Re: [stella] time to stick me with a fork?

Subject: Re: [stella] time to stick me with a fork?
From: KirkIsrael@xxxxxxxxxxxxx
Date: 14 Mar 2004 16:58:16 -0000
Eric --
good eyes, man! Thanks for the catch. I found a clean solution:

I realized I was completely ignoring the "fractional byte"
of the Player's Position after a collision w/ the floor.  
In pre-subpixel joustpong, it was just a matter of setting the 
player's Y-coordinate.  

The current version it wasn't as simple: (well, duh)
There's an "interesting" interaction with gravity, or something,
because when I just set the fractional byte of the position to zero, 
the player was absolutely glued to the floor!  I wasn't expecting that.
Setting the fractional byte to a nice big number, #%11000000,
say, seems to work well.  (I think what happens is I put the Player's
integer position exactly where it needs to be to look right, but if
the fractional byte is too low, the player gets pulled down a bit,
and thus 'embeds' in the floor.  Or something.)

There was another manisfestation of this bug that I didn't 
see 'til figuring out how to get the bug you caughtt to repeat:
sometimes a slow collision w/ the floor would cause a bounce,
sometimes not.  I guess a slow rebound has a lot in common with
an initial flap, so it would very pseudo-randomly based on whatever
the fractional byte happened to be set to.

So, no need for "MudPong", I have a fix that, given its simplicity,
I feel pretty confident in.  (At one point my bandaid was "if player
hit the button THIS FRAME, skip the collision-with-floor check"--
which cleaned up the bug Eric spotted, but left the other manisfestation
I described)

Thanks again!

> > >I finally have a "release candidate" for JoustPong!
> > >
> > >
> > 
> > It might be a bit late, but one bug and one suggestion:
> > 
> > When you're sitting on the bottom, sometimes flapping doesn't have any
> > effect.  The wing flaps, but the paddle doesn't move.  I couldn't figure
> > out any pattern as to when exactly it happened.  Flapping again always
> > gets the paddle moving, but it does throw off your timing pretty badly.
> I'll look into it. At first I thought I thought "feh, it's just intertia
> he's seeing, original Joust had a similar effect" but now I kind of 
> see what you mean. Interestingly, I think it's more likely to happen
> when you let the player sit for a while...almost as if I kept the downward
> speed due to gravity going when it was sitting there, but not quite 
> (it would take a lot more strokes to build up any velocity in that case)
> I'm almost tempted to leave it, and say that the bug is that the just-printed
> manual should say that if you stay at the bottom, you're likely to sink
> into the mud...because that's *exactly* what it plays like.  

  "Aww Kate, nothing's corny if it gets you some." --Drew Carey

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