#Free Ipas' from Sisyphus
13 messages in this thread
Eric and Audrey,
You two are amazing, thanx for a couple of very usefull routines. I'm sure I
speak for a majority of the participants here. It's a shame that more SXP's
were not written. It was an area which got panned for the most part with the
exception of the Yost Group, Sun Dog, and now yourselves.
Lee
Thanks Lee,
There's a reason why freeware SXPs aren't very common – except for some of the
swirly colors Pointer has done – and that's that very few people know how to
handle the bump mapping portion. The math involves some differential calculus.
Autodesk is so busy with MAX they really didn't have the time to show us how it
worked, and the only example supplied with the SDK that does bump-mapping –
DENTS – uses a 3D look-up matrix with weighted interpolation and fractalization
around each evaulation point…
So, anyway, we got past that and figured out how it had to work in general. If
you have access (or your nearby buddies at VI) to the MMDeveloper library,
you'll find a file there that goes through the nasty details.
Eric
What MMDeveloper library are you refering to?
Hi Lee,
<< MM Dev library.. >>
Requires Adesk MM Dev status.
jonas[adesk]
OH, SURE!,
You mean that I've got the IPAS Developers Toolkit and the Files Toolkit and
there's still somthing I am missing?
Sure Lee,
<< ..You mean that I've got the IPAS Developers Toolkit and the Files Toolkit
and there's still somthing I am missing? .. >>
Once part of the Adesk Registered MM Developer program, there are more
resources available to make you productive and profitable. If interested, you
should start a dialog with Phillip Miller , the MM Registered Developer Program
Manager.
jonas[adesk]
>>The technical discussion assumes an elementary understanding of first year
>>differential calculus, specifically the definition and meaning of partial
derivatives >>of functions in multiple independent variables.
Hi, Eric&Audrey!
We were busy tackling consequently PXPs, then AXPs and now IXPs with
BXPs (I mean, Fractal Flow and 2D Refraction do some ABSOLUTELY
IMPOSSIBLE stuff within available functionality of all thes XPs).
So, you are absolutely right, our next step would be making some
Wonders with SXPs.
Thanks for the info, I will read file with your discussion right away.
And, Yes, I do have "elementary understanding… et cetera" <g>.
It is (kind of) my profession…
Alex, Video International
I really like your SXP's nice effect.
Mike White [SDP]
>>I really like your SXP's nice effect.
Thanks, Mike!
With Proud,
Alex, Video International
P.S. But we don't have any SXPs (yet), what are you refering to?
<<<,P.S. But we don't have any SXPs (yet), what are you refering to?>>>
I've been really busy. I'll have them to you tonight.
Mike
Hi Aleksey,
Thanks for the thanks. We knew YOU would be able to handle the math, fer
cryin' out loud. I mean, you probably had calc in grade school, right? 😉
OK, OK, so maybe middle school….
-Eric
Hi, Eric&Audrey!
Thanks for the "SXP ineerworkings" file.
But let me point out to some "weak" points you've made:
1. You are not 100% correct stating that (F(x+dx,y,z)-F(x,y,z))/dx is
an estimate of partial derivative only at (x+dx/2,y,z).
It IS a valid estimate of dF/dx at (x,y,z) and for that matter at any point
from
(x,y,z) to (x+dx,y,z).
2. Second and MORE IMPORTANT: you are critisizing YG for
using (F(x+dx) – F(x))/dx instead of F(x+dx/2, x-dx/2).
Yes, it would be better estimate of partial derivative, but you
keep forgetting what it is used for.
YG restores implicit surface by Euler method: they need all partial derivatives
AND some STARTING point. Then they have to move from this point only
in one direction: what I mean is: x-dx/2 is UNAVAILABLE at the starting
point!
And one more note: there is a notion of false precision: you may evaluate
partial derivative better, but what the benefit if after that you will
numerically
integrate using trapezoids method – you will lose all gained precision right
away.
>>I mean, you probably had calc in grade school, right? 😉
>>OK, OK, so maybe middle school….
I had calc in the top mathematical boarding school = appr. 8th grade
(because I jumped through couple of school years, it is even 6th grade, not
8th).
But I still like it. 🙂
Alex, Video International
Hi Again,
Of course all your points are valid. I was imprecise in my use of the terms
'approximation' and 'valid at'. Thanks. We expected that you would be
stronger in mathematics than those of us who are 'home grown', and it's been a
LONG time since I actually had to use any of this stuff. That's what computers
are for ;-).
I didn't realize how strong, but I should have guessed. I have a friend in
Seattle who was educated at a Russian tool&die school, and he's the best gear
designer I've ever met.
Criticised YG? Me? Hmmmm… something I said must not have come across
precisely. I tried to make the point clearly that any approximation in Studio
that works is perfectly valid and useful – which is even more important here.
Thanks for the review 😉
Eric