Obliterate AIs: Parabolic Pain

qazz42 · Vampire Killer Joined: 07 Apr 2010 Posts: 4179

err, this is off topic and noobish, but

1. what type of math is that?
2. what grade do you learn that in? Shock

my brain hurts from looking at it.
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souvik1997 · Guru-in-Training Joined: 19 Apr 2010 Posts: 2870

It looks like vector math.
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KermMartian · Posted: 22 Feb 2011 10:00:56 pm Post subject:

It's one solution to the parabolic motion equations in 2D expressed as Cartesian coordinate pairs.
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elfprince13 · Posted: 22 Feb 2011 10:07:04 pm Post subject:

KermMartian · Posted: 22 Feb 2011 10:09:23 pm Post subject:

We have it, I just don't like using it for some reason. And yes, that multiplication is only for the latter term of S.
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Pseudoprogrammer · Awesomesauce Joined: 12 Dec 2006 Posts: 890

I got, probably through a different method:

x = x2 - x1
y = y1 - y2

V0 = sqrt(-(sqrt(((x/cos(t))^2)((sin(t)^2)+2gy))-xtan(t))/(2gy)))

Visualized: C and P the whole link; Kerm's BBcode fails.
http://www.wolframalpha.com/input/?i=sqrt(-(sqrt(((x/cos(t))^2)((sin(t)^2)%2B2ay))-xtan(t))/(2ay))

elfprince13 · Posted: 22 Feb 2011 11:09:45 pm Post subject:

Add it to the BBCode buttons list you silly thing! And I started to check it, but remembered I need to finish 2 papers tonight...
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KermMartian · Posted: 22 Feb 2011 11:19:45 pm Post subject:

Pseudo: don't forget that I'm working in z80 ASM. I have a sine and cosine lookup table of low-ish precision for theta=0 through theta=180, but square room, tangent, etc are expensive. Mine also has a sqrt, unfortunately, although I originally omitted it. I edited my post above accordingly. I'm not sure why you have so many square roots...
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Pseudoprogrammer · Awesomesauce Joined: 12 Dec 2006 Posts: 890

I used:
0 = -.5at^2 + VyT + (y2-y1)
and quad formula'd it to find the amount of time T it would be in the air which is
(V0sin(t) + sqrt((V0sin(t))^2 + 2a(y2-y1)))/a

then I find the amount of time T it would need to be in the air to travel the X distance (which is V0cos(t) )
so:

t=(x2-x1)/(V0cos(t))

set the two equations equal to each other and solve for V0.

KermMartian · Posted: 22 Feb 2011 11:28:06 pm Post subject:

That was my original approach as well, but I didn't like the square root that that required. Unfortunately, it then turned out I would need a square root anyway.
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Pseudoprogrammer · Awesomesauce Joined: 12 Dec 2006 Posts: 890

How did you arrive at your solution?

KermMartian · Posted: 23 Feb 2011 12:09:12 am Post subject:

elfprince13 · Posted: 23 Feb 2011 02:14:14 am Post subject:

Methinks we need "The (Other) Vector Thread" to stop diverting this one Razz

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Pseudoprogrammer · Awesomesauce Joined: 12 Dec 2006 Posts: 890

I solved the equations again using a different method and I got:

sqrt((y1 + tan(t)(x2-x1) + .5a((x2-x1)^2))/(y2cos(t)))

Not sure if they're equivalent.

KermMartian · Posted: 23 Feb 2011 11:46:10 am Post subject:

Doesn't seem to be equivalent. I don't think that that equation is correct; if y2 = 0, then you get division by zero, and not every equation with a final y-coordinate of zero is unsolvable...
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KermMartian · Posted: 24 Feb 2011 02:29:13 am Post subject:

Hmmm, here's the latest thing I came up with.

comicIDIOT · Posted: 24 Feb 2011 03:49:48 am Post subject:

I can't understand the fine specifics here, but I wouldn't call this AI until each tank can assess a situation.

Which tank poses a greater threat (closer tank first then most accurate tank targeting it as the game progresses)
Tank knows how far off it was from an enemy tank and adjusts next turn accordingly

This is likely for version two, if anything. From what I understood above the AI chooses a tank at random and random settings each turn.

The tanks are on a master graph. Tank A at -30pxls away from the origin, Tank B at +10. Then, each Tank is at the origin of it's own graph. When Tank B fires short of Tank A the value would be, say, 13. If it overshot the value would be -6.

If it was short, it'd either adjust the power up or the angle down. Even Power up*2 and angle up.

Only problem is that you'd have to store values for each tank. So you'd have n-1 lists of n elements denoting accuracy on individual tanks. (-1 for a human player). But, each tank would only have access to it's own list to prevent each tank from targeting the one tank until it's dead then moving on to the next most accurate.

I don't expect that last paragraph to make much sense to anyone else and it probably won't for me in a day. But, how exactly does the AI work in English?
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KermMartian · Posted: 24 Feb 2011 12:30:50 pm Post subject:

You vastly overestimate how easy manipulation of all this math is in z80 assembly. Smile

I'm already suffering enough with a targetting AI; I don't feel like complicating it any more at this point. You've presented a good system, though, and one that would make sense if in the future I have more patience. At this point I'm mostly interested in getting a decent AI working, publishing a beta, and starting Direct USB gCn. And yes, it's a real AI because it adjusts the angle and power properly to hit an enemy tank.

Edit: I remembered that my sin and cos are 100-scaled. Improved magnitude estimates.

KermMartian · Posted: 25 Feb 2011 02:12:04 pm Post subject:

*bump* I can has partial success burger? I suspect they're just using the wrong delta-Y now.

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