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

Internet Message Format | 1998-02-28 | 17.1 KB

Date:         Sun, 21 Dec 1997 22:12:03 +0000
From: Nancy Jacobs <[e-mail]>
Subject:      [IML] QUEST: Particles puzzle

I have a few questions about the use of particles - perhaps someone
can answer some of them? I have IFW, CUP2

1. After I have assigned particles to an object, it always appears
with many particles around it, even in the detail editor. How do I
get these to disappear so that I can, say, see to choose a subgroup
or work on the object? I tried setting particles to FACES(off). I
even tried stripping the object of particles and saving it, loading
it back in and STILL the particles were everywhere. It seems that
the srtripping command doesn't work  Is  there some trick I'm
missing?

   Date:         Mon, 22 Dec 1997 18:44:16 +0000
   From: George Cole <[e-mail]>
   I tried using particles for the first time to help you but I came across
   no such problems. I use Imagine for Dos 4.0. When I used particles, they
   didn't appear at all in the Detail Editor, only when I rendered the
   object. FACES (off) means that you are using faces as the particles and
   so the object doesn't change.

2. When I used a simple Imagine object as my particle type, whenever
I render the object, it appears that one of the particles is
in the camera's face -that is, HUGE across the top of the screen,
taking up about half the pic - yet strangely enough, it is BEHIND one
of the objects (NOT the particle object) in the center of the scene.
What is occuring and/or how can I avoid this?

   Date:         Mon, 22 Dec 1997 18:44:16 +0000
   From: George Cole <[e-mail]>
   I did not come across this problem either. I only used quick renders but
   my objects seemed fine. If you have set the particle size to random then
   it could produce a very large particle. Try have the particle sizes as a
   set number.

3. I am attempting to make ray-like particles radiate out from a
circle of letters which are standing up and rotating. How do I get
the particles  to all fly straight off the circle outward - all
pointing out - and none going into the center? The particles always
seem to be pointing in the same direction no matter what setting I
use in the particles f/x. Anybody got the magic numbers?

   Date:         Mon, 22 Dec 1997 18:44:16 +0000
   From: George Cole <[e-mail]>
   Do you mean for the seed number? I think this only affects the particles
   if you are using a random setting for any of the options. I don't
   understand how this works but I don't think it should affect it that
   much. If your particles are custom made then just rotate the particle
   object in the detail editor and then save it. Reload the object you want
   to particlize and set the object you want to use as the particles again.

   Perhaps your problems are due to a IFW bug. Sorry I couldn't be much
   help.

   To everyone: I played with particles for 5 minutes but I came up with
   two interesting objects. Please have a look at :
   http://home.clara.net/cole/particles.html
   I don't like the first image but I think the curtain is quite nice. I
   remember seeing a nice particle object a while back on the list and
   would like to see others' work in particles. If you could send me an URL
   I'd be grateful.

Any pointers will be much appreciated!

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Date:         Mon, 22 Dec 1997 13:05:16 -0800
From: Bill Alexander <[e-mail]>

   <on point No. 1>

I did the same thing and mine worked fine.  Try it with a sphere object and
see if that works.  It worked fine for me, I turned them off and on again
with the faces off requester.  Also don't use the F-X particles, as I
believe from a past mistake where I used it instead, that one WILL turn the
object permanetly into a bunch of particles.

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Date:         Mon, 22 Dec 1997 19:55:27 +0000
From: Nancy Jacobs <[e-mail]>

Well, if I don't use particles f/x, then how do I get the object
to emit a continous stream of particles?

I've solved some of my questions (from oriiginal question), but in a
lot of experiments I've been doing, I end up with the particles
replacing the faces of the object as soon as I assign particles to it
in the detail editor. I would like to do the emission choice in the
particle f/x, where  the object is supposed to remain intact, but it
ain't workin because of the fact that the particles replace the faces
immediately as described above.

 I have IFW CUP2. Any ideas anyone?

It's good to be back on the list (and using Imagine) after a looong
semester away!

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Date:         Tue, 23 Dec 1997 00:12:34 -0500
From: "Martin J. Conlon" <[e-mail]>

You're using the particles stage effect in the detail editor.  That's why
the object is turning into particles immediately.  If you want your object
to stay normal, don't use the FX.  Just update the object's particle
attributes using the "Particle" (I think, don't have IFW in front of
me...) menu item.  In the dialog that pops up, you should be able to set
the particle types and their size and centering relative to their faces.
But *not* what they should be doing (emmitting, raining, bouncing, etc.)

Don't use the "Stage FX" menu item.  All of these FX's physically mold
your object, changing it forever (unless you hit "Undo".)  That's why it
asks you for a frame number or percentage complete.  It wants to know how
far along its normal animation sequence it should pretend it is.

The "Particles" emmission FX should be applied in the staging process.
Stage effects are designed to occupy one of the four FX slots in the
action dialog.

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Date:         Tue, 23 Dec 1997 06:24:26 -0500
From: gregory denby <[e-mail]>

Nancy Jacobs wrote:
>I end up with the particles
>replacing the faces of the object as soon as I assign particles to it
>in the detail editor.

I think that's just how it works. Once assigned particles, and object is,
well, a particle object. Hmm, come to think of it, I've never tried
making an object have a particles state... Nope, just tried it, and no
go, once particled, always particled.

>I would like to do the emission choice in the
>particle f/x, where  the object is supposed to remain intact,...

I seem to recall that the emissions setting used to keep the object
intact, but now, yes, the whole object fractures into particles. Perhaps
as a work around you could duplicate the object, no_part.iob, and have
it follow exactly the same path as pert_emit.iob?

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Date:         Wed, 24 Dec 1997 23:52:47 +0000
From: Nancy Jacobs <[e-mail]>

> > Well, if I don't use particles f/x, then how do I get the object
> > to emit a continous stream of particles?
>
> You're using the particles stage effect in the detail editor.  That's why
>  <<part cutted out>>
> But *not* what they should be doing (emmitting, raining, bouncing, etc.)
>

Hmmm.. How is that possible? I mean, to use the stage f/x in the
detail editor? All I know of there is the particles option under
functions. I just spotted "apply stage f/x" in the detail editor -
but I didn't use that one on the object which particlized. I only
used the particle function, and it still replaced the faces with
particles.

Come to think, that only happened with objects which were composed of
a single face thickness - like a string of planes. It didn't happen
to an object which had thickness (like a box). But with all the
objects you could see the particles right away in the detail editor.

Thanks to all for all the info - eventually I'll figure out what
happens when! Hearing from people on these things quickens that
process.

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Date:         Mon, 5 Jan 1998 20:37:06 +0400
From: Charles Blaquiere <[e-mail]>

I just tried (unsuccessfully) to get an acceptable "emanating rays"
effect using particles, after a couple of hours of effort. Urgh!

> So, I didn't much like the rays particle effect I had going anyway,
> so now I'm working on the disk idea I mentioned which had the spline
> interpolation problem, with textures simulating rays. It's better,
> but I'm still not there yet.
>
> Any bright ideas?

<laugh> Yes Nancy, I have one. I've uploaded an AVI (encoded using
Microsoft Video, I assume everyone has that encoder) to my web site:

        http://www.interlog.com/~blaq/temp/LightRays.avi

It shows a rotating logo spewing light rays in all directions. If you're
interested to know how I did it, let me know and I'll do a little
writeup.

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Date:         Tue, 6 Jan 1998 02:18:27 +0400
From: Charles Blaquiere <[e-mail]>

Stephen G. wrote:
>
> >        http://www.interlog.com/~blaq/temp/LightRays.avi
> >
> Yes, that's very nice please tell us how you did it.

Aargh, this was meant as a private reply to Nancy; I guess now I'm on
the hook for another tutorial. Tell you what; I'll post a quickie
description here, followed by a real tutorial at a later date.

The background is (almost) a disc (120 segments), placed vertically in
front of the camera, behind the other objects. I say "almost" because I
pulled the center point 5 units towards the camera, turning the disc
into a very flat cone. I rotated the cone's axis so its +Z points
towards the camera, then wrapped two brushmaps on it: a color brushmaps
(the streaks on a black background) and a filter brushmap (a greyscale
version, reversed to get a white background -- white = full filter).

Now here's the kicker: I wrapped the brushmaps in a cylinder around Z,
and stretched the brushmap Z to about 100 units, or 20 times the cone's
height. This means that, at any point in time, the cone will only
display a slice of the brushmap.

I created two states: START, where the brushmap axes are about +99
units  in local Z, relative to the cone axis; and END, where the
brushmaps are about -0.1 units in local Z, relative to the cone axis.
When animated from START to END, the brushmaps will sweep over the cone,
making the texture move through the object.

   Date:         Tue, 6 Jan 1998 20:26:59 +0400
   From: Charles Blaquiere <[e-mail]>
   Silly me. The brushmap positions, in local X relative to the object
   axis, are:
          START   about -0.1
          END     about -99

Because of its shape, the texture will seem to start at the center of the
background, then move outwards in all directions:

   Brushmap                        Cone (side view)
+--------------+                                         _
|11111111111111|                                      _--1--_
|22222222222222|                 _                 _--2222222--_
|33333333333333|              _--3--_           *==-33333333333-==*
|44444444444444|           _--4444444--_
|55555555555555|        *==-55555555555-==*
+--------------+

                               START                    END

See how the pattern on brushmap line #3, which is squeezed into the
center of the background (the cone, when seen from its top) at START,
has moved to the outside of the cone by the time we reach the END state?
(Actually, the cone remains stationary, it's the brushmaps that move --
but having the cone move made for a much clearer ASCII diagram)

Since the cone's height is only 1/20 that of the texture axis, at any
time, the cone will display a horizontal slice of the brushmap, 1/20 its
height. The brushmap starts has empty areas at the top and bottom, to
give me a background free of any streaks, at the beginning and end of
the animation. (The AVI posted is only the first half of the animation)

By varying the cone's height (i.e. dragging the center point), you can
make it display a larger or smaller portion of the brushmap. A larger
portion means that the streaks will look shorter, and move slower. The
same could be achieved by making a brushmap with less pixels in the
vertical dimension. The horizontal pixel size determines how many
streaks could fit into a full 360-degree circle when the image is mapped
onto the object. Less pixels would make the streaks thicker.


This flattened cone object is one of my best friends: it converts a
rectangular brushmap into polar coordinates. It can be used anytime I
want a radial effect: vertical lines on the brushmap become streaks,
horizontal elements become circles -- this means I can enter text on the
brushmap and have it appear in a circle in Imagine!

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Date:         Fri, 9 Jan 1998 11:48:40 +0000
From: Nancy Jacobs <[e-mail]>

Just got your post - I've been painting pictures in the basement for
a few days.....

Your light rays have definite possibilities, Charles! I
prefer it to anything I've come up with so far. One question, cause I
don't have time to work through your tutorial just yet (and see if I
understand it correctly) - Do you think this will work for a
horizontal disk plane? I see yours is vertical, and I need a
horizontal orientation. Any adjustments (besides the obvious) that
you think might be needed? For example, would you keep the axis
orientations as you have them (including the z wrap) and just rotate
the whole thing to be horizontal, or would you have to change the
axis orientation to get this to work?

A question - when you say rotate the cone's axis so z points toward
the camera, do you mean rotate the whole cone - or just the axis? Do
you want to end up with the cone AND the axis pointing toward the
camera? (seems that way) . Also, I'm not sure I get the states
portion of your explanation (I confess to never having used
states...) Anything I might be likely to miss as a newbie in that
area?

Looks like I could be on my way to some decent rays..

Thanks much!

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Date:         Fri, 9 Jan 1998 14:22:42 +0400
From: Charles Blaquiere <[e-mail]>

I agree! You can do _a lot_ with radial-type animated backgrounds.

Actually, the cone's axis doesn't matter; it's really the brushmap axes
that count, since they define how the brushmaps will be wrapped onto the
object. Here's how it would look in your case, where your camera is
pointing down at the scene:

FRONT VIEW
----------
             O  camera
             |

     +----------------+
     |                |  logo (see P.S.)
     +----------------+

     +----------------+  black disc (see P.S.)

             z
          _--^--_  cone
       _--   |   --_
     --------+--------


The flat cone is aligned with its point aimed right at the camera, and
the Z axis of its brushmaps runs from bottom to top. (Because of its
proportions, the cone's axes would have dimensions similar to 50,50,5 or
something) Again, the Z axis pictured is not the cone's, but that of the
brushmaps.

> Also, I'm not sure I get the states
> portion of your explanation (I confess to never having used
> states...) Anything I might be likely to miss as a newbie in that
> area?

Apply the brushmaps so that your cone is lying, in the Front and Right
views, at the bottom of "brushmap space" (the maps' bounding box), i.e.
that the base of the cone is juuuuust above the brushmap axes (in local
Z). Pick the cone object once you've applied the brushmaps, and
States/States/Create the DEFAULT state, with only the Textures/Brushes
checkbox activated. (All states in this example use the same checkbox
settings) Then States/States/Create a START state.

This is needed because, when using states _in an animation_, you must
_never_ use the DEFAULT state in any Action bar. That's why we create an
exact duplicate (here named START) to be used later on.

You then move both brushmap axes so that the cone now lies at the top of
"brushmap space", i.e. its top is juuuust below the end of the
brushmaps'  +Z axis. Then States/Create/Create the END state and save
the object.

After bringing the object into the Stage Editor, open the Action Dialog
and alter the cone's Actor channel so that you have a 1-frame Actor bar
in which the "State" field contains "START" (use the Browse button, it's
easier), immediately followed by a (n-1)-frame Actor bar where the
selected state is END. This is nothing new to you: it's the standard way
to set up an Imagie morph. In this case, Imagine will morph the object
from one state to another, and since the only thing that changes is the
position of the brushmap axes relative to the cone, the brushmap images
will appear to flow along the faces of the cone, giving rise to the
light rays' motion.

P.S. the logo and black disc aren't specifically part of the recipe for
radially-animated backgrounds, but are part of the project you are
working on.

In the AVI I created, I didn't want the rays to emanate from the center
of the screen; I believe that's not the effect you're after either. So,
I placed the light ray cone at the back of the scene, and loaded a black
disc in front. The disc is black with 0% filter, but has a Radial
texture set to feather its edges into invisibility. (Params: Color,
Reflect = black, Filter = white, Start Radius = 80% of the object
radius, and Transition Width = 19.9% of object radius) This creates a
black disc whose edge gradually becomes transparent. I sized the black
disc to the same size as the logo. This hides the light rays from the
center of the screen, and lets them progressively appear behind the
logo. Look again at the AVI
(http://www.interlog.com/~blaq/temp/LightRays.avi) to see the subtle
effect.

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