Re: RE: Space Wars

This is probably a stupid question, but if MAME is having trouble with the
calculations now just how is adding yet another emulated device going to speed
things up? If anything I would think it would slow it further.

jeff hendrix wrote:

> 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
>
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--
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