Subject: Re: moving balls on water
From: Ernie Wright <[email-masked]>
To: Multiple recipients of list <[email-masked]>
Date: Fri, 26 Apr 1996 22:29:20 -0700

[email-masked] wrote:

> AHA!  This is the crux:  The displacement vectors are CALCULATED using 
> the original points, but are APPLIED to the morphed points.

Yes.  It might help to forget for a minute that these are happening in
sequence.  Displacement and morphing are both linear translations, and
since vector addition is commutative, the order in which they're added
together doesn't matter.  What matters is how each vector is calculated.

Both the displacement and the morph are relative to the original, undis-
turbed points.

See?  They're independent, externally at least.  In other words, LW does
NOT

   1.  morph the displaced points, or
   2.  displace the morphed points.

What it does (or rather appears to do), is

   1.  find the amount to displace the original points
   2.  find the amount to morph the original points
   3.  add (1) and (2) together

- Ernie