Aminet 25/Aminet 25 (1998)(GTI - Schatztruhe)[!][Jun 1998].iso/Aminet/gfx/3d/IIB10.lha/IIB/Threads/Pushin_thrugh

Internet Message Format | 1998-03-02 | 9.9 KB

Date:         Tue, 23 Dec 1997 23:41:08 -0600
From: chris johnson <[e-mail]>
Subject:      [IML] quest:Pushin thru rubber

hi all,
Im working on a anime,where a hand comes pushing through a wall
of rubber or whatever,my problem is when you push through wall
the farther you push the larger the radius of distortoin or stretching
will be, using aplique I can make the hand push through the wall
and it looks good but it is a static stretch(meaning it doesnt
effect the rest of the plane.Im wanting to have the hand slide around
in the rubber .So is there a way to do this maybee like magnatisn
or whatever

thanks

BTW I have IFW.

----------------------------------

Date:         Wed, 24 Dec 1997 07:23:43 -0600
From: "Stephen G." <[e-mail]>

I don't think magnetism is the solution but why not just move your applique
map around the surface of the plane and save each keyframe as a state or
you could make an animated flic or AVI and use that as your applique map.

----------------------------------

Date:         Wed, 24 Dec 1997 11:42:53 -0600
From: chris johnson <[e-mail]>

thanks stephen
Ill give it a shot

----------------------------------

Date:         Wed, 24 Dec 1997 04:34:18 -0600
From: Mike Bayona <[e-mail]>

There are two ways at current I can think of that might do it.  The first
is by using the "Animated Applique" winbatch script, found at:
http://www.dorsai.org/~eno/progress.html


The second way will only work if you are subscribed to the CUP, and may not
work as well....  Make a deform tool with various states (so it deforms the
wall like the hand is moving the fingers or whatever) and then load it into
stage, have IT be morphing states as you move it around the wall.  But I
think for something as complex as a hand stretching a wall, you will need
to go with the first one....

----------------------------------

Date:         Fri, 2 Jan 1998 03:30:33 +0400
From: Charles Blaquiere <[e-mail]>

(Some of these instructions use Photoshop terminology. Users of other
software should be able to figure out what's going on. I'm also
supposing your hand is white on a black background.)

I see two stages to your animation: what happens before the hand has
pressed just far enough to show all the fingers, and what happens after
that.

STAGE 1: THE REVEAL

You should use Levels to create a series of brushmaps, progressively
revealing the hand, starting with the highest altitude areas. For
example, change Input to 192-255 (leave Gamma alone) and Output to 0-63;
this floods everything below 192 with black, and maintains the same
range in the output (64 levels, from 0 to 63) as in the source (64
levels, from 192 to 255). Save as Reveal-1.

Revert to the original, and use 128-255 as Input and 0-127 as Output.
Save as Reveal-2. Revert again, this time setting Input to 64-255 and
Output to 0-191. Save as Reveal-3. Copy original image as Reveal-4.

In Imagine, create a DEFAULT and START stage for your (heavily-divided)
plane. Apply Reveal-1 as an Applique and Create the REVEAL-1 state with
Shape turned on. Set To START, apply Reveal-2 and create the REVEAL-2
state. Do the same for REVEAL-3 and REVEAL-4.

If you animate this, it'll look more as if a hand was _progressively_
pushing through the rubber, than if you simply animated the Applique Y
size from the single hand image; in the latter case, it would look as if
the entire hand was stretching from a flat shape into its final, full
appearance. (Of course, my technique may have its drawbacks too, as the
each area is progressively revealed in turn; if it doesn;t look right,
you may need to create more brushmaps and Applique them to more states)

STAGE 2: THE PUSH

Once the hand appears fully formed, further pushing will (1) _move_ the
rubber where the hand is, in the direction of the push; and (2)
progressively _stretch_ the surrounding areas, further away from the
hand as it pushes forward. To do this, we'll create two more brushmaps.

From Reveal-4, which is the original brushmap, create a version where
the entire hand is white and the entire background is black. Save as
Push. You should also save the selection you used to fill the hand, for
later use.

Create a new image and fill it with black. Activate the saved selection
and fill it with white. Do a Gaussian Blur on the entire image with a
large radius, perhaps the width of one finger. You'll get a very blurry
image, with the blur extending quite a distance away from the hand.
Activate the hand selection again and fill with black. Deselect and
manipulate the levels so that the output uses all levels from 0 to 255.
Save the image as Stretch.

What you have done is add an area around the hand, similar in appearance
to an aura or glow, that will simulate the way the material is stretched
around the hand when pressed through the rubber sheet.

Go back to Imagine. Let's say you wish to create an additional state,
where the hand has pressed 50 units further into the sheet, than the
position in the REVEAL-4 state. We'll create the final state in two
steps: first, we'll move all the points inside the hand 50 units
further  away from the plane, then we'll create the stretch.

Load the rubber sheet and Set To REVEAL-4. Applique the Push image,
using a distance of 50 units. The hand will move forward by that amount
without stretching (since it's filled with a constant white in the Push
image), but the rest of the sheet will remain untouched, leaving a
precipice-like contour around the hand. (Imagine the rubber sheet as a
horizontal ground plane) This is most unnatural, but we're only halfway
through.

Next, Applique the Stretch image, again with a distance of 50. Since the
hand in the brushmap is totally black, the hand's points will not move
at all, nor will points far away from the hand. However, as we get
closer and closer to the hand, the points will move more and more;
points right at the edge of the hand will move 50 units, since their
brushmap pixels are white. This makes the rubber sheet's points right
outside the hand, move to meet up with their neighbors, right inside the
hand, for a seamless fit; at least, that's what BVRE (Blaq's Virtual
Rendering Engine) tells me.

You can now immortalize your creation in a final state, perhaps called
FINISH. When you animate the object from START to REVEAL-1, REVEAL-2,
REVEAL-3, REVEAL-4 and FINISH, you should see a most realistic effect.



I have just tested my procedure, and it seems to work quite well! You
can find the object, quickrenders of each state, and all the brushmaps
in the following web directory:

        http://www.interlog.com/~blaq/temp/RubberSheet

Note: while creating the object, I found that points covered by black
areas of the Applique map were still displaced. I had to go into each
state, click on a corner point to see how far unaffected points had
travelled, and translate all points by the opposite distance. If I
didn't do this, the base of the sheet would move backwards as the hand
pushed forward. The object on my web site has been corrected, but you'll
have to be careful when creating your own.

----------------------------------

Date:         Fri, 2 Jan 1998 03:44:21 -0600
From: CJO <[e-mail]>
Organization: Prodigy Internet

Hey thanks charles,
great tutorial thank you very much Im sure that took some time
the glow was the kicker.I was ending up  with the flat hand.
I jerked around with the dialate filter but of course it just distorted
the whole damn thing.the glow made all the diff in the world.
the other part of the anime (the head and shoulder area)are coming along
fine,except when the face first starts pushing through.I am not using
applique to do the face.instead I just deform and scale it to fit.
while the effect is very real,I cant seem to get thee right look
when the face first comes through the wall,I guess I could use the
applique for the first(not very detailed)few frames then switch over
to the deform tool to nail the look I want

anyway thank you for your time you have been a greate help

chris johnson

BTW what in the hell is bvre ?

----------------------------------

Date:         Fri, 2 Jan 1998 20:53:15 -0700
From: Seclusion <[e-mail]>

In my many fruitless, but plentiful Imagine experiments, I sort of cursed
when the black portions moved when using applique...then the answer hit me.

Especially if you have Photoshop, it's easy to fix.  Just Select the black
background and then select either 127 or 128 to replace it with.  Now, the
part I don't recall is which one works better (if either).

My confusion is caused by the inner workings of the computer...there's 256
colors, anything above 50/50 white/black will move one way, anything below
will move the other.  Seeeew, 50% of 256 is 128, but alas, the 256 color
components only total 255 in the minds of computers because absolute black
is 0.

Heh, ok, so maybe it's not so easy to fix, but it's a good workaround for
less than mammoth scaling applique projects...(how about a selective
applique, to only affect polygons when the colors in the appliquing image
are greater than -some number between 0 and 255-)

----------------------------------

Date:         Sat, 3 Jan 1998 12:34:57 +0400
From: Charles Blaquiere <[e-mail]>

Yep, for some reason Impulse decided that the neutral value would be
either 127 or 128. I assumed an Applique map value of zero would cause
zero displacement and 255 cause maximum displacement, but Impulse
preferred to displace points both positively and negatively. It must've
seemed logical to them at the time. I prefer my way, but this is a minor
issue, really, and as long as it's documented, I have no problem with
it.

As you suggest, one can simply use the 128-255 range rather than the
full 0-255 range when creating an Applique map, but the stickler in me
dislikes the decreased precision that comes from throwing away half the
possible values. Thus, I prefer creating Applique maps using the full
greyscale range, and later pick a point in Imagine, check how far it's
moved, and translate all points the opposite direction.

----------------------------------