# [Bf-committers] Delta Scale (patch to multiply rather then add).

Bassam Kurdali bassam at urchn.org
Sun Nov 27 23:16:39 CET 2011

```Question: I always assumed Delta Transforms were just one more
transformation matrix, multiplied by the base transform matrix of the
object. Am I incorrect?

Longer term, might be nicer than tweaking hard coded delta transforms,
to have a transform node graph (or stack) that encompasses multiple
transforms and constraints; That way would be nice for e.g. Offsets
(inverse parent/ child off/ constraint offsets - simplifying and making
more 'transparent' constraints) and for Delta transforms.

For the short term, it's interesting that objects have delta transforms
but bones don't (unless I miss anything)

On Mon, 2011-11-28 at 09:07 +1100, Campbell Barton wrote:
> On Mon, Nov 28, 2011 at 8:28 AM, Michael Fox <mfoxdogg at gmail.com> wrote:
> > ummm yeah, delta loc adds, delta rotation adds, so logically and
> > intuitively, delta scale should add,
>
> The idea of delta (from what I can tell) is to apply a difference in
> transform channels,
> rotation does not add - if you look at object_rot_to_mat3() it
> converts the rotations into a matrix and multiplies them together.
>
> If you want to double the existing 1.0 scaled object `intuitively`
> you'd set the delta to 2.0 right? :),
> like if the object was made the child of another object which was then
> scaled by 2.0x.
> But with adding delta scale this makes the object 3.0x, worse, you
> cant consistently double the existing scale, you always need to do
> some mental arithmetic to work out what double would be.
>
> Applying  scale to a point multiplies so IMHO its logical that delta
> scale would multiply too.
>
> Another downside of adding scale is you can get negative scales
> without meaning to (flipping the object), where as with multiplying as
> long as both are > 0.0 it wont happen.
>
> > multiplying is just going cause issues, when you scale something in the
> > UI, then it changes when you playback,
> >
> >  adding scale is more intuitive when animating, so you don't constantly
> > fret over what you are actually keying and that key is going to behave
> > properly when I playback
>
> don't understand why there would be any trouble here.
>
> > ass for the bug, delta scale when its being calculated just needs to
> > subtract by 1 that was scale of 1+0=1, changing it to multiply is just
> > too severe and heavy handed
>
> are you suggesting delta scale be modified to subtract 1 before being applied?
>
> > On 28/11/11 05:20, Campbell Barton wrote:
> >> This bug report highlights that delta scaling is adding rather then
> >> scaling the objects scale.
> >>
> >> https://projects.blender.org/tracker/index.php?func=detail&aid=29111&group_id=9&atid=498
> >>
> >> I've attached a patch which changes delta-scale to multiply to scale
> >> which IMHO is much more logical,
> >> incidentally do_displacement() in convertblender.c is already treating
> >> dsize as a multiplier which is odd.
> >>
> >> The patch attached to the bug report updates existing files with 2 caveats.
> >> - animated dsize wont be converted.
> >> - objects scaled to 0.0, with a non-zero delta scale can't be
> >> converted, think this is really an obscure case though.
> >>
> >> Would this be acceptable to apply before 2.61?
> >>
> >
> > _______________________________________________
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> >
>
>
>

```