Re:center/pivot was - XSI Montreal "Tips & Tricks" session, looking for presenters

["Tim Leydecker" <BauerOink(at)gmx.de>]

Hi Brent,

thanks for pointing out the differences between object pivot and center.

I had played with it a bit and *think* I got it to work as I´d need.
Still haven´t understood why there is a need to differentiate but
that´ll come with time I guess.

It´s pretty hard not to get confused and mix up terminology or
functionality, so I´ve put together two, three sampleworkflows
I´d like to easily go through without worrying about getting shifts
or loosing the option to enter/see correct values in the KP/L.

1)Animation:

Helperobject (like a nurbscircle) driving an IK chain, the chains object
pivot is centered, all values are zeroed out. Both [k]eying and numerical
entering a value in the KP/L produce similar results. The KP/L shows
reliable info, e.g. worldspaceposition.

2)Modeling:

Squeaky wheel, it´s object pivot set fixed to the rotation axis, scaling
the object numercially keeps it "in place".

Squeaky wheel, toggling COG on/off, allows to have selected every
2nd poly of the tires and either extrude outwards (Y) uniformly or,
when off, have the center sit on the extruded face (aligned) and move
it outwards numerically, either throught the extrude PPG or entering
the amount into the KP/L, e.g. KP/L would show the centervalues in
local space.

Currently, as the tools don´t take into account COG/refplane (it seems)
it´s difficult to first align the object pivot with a ref plane, then use a tool
like extrude to numercially extrude something correctly in a (local) axis.

Instead, the extrude seems to work based on the objectpivot, which isn´t
modified (and shouldn´t) but really should work based on the settings set
in the Transform panel, e.g. local(center or pivot?)/global (world?)/ref...

So, while you´re at it, would be cool to check for consistency, so that in
whatever mode, one could use the KP/L to enter a desired value (no shift),
extrude/use tool based on the currently set Transformpanel(space) options
(e.g. local space for component selections) and never worry about keying
the wrong values in the KP/L.

Cheers

tim






----- Original Message ----- 
From: "Brent McPherson" <brentmc(at)Softimage.COM>
To: <XSI(at)Softimage.COM>
Sent: Wednesday, May 31, 2006 8:54 PM
Subject: RE: XSI Montreal "Tips & Tricks" session, looking for presenters


> Tim,
>
> To scale an object with COG then you need to use the Scale command.
>
> However making the Transform panel input fields respect the COG setting is probably 
> a reasonable request. (but I would have to think about it some more...)
>
> If you want to easily set the pivot in XSI just turn on Transform -> Modify Object 
> Pivot. Now, using the Alt key in the transform tools will set the object's pivot. 
> (instead of just being used by the tool)
>
> In XSI, we have the concept of center *and* pivot. Center applies a translation to 
> your object and also applies an operator to shift the geometry in the opposite 
> direction. Therefore, you are probably better off sticking with the pivot and 
> avoiding the center. In addition to the interactive tools for setting the pivot it 
> can also be accessed through the local transform property page. (Ctrl+K)
> --
> Brent
>
> -----Original Message-----
> From: owner-xsi(at)Softimage.COM [mailto:owner-xsi(at)Softimage.COM] On Behalf Of Tim 
> Leydecker
> Sent: 31 May 2006 19:24
> To: XSI(at)Softimage.COM
> Subject: Re: XSI Montreal "Tips & Tricks" session, looking for presenters
>
> Hi Luc-Eric,
>
> I´m sorry if this sounds stupid but how would I get to scale that object (I did 
> with COG activated) uniformly and numerically precise without "shifting" it 
> offscreen?
>
> Why would I first have to "move center to vertices" or "freeze all transformations" 
> or "set neutral pose"?
>
> I imagined it has something to do with the center shifted off but shouldn´t this be 
> overridden by toggling let´s say COG on?
>
> I´d have thought any values entered are calculated relative to the currently set 
> coordinate system, how else could one get reliable results - if you´d always have 
> to do numerical input in Global space (>Display global values in view mode) only, 
> modeling in a differently set space can not be accurate.
>
> I see that for animation and especially plotting the absolute worldspace position 
> is important but even then when you animate scale something (using COG) but the 
> scaling is calculated in a different space, how do you know what value to add and 
> where?
>
> Maya is different in that respect as it only supports one mode, there´s no 
> differentiation between local and global, e.g. you couldn´t end up having two 
> different scale values but of course could shift an object when it´s center is 
> outside the BoundingBox.
> Maya will allways show the absolute scalefactor in the channelbox, if you scale 
> it´s based on the pivot - which is fixed until you change it while in XSI the 
> center(pivot) is constantly moving between spaces.
>
> Cheers
>
>
> tim
>
>
>
>
>
>
>
>
> ----- Original Message -----
> From: "Luc-Eric Rousseau" <lucer(at)Softimage.COM>
> To: <XSI(at)Softimage.COM>
> Sent: Wednesday, May 31, 2006 7:30 PM
> Subject: RE: XSI Montreal "Tips & Tricks" session, looking for presenters
>
>
> > > -----Original Message-----
> > > From: Tim Leydecker
> > >
> > > Hi Luc-Eric,
> > >
> > > I´ll see if I can put together a reproducable setup asap.
> > > ...
> > > Voilá. Got one. Sorry for attaching, my domain is down,
> > > seems my host (strato) is down, too. Can´t access my server.
> > >
> > > *.zip contains a *.scn file for XSI 5.1 Foundation.
> > >
> > > Select the wheel and scale it by entering 2 into
> > > the KP/L scale attributes, hit enter.
> > >
> > > Object jumps away. Scares me alot.
> >
> > Tim, objects scale around their centers, and you moved the
> > center of the object offscreen. In this particuliar case I
> > haven't found a particuliar setting that would change
> > Transform Panel's Scale edit boxes to do something other
> > than changing the local transform's scale, but if you expected
> > to scale around the center of the geometry that operation requires
> > changing more than 3 parameters of the scaling.  This is
> > what the manipulator does if you use it in COG mode.
> >
> > We'll probably add in the future a mini transform panel
> > in the keying panel area to add some flexibity with references,
> > but let's keep in mind the keying panel is meant for animating,
> > not for modeling, and isn't changing more parameters in your
> > back, or adding operators, the way that the Transform Panel is
> > to compensate for centers and references.  It's the 'true'
> > data of the object. It's exactly what you get in the maya channel
> > box, for example.
> >
> >
> > ---
> > Unsubscribe? Mail Majordomo(at)Softimage.COM with the following text in body:
> > unsubscribe xsi
>
>
> ---
> Unsubscribe? Mail Majordomo(at)Softimage.COM with the following text in body:
> unsubscribe xsi
>
> ---
> Unsubscribe? Mail Majordomo(at)Softimage.COM with the following text in body:
> unsubscribe xsi


---
Unsubscribe? Mail Majordomo(at)Softimage.COM with the following text in body:
unsubscribe xsi