pretransform is like a black box

[sanostol]

is there a way to make the pretransform values editable, it seems that you can only use the tools available in the parameters page. what if I want to ad a expression or just copy values to a other object

Martin

[michael]

you can extract the pretransform on the Transform Tab

and I believe there are expressions to access them...

>>exhelp objpretransform

personally I avoid pretransforms like the plague.

[sanostol]

I guess You use nulls instead, right?

you can extract the pretransform on the Transform Tab

and I believe there are expressions to access them...

>>exhelp objpretransform

personally I avoid pretransforms like the plague.

[michael]

generally...

then delete them with their children set to "Keep Pos When Parenting" when I send a rig to animation

[sanostol]

after working on, i tend to say pretransforms in the way right now are counterproductive and not very houdini like (just my opinion).

right now when I draw bones I remove the pretransform of the bones and repace it with nulls like michael suggested. but it means additional work. on the other hand the pretransforms are too far away to be edited in a convenient way. for example if You want to copy the pretransform of a allready animated object. i think it would be better if it may be editable like a real transform, maybe hidden by default but visible with the edit parameter interface. just a suggestion...

generally...

then delete them with their children set to "Keep Pos When Parenting" when I send a rig to animation

Edited September 1, 2009 by sanostol

[mrice]

Interesting, I'm kinda confused at what the problem with them is. Rather than a "black box" I see them part of the transformation stack, where under most cases you shouldnt need/want/be able to access them. For the cases where you do, cant you use expressions to grab the world transform, or make a shelf tool to do what you need, ie extracting the pretransform to a null and reparenting? What am I missing?

[graham]

I've got a tool kicking around that extracts and cleans any object pre-transforms and creates a parent null with those xforms as their parm transform that someone might find useful.

Edit: Replaced tarball with actual .shelf file.

obj_clean_prexform.shelf

Edited September 2, 2009 by graham

[edward]

right now when I draw bones I remove the pretransform of the bones and repace it with nulls like michael suggested. but it means additional work.

Once upon a time, having null objects in the middle of IK bone chains was disallowed. If you don't like the pre-transforms, you can always turn on Edit > Preferences > Objects and Geometry > Read-Only Pre-transforms. This will prevent Houdini from cleaning transforms.

[sanostol]

@ Graham: Thanks, very usefull tool. Thanks for sharing.

@ Edward: Thank You, good to know.

@ mrice: pretransform values seem just a bit to hard to reach. but the suggestions provided do the trick. my only thought was that the also could be just hidden values.

[anim]

having pre-transforms as editable parameters is very good idea

i find them like a black box too

for example in XSI you have them editable like another layer of transforms

it provides more control, you can animate them, set expressions on them, refer with expressions to them

very very helpful in rigging

in houdini i have to use another null parent

there is no problem with it, just i am not sure about the performance hit in complex rigs