[stella] Jumpman missile jive

[Ruffin Bailey <rufbo1@xxxxxxxxxxx>]

KirkIsrael@xxxxxxxxxxxxx wrote:
> > I always thought they just worked like this: if player's X or Y is equal to 
> > the bullet's X or Y, and a random value exceeds a certain amount, make a 
> > noise and accelerate towards the player.  Never really even seemed like AI to 
> > me, and I finished both Jumpman Jr. and Jumpman back in the day ;)
>
> Finished? Wow, those games were tough.
> I always jonesed for a construction set for that game, but really, that 
> would only be plausible for the screen layout, and what really interested
> me about the games was the variety of enemies that had different behavior.
>
> Anyway, re: the bullet behavior: it's been a while, but yeah. I thought 
> each bullet started as either a horizontal or vertical slow traveller,
> and then if it lined up with the player it would "fire" and go faster
> (then again, I forget whether or not if it would fire if the player 
> "crossed its path" (you step in front of it and it starts going faster)
> or if it could reverse itself as it fired if you "crossed its trail".
>
> Still, not really an AI issue

I finished Jumpman on at least the first two levels (as in "levels of 
levels"), maybe the third (?), and did "Randomizer" quite a bit.  Fun stuff.

I suppose it could be as easy as splitting up the bounds of the frame 
into sections, randomly introducing the missiles to the screen, and 
having a chance of a missile shooting based on the distance from the 
player.  Now that you mention it, that's probably exactly what they did. 
 Every so often, you had one shoot from way over on the other side of 
the screen, and I often wondered why.  "Boy, that was a wasted shot."

So random x, random y, random direction of travel, and a percentage that 
it's going to shoot based on a little trig.  For some reason I had this 
idea that it was going to be more complicated than that, but this little 
voice (a la Magnum, if I'm trying to sound "k3w1") kept telling me the 
shots were going to be much much easier than moving critters in Adept.

I believe the bit that was confusing me is that when the missile sped up 
they didn't always shoot exactly towards you.  Perhaps they only had a 
few angles of attack, and were just picking the angle that got them 
closest.  Of course my memory anthropomorphized the missile a bit more. 
 Sometimes they would trap you in between for a "darned if you do or 
don't".  But I guess I played enough that could all be chance.

Thanks, Rob and Kirk, for the cold water in the face.  :^D

Ruffin Bailey

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