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From: Rune
Subject: Re: Walking Along a Path WIP1
Date: 22 Oct 2001 18:29:14
Message: <3bd4657a@news.povray.org>
"Greg M. Johnson" wrote:
> I fear that my algo for foot placement is totally
> different from yours:  I have a system which will
> allow easy switches (different movement parameter
> files) between say walking, running, stair
> climbing. I don't want to tamper with it this far
> down the road.

You're right, the walk cycles need to be rewritten completely in order to
adapt them to my system. I will also have to do that with my own walk
cycles. I intent to do that, but I also have the advantage that I know the
technique well.

> I'm trying to decide whether to do this or get more
> realistic hands & fingers.

Go with whatever you feel like. That's what I always do anyway... :)

> I was inspired by this "walking on a curve" concept after
> reading in a 3d magazine where some genius programmed
> people walking in "flocks": they ambled through a crowd,
> avoiding neighbors while going on a basically circular,
> random path.

Hmm, I could do that I guess. I've done flying flocking algorithms before,
and it shouldn't be too difficult to adapt it to walking creatures. Not
right now, but once I get better control over this walking technique, I
might give it a shot. :)

Rune
--
3D images and anims, include files, tutorials and more:
Rune's World:    http://rsj.mobilixnet.dk (updated June 26)
POV-Ray Users:   http://rsj.mobilixnet.dk/povrayusers/
POV-Ray Webring: http://webring.povray.co.uk


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From: Greg M  Johnson
Subject: Re: Walking Along a Path WIP1
Date: 22 Oct 2001 21:17:18
Message: <3BD48C8A.5718AB13@aol.com>
1) That WalkPath is a spiral; it seemed to me like your anim was of an
intersecting loop.

2) Regarding your help to TonyB's idea for a new blobmon.  On January
13, 2001, I posted an anim of a system I'll give away in a heartbeat.
 http://news.povray.org/3a6e4923%40news.povray.org

It has:
a) FK & IK capabilities for both hands & arms.
b) construction based on painstaking copying of coordinates from
anatomical skeletons
c) pose/walk-parameter-file   and   object-parameter-file  capability
built in.
d) body parts move via transforms thus allowing blobs or CSG or
whatever.

I showed off its mobility with a cocky, freaky looking anim and some of
the reactions were probably to its freakiness moreso than its technical
achievement.

Then only catch as written is that the user  have to declare a
headobject, forearmobject, etc. Good for versatility, a pain to model,
especially to the precise scale my system required.  Hence I set aside
this version.  I feel more "ownership" over my more recent creation,
which is less technically astounding, but has more personality to the
blob face I've spent so much time on: hence I'd readily give away this
technically advanced skeleton for your helping along TonyB's project....

Rune wrote:

> "Greg M. Johnson" wrote:
> > Okay, but first of all, you have a totally different
> > "path" in the code you posted THERE than in the anim
> > you posted HERE, yes?
>
> No, in fact they're exactly the same. By "path" I mean this:
>
> // The path to follow:
> #macro WalkPath (Time)
>    vrotate(Time*x,180*Time*y)
> #end


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From: Rune
Subject: Re: Walking Along a Path WIP1
Date: 22 Oct 2001 21:40:23
Message: <3bd49247@news.povray.org>
"Greg M. Johnson" wrote:
> 1) That WalkPath is a spiral; it seemed to me like
> your anim was of an intersecting loop.

Guess what happens if you draw a spiral from the outside towrds the center
and continues to draw after you've reached the center. In the middle of the
spiral you'll get an intersecting loop! (The Time value doesn't start at
zero, but from a negative value.) :)

> 2) Regarding your help to TonyB's idea for a new blobmon.
>    On January 13, 2001, I posted an anim of a system I'll
>    give away in a heartbeat.
>    http://news.povray.org/3a6e4923%40news.povray.org

I'll have a look at it, but if I use it it will probably be bits and bytes
here and there rather than the whole thing, as I have specific plans for the
system.

> It has:
> a) FK & IK capabilities for both hands & arms.

This could maybe be used as one of the alternative posing interfaces.

> b) construction based on painstaking copying of
>    coordinates from anatomical skeletons.

I'll have a good look at that!

> d) body parts move via transforms thus allowing blobs or
>    CSG or whatever.

Naturally that's how I've been working all the way too, as it's the only
method flexible enough. :)

> Then only catch as written is that the user have to
> declare a headobject, forearmobject, etc. Good for
> versatility, a pain to model

I may be able to come up with workarounds to this. Or at least tips and
tricks how to ease the modeling.

Thanks for your contribution.

Rune
--
3D images and anims, include files, tutorials and more:
Rune's World:    http://rsj.mobilixnet.dk (updated June 26)
POV-Ray Users:   http://rsj.mobilixnet.dk/povrayusers/
POV-Ray Webring: http://webring.povray.co.uk


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From: Greg M  Johnson
Subject: Re: Walking Along a Path WIP1
Date: 23 Oct 2001 14:52:40
Message: <3BD583DC.1FC14068@aol.com>
Rune wrote:

> I'll have a look at it, but if I use it it will probably be bits and bytes
> here and there rather than the whole thing, as I have specific plans for the
> system.

See p.b.s-f.
The mime25 file is actually quite hideous.  (I only later realized that the
transforms could work WITHIN the blob.)...


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From: Reusser
Subject: Re: Walking Along a Path WIP1
Date: 23 Oct 2001 23:15:48
Message: <231020011810105072%reu1000@chorus.net>
In article <3bd09499@news.povray.org>, Rune wrote:

> But later on when I need more complex motion I'll probably use the cubic
> splines in POV-Ray 3.5 despite the limitations. I only hope that the bugs
> will soon be fixed.

I've been too busy with homework to really keep up on everything, so I
haven't heard all about the limitations of splines in 3.5, but I have a
question about how you would accomplish this.  How would you keep the
motion at a constant speed?  Splines generally do not have a constant
velocity vector along them.  Wouldn't a cubic spline make the walk/run
speed up and slow down?  Would the character go from a walk to a run as
it speeds up?

 - Rico


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From: Rune
Subject: Re: Walking Along a Path WIP1
Date: 24 Oct 2001 12:59:03
Message: <3bd6bb17@news.povray.org>
"Reusser" wrote:
> How would you keep the motion at a constant speed?
> Splines generally do not have a constant velocity
> vector along them.  Wouldn't a cubic spline make
> the walk/run speed up and slow down?

Since splines allows to adjust both control points and time values, it's
often possible to tweak a spline to be somewhat constant in speed.

However, when people walk they don't keep constant speed. Every time one
starts or stops walking or when turning in a curve the speed of the walk
changes. When one goes from walk to run or things like that the speed also
changes.

> Would the character go from a walk to a run as it
> speeds up?

Yes, that's the idea. Not implemented yet though, but I'm working on it.

Rune
--
3D images and anims, include files, tutorials and more:
Rune's World:    http://rsj.mobilixnet.dk (updated June 26)
POV-Ray Users:   http://rsj.mobilixnet.dk/povrayusers/
POV-Ray Webring: http://webring.povray.co.uk


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From: John VanSickle
Subject: Re: Walking Along a Path WIP1
Date: 24 Oct 2001 20:40:47
Message: <3BD728FF.20917112@hotmail.com>
> I'm working on such techniques. The attached animation is a very early
> test. Never mind the crude model and the simplified walk motion. What
> matters right here is the basic functionality that makes the feet
> follow the spline and move them nicely from one position to another
> with no slippage.

The Greb, TC and Joe from my IRTC entries use a combination of
macros to accomplish walking.

The overall one takes two splines, a given time, an offset into the
spline, an upper and lower bound, the step length, the time needed to
make the step, the time to wait between steps, the up direction, and
the offset of the foot's place from the path, and from this generates
the location of the foot at any given time.

I use two splines, one for the direction the model is walking and the
other for the direction the model is facing as it walks, so that
models can walk sideways, backwards, and turn as they walk.

Simulating a human walk is much more ambitious...

Regards,
John
-- 
ICQ: 46085459


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From: Greg M  Johnson
Subject: Re: Walking Along a Path WIP1
Date: 24 Oct 2001 21:14:39
Message: <3BD72F08.BD1CF9EE@aol.com>
John VanSickle wrote:

> I use two splines, one for the direction the model is walking and the
> other for the direction the model is facing as it walks, so that
> models can walk sideways, backwards, and turn as they walk.

Could you please post the code for a typical walk path?  Everyone's own
walking figures will work differently, but I'm at the square one of how to
define a curve that is smooth in povray.  Also, are you able to determine
the path length between two points on your path?

I had my own run-ins with splines and heard about the 3.5 bugs so I have
have had this on the back shelf.


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From: Rune
Subject: Re: Walking Along a Path WIP1
Date: 25 Oct 2001 12:58:07
Message: <3bd80c5f@news.povray.org>
"John VanSickle" wrote:
> The overall one takes two splines, a given time,
> an offset into the spline, an upper and lower bound,
> the step length, the time needed to make the step,
> the time to wait between steps, the up direction,
> and the offset of the foot's place from the path,
> and from this generates the location of the foot at
> any given time.

Sounds very similar to my approach in several aspects.

Things that may differ:

Your method takes an offset into the spline - with my macro this is a
property of the spline, i.e. for a given time value a given point is
returned.

Your method takes a step length - with mine the step length is variable, and
gets longer at higher speeds. Of course you can specify the time/length
relation, but it will always adjust to the speed of the spline. How does
your method work with regard to variable speed walking?

> I use two splines, one for the direction the model is
> walking and the other for the direction the model is
> facing as it walks, so that models can walk sideways,
> backwards, and turn as they walk.

That's funny, I've been planning to do exactly the same!

> Simulating a human walk is much more ambitious...

Well, I'm aiming for a general solution that can be used for practically any
walking thing, from humans to animals to weird robots...

I'd be interested in hearing more details about your approach! :)

Rune
--
3D images and anims, include files, tutorials and more:
Rune's World:    http://rsj.mobilixnet.dk (updated June 26)
POV-Ray Users:   http://rsj.mobilixnet.dk/povrayusers/
POV-Ray Webring: http://webring.povray.co.uk


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From: John VanSickle
Subject: Re: Walking Along a Path WIP1
Date: 27 Oct 2001 11:32:28
Message: <3BDA9D06.CBFACD1B@hotmail.com>
Rune wrote:
> 
> Sounds very similar to my approach in several aspects.
> 
> Things that may differ:
> 
> Your method takes an offset into the spline - with my macro this is a
> property of the spline, i.e. for a given time value a given point is
> returned.

Sometimes the walk starts from a position where the feet are all
regularly arranged, but during the walk the arrangement is not regular.
For example, TC has five feet.  To make them move right, the first one
to move moves only a little bit on its first step.  The next one takes
a larger step, and so on, until the fifth foot (and all subsequent
steps) are full sized steps.  At the end of the walk the process is
reversed, so that all five feet come to rest in a regular arrangement.

> Your method takes a step length - with mine the step length is
> variable, and gets longer at higher speeds. Of course you can specify
> the time/length relation, but it will always adjust to the speed of
> the spline. How does your method work with regard to variable speed
> walking?

The step length actually refers to the difference between two indices
into the spline.  The spline can be one with a fairly consistent
velocity throughout, or variable.  The actual size of the steps taken
varies according to this.  For the splines I'm using now the speed
at any given point is about 1.

> > I use two splines, one for the direction the model is
> > walking and the other for the direction the model is
> > facing as it walks, so that models can walk sideways,
> > backwards, and turn as they walk.
> 
> That's funny, I've been planning to do exactly the same!

It appears to be the easiest way to solve the problem.

> > Simulating a human walk is much more ambitious...
> 
> Well, I'm aiming for a general solution that can be used for
> practically any walking thing, from humans to animals to weird
> robots...
> 
> I'd be interested in hearing more details about your approach! :)

I guess I ought to release the code, once I get it idiot-proof enough
for public viewing.  I might see if I can make the walk macro use
the splines that Chris put out, so that there would be less confusion.

Regards,
John
-- 
Rusty is rendering!


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