## Re: [stella] Ho ho ho #1 (Boing)

 Subject: Re: [stella] Ho ho ho #1 (Boing) From: "Clay Halliwell" Date: Sat, 1 Jan 2000 16:06:49 -0600
Why blow memory on a vertical position table when you can just do it right
with a physics-syle solution? You could add a second byte to the
y-coordinate for fractional accuracy, and then it's as simple as
(pseudo-code follows):

// Simple vertical bounce
// initialize
ypos = 0
yvec = 0
yaccel = 1
ybouncestrength = -100
yfloor = 200

// main loop
blitballatyposition(ypos)
yvec = yvec - yaccel
ypos = ypos + yvec
if ypos > yfloor then
ypos = yfloor
yvec = ybouncestrength
repeat

Hmmm... I think that's right. Note that the constants are all wild guesses.

--
Clay Halliwell           | ATARI XL/XE   DO + THE
clay.FAKEMEAT.h@xxxxxxx  | 8 - B I T S   --------
e.halliwell@xxxxxxxxx    | ///////////   M A T H
Keeper of the Atari Jaguar Cheats and Codes FAQ. Request your copy today!
Editor, Jaguar Explorer Online - More Jaguar News Than Should Be Allowed!
http://www.atarihq.com/jeo/      "Where do you want to play Atari today?"

-----Original Message-----
From: Rob <kudla@xxxxxxxxx>
To: stella@xxxxxxxxxxx <stella@xxxxxxxxxxx>
Date: Saturday, January 01, 2000 12:16 PM
Subject: Re: [stella] Ho ho ho #1 (Boing)

>At 01:11 PM 1/1/00 +0100, Piero Cavina wrote:
>>Another nice touch would be a shadow for the ball. It shouldn't be
>>difficult to add, as it would always stay below the ball at a fixed
>>vertical position.
>
>Yeah, I like that!  Can't remember whether the original Amiga version had
it.
>
>I still might make the ball bounce the same way as the Amiga version (like
>a ball bouncing with 100% elasticity), by using a table of vertical
>positions instead of the Pong-like movement scheme I've got in there now.
>The shadow thing would go great with that.
>
>Rob
>
>kudla@xxxxxxxxx ... http://kudla.org/raindog ... Rob
>
>
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