original Message-----
From: owner-vectorlist@lists.cc.utexas.edu
[mailto:owner-vectorlist@lists.cc.utexas.edu]On Behalf Of jeff hendrix
Sent: Thursday, November 25, 1999 1:20 PM
To: vectorlist@lists.cc.utexas.edu
Subject: Space Wars

        My progress on space wars has come a long way, in other words, it's
getting close to being finished.

        I've run into a small snag. I was working on the ship to ship
collision routine and when I got it close to being finished I tested it out
and it slows MAME down to a crawl when it gets called. I'm checking every
segment against every segment in the opposite ship. I'm checking 11 on ship
1 and 9 on ship 2 for a total of 99 checks.

I'm implementing the following formula for each segment check (re-written in
assembly, of course, for a total of about 300 lines of code)

x1,y1 - shot initial position
x2,y2 - shot new position
x3,y3 - last point from ship used to check collision
x4,y4 - new point from ship used to check collision
a1=y2-y1
b1=x1-x2
c1=x2*y1-x1*y2
r1=a1*x3+b1*y3+c1
r2=a1*x4+b1*y4+c1
if r1 & r2 !=0 & have same sign, they don't intersect
a2=y4-y3
b2=x3-x4
c2=x4*y3-x3*y4
r1=a2*x1+b2*y1+c2
r2=a2*x2+b2*y2+c2
if r1 & r2 have same sign, they don't intersect

This works find for shot collision detection (I'm using the old shot
position and the new shot position for the line endpoints), but it's way too
slow for ship to ship.
What I'm wondering is, does anybody have a simpler way to check for the
intersection of 2 lines?

-jeff

---------------------------------------------------------------------------
** To UNSUBSCRIBE from vectorlist, send a message with "UNSUBSCRIBE" in the
** message body to vectorlist-request@synthcom.com. Please direct other
** questions, comments, or problems to neil@synthcom.com.
---------------------------------------------------------------------------
** To UNSUBSCRIBE from vectorlist, send a message with "UNSUBSCRIBE" in the
** message body to vectorlist-request@synthcom.com. Please direct other
** questions, comments, or problems to neil@synthcom.com.
Received on Wed Feb 2 11:12:11 2000