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EnigmA AMIGA RUN 29 (1998)(G.R. Edizioni)(IT)[!][issue 1998-07 & 08].iso
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Deaceleration
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1998-02-17
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Date: Mon, 22 Sep 1997 16:53:27 -0600
From: Jim Belcher <jbb@koyote.com>
Subject: Re: [IML] QUEST: Deceleration on path
On 22-Sep-97, Tim Clarke wrote:
>Can anyone enlighten me on how to get a object following a path to decelerate
>for the last 30 frames. I can't seem to figure this sucker out. I've plugged
>values in for ending speed units/frame but I'm not seeing any difference.
>I have a path length of 55701 units that my object travels in 150 frames and
>I'm trying to slow it down at the end of the path.
>Any ideas?
>Thanks
>Tim Clarke
>(another Canadian IMLer from London, Ontario Canada)
I did the reverse of this for an aircraft accelerating on a runway. I figured
out the initial velocity and the terminal velocity. Using the expected rate
of acceleration, I moved the aircraft an appropriate distance each ten frames,
and set that value for that frame. Imagine then interpolated the in-between
values.
When I ran the animation, it was not at all evident what I had done. You
might
try the same trick, but in reverse.
----------------------------------
Date: Wed, 24 Sep 1997 22:24:29 +0400
From: Charles Blaquière <blaq@INTERLOG.COM>
Tim,
with these numbers, the object travels at an average speed of 371.34
units/frame. To get deceleration, you'll need to enter a number less
than 371.34 in the "ending speed" field, then enter 30 in
(Ac)Deceleration Frames. Often, people enter zero as the ending speed,
to have the object come to a standstill at the end of the path.
I believe objects that follow paths essentially have three speeds: they
begin at the starting speed on the first frame of the "follow path" bar,
ac(de)celerate to a fixed "cruising speed", then de(ac)celerate to the
ending speed on the last frame. Given the initial and final speeds, and
the number of ac/deceleration frames, there is always a cruising speed
that will fulfill the requirements and make the object arrive at the end
of the path on the desired frame.