Re: [openjdk/jfx] 8234712: Add pivot properties for scale and rotation in Node, ScaleTransition and RotateTransition (#53)

[Nir Lisker]

I was thinking about this some more. We could use ObjectProperty as
this would allow to set nulls in order to reset the value to the default
node's center, and will allow independent axis control and binding. It's
rather ugly though in my opinion.

On Tue, Dec 17, 2019 at 2:46 AM Nir Lisker  wrote:

> As long as you do the following, it should work as expected:
>>
>> T(pivotRot) * T(rotate) * T(-pivotRot) * T(pivotScale) * T(scale) *
>> T(-pivotScale) * object coords
>>
>
>  I think that this is what the PR does already. Line 5061 onward is:
>
> localToParentTx = localToParentTx.deriveWithTranslation(rotPivotX,
> rotPivotY, rotPivotZ)
>  .deriveWithRotation(rotAngle, rotAxisX,
> rotAxisY, rotAxisZ)
>  .deriveWithTranslation(-rotPivotX,
> -rotPivotY, -rotPivotZ);
> ...
> localToParentTx = localToParentTx.deriveWithTranslation(scalePivotX,
> scalePivotY, scalePivotZ)
>  .deriveWithScale(getScaleX(),
> getScaleY(), getScaleZ())
>  .deriveWithTranslation(-scalePivotX,
> -scalePivotY, -scalePivotZ);
>
> On Tue, Dec 17, 2019 at 2:07 AM Kevin Rushforth <
> kevin.rushfo...@oracle.com> wrote:
>
>>
>>
>> On 12/15/2019 6:06 PM, Nir Lisker wrote:
>>
>> Replying on the mailing list to the questions raised on GitHub.
>>
>> The state of whether to use the computed center pivot or the value of the
>>> pivot attribute is implicit with no way for an application to know which it
>>> is, and no way to set it back to using the computed center (i.e., the state
>>> is sticky once you set it). Perhaps if you defined a null value as meaning
>>> "computed center" then an app could at least reset it to the "computed
>>> center" state, although there would still be no way for the app to know
>>> that it was in that state.
>>>
>>
>> In the JBS issue  I
>> alluded to this in point 5. I think that null should represent the default
>> (node center). However, if we use 3 doubles instead of a Point3D we might
>> need to use Double.NaN for this instead, which would also be the default
>> for this case. The docs will explain this.
>>
>>
>> Using Double.NaN as an out of band value would be odd, and probably not
>> what we want. In addition to the fact that it is somewhat artificial, it
>> would mean that X, Y, and Z would independently be treated as coming from
>> the set value or from the computed center. I guess this is one argument for
>> using a Point3D object, but as you note, there are other drawbacks.
>>
>> Do we need separate properties for scale pivot and center pivot?
>>>
>>
>> I say yes, otherwise the enhancement will be very limited. I think of
>> this enhancement as adding pivot control to Rotate/Scale transitions, and
>> adding them to Node is a necessary (and desirable) step.
>>
>>
>> Yeah, I figured this was the case.
>>
>>... you need to worry about what coordinate space the rotation pivot
>>> is defined in. Perhaps if the rotation pivot were defined in unscaled
>>> space, it might work.
>>>
>>
>> Isn't it already? If I set the rotation pivot to the edge of the node,
>> then scale it down, then rotate, the rotation pivot would be outside of the
>> node's boundaries. In scaled space it would still be on the edge. Or did I
>> misunderstand you?
>>
>>
>> I think I was wrong in the comment I added to the PR.
>>
>> What I meant is that you would need to define the coordinate space that
>> the pivot values are in, and it needs to be defined in a way that it is
>> consistent with current behavior. Today, the part of the matrix
>> transformation that does the scale and rotate, including the computed
>> pivot, is this:
>>
>> T(pivot) * T(rotate) * T(scale) * T(-pivot) * object coords
>>
>> As long as you do the following, it should work as expected:
>>
>>
>> T(pivotRot) * T(rotate) * T(-pivotRot) * T(pivotScale) * T(scale) *
>> T(-pivotScale) * object coords
>>
>> Importantly, this will work exactly as it does today when pivotRot ==
>> pivotScale which is the case I was most concerned about.
>>
>> In any case, I don't think that there's a single correct answer here.
>>
>>
>> It needs to be consistent with current behavior, and match what an
>> application would expect. I think it should not be a problem if defined as
>> above.
>>
>> Should the pivot be specified as a Point3D or 3 separate doubles?
>>> Separate doubles... there would be no out-of-band null value to use
>>
>>
>> See my point above about Double.NaN.
>>
>>
>> OK, there is no "natural" out of band value that is likely to be
>> satisfying. We'd probably end up wanting a boolean that controls computed
>> versus explicit (either a single flag or one for each of scalePivot and
>> rotatePivot)
>>
>> The doubles vs Point3D is an important choice. We might want to look into
>> the future even where Point3D (and 2D) could be made into an Inline class
>> with Valhalla, which will help with t

Re: [openjdk/jfx] 8234712: Add pivot properties for scale and rotation in Node, ScaleTransition and RotateTransition (#53)

[Nir Lisker]

>
> As long as you do the following, it should work as expected:
>
> T(pivotRot) * T(rotate) * T(-pivotRot) * T(pivotScale) * T(scale) *
> T(-pivotScale) * object coords
>

 I think that this is what the PR does already. Line 5061 onward is:

localToParentTx = localToParentTx.deriveWithTranslation(rotPivotX,
rotPivotY, rotPivotZ)
 .deriveWithRotation(rotAngle, rotAxisX,
rotAxisY, rotAxisZ)
 .deriveWithTranslation(-rotPivotX,
-rotPivotY, -rotPivotZ);
...
localToParentTx = localToParentTx.deriveWithTranslation(scalePivotX,
scalePivotY, scalePivotZ)
 .deriveWithScale(getScaleX(), getScaleY(),
getScaleZ())
 .deriveWithTranslation(-scalePivotX,
-scalePivotY, -scalePivotZ);

On Tue, Dec 17, 2019 at 2:07 AM Kevin Rushforth 
wrote:

>
>
> On 12/15/2019 6:06 PM, Nir Lisker wrote:
>
> Replying on the mailing list to the questions raised on GitHub.
>
> The state of whether to use the computed center pivot or the value of the
>> pivot attribute is implicit with no way for an application to know which it
>> is, and no way to set it back to using the computed center (i.e., the state
>> is sticky once you set it). Perhaps if you defined a null value as meaning
>> "computed center" then an app could at least reset it to the "computed
>> center" state, although there would still be no way for the app to know
>> that it was in that state.
>>
>
> In the JBS issue  I
> alluded to this in point 5. I think that null should represent the default
> (node center). However, if we use 3 doubles instead of a Point3D we might
> need to use Double.NaN for this instead, which would also be the default
> for this case. The docs will explain this.
>
>
> Using Double.NaN as an out of band value would be odd, and probably not
> what we want. In addition to the fact that it is somewhat artificial, it
> would mean that X, Y, and Z would independently be treated as coming from
> the set value or from the computed center. I guess this is one argument for
> using a Point3D object, but as you note, there are other drawbacks.
>
> Do we need separate properties for scale pivot and center pivot?
>>
>
> I say yes, otherwise the enhancement will be very limited. I think of this
> enhancement as adding pivot control to Rotate/Scale transitions, and adding
> them to Node is a necessary (and desirable) step.
>
>
> Yeah, I figured this was the case.
>
>... you need to worry about what coordinate space the rotation pivot is
>> defined in. Perhaps if the rotation pivot were defined in unscaled space,
>> it might work.
>>
>
> Isn't it already? If I set the rotation pivot to the edge of the node,
> then scale it down, then rotate, the rotation pivot would be outside of the
> node's boundaries. In scaled space it would still be on the edge. Or did I
> misunderstand you?
>
>
> I think I was wrong in the comment I added to the PR.
>
> What I meant is that you would need to define the coordinate space that
> the pivot values are in, and it needs to be defined in a way that it is
> consistent with current behavior. Today, the part of the matrix
> transformation that does the scale and rotate, including the computed
> pivot, is this:
>
> T(pivot) * T(rotate) * T(scale) * T(-pivot) * object coords
>
> As long as you do the following, it should work as expected:
>
>
> T(pivotRot) * T(rotate) * T(-pivotRot) * T(pivotScale) * T(scale) *
> T(-pivotScale) * object coords
>
> Importantly, this will work exactly as it does today when pivotRot ==
> pivotScale which is the case I was most concerned about.
>
> In any case, I don't think that there's a single correct answer here.
>
>
> It needs to be consistent with current behavior, and match what an
> application would expect. I think it should not be a problem if defined as
> above.
>
> Should the pivot be specified as a Point3D or 3 separate doubles?
>> Separate doubles... there would be no out-of-band null value to use
>
>
> See my point above about Double.NaN.
>
>
> OK, there is no "natural" out of band value that is likely to be
> satisfying. We'd probably end up wanting a boolean that controls computed
> versus explicit (either a single flag or one for each of scalePivot and
> rotatePivot)
>
> The doubles vs Point3D is an important choice. We might want to look into
> the future even where Point3D (and 2D) could be made into an Inline class
> with Valhalla, which will help with the performance aspect. Binding to one
> of the coordinates is sill a problem there, however.
>
>
> I think this (doubles vs Point3D) is really the main question. I don't
> know what the best answer is, but I'd like to hear from other developers.
>
> -- Kevin
>
>
> On Sat, Dec 14, 2019 at 6:25 PM Kevin Rushforth 
> wrote:
>
>> This will need discussion on the openjfx-dev mailing list. Here are the
>> questions that need to be resolved:
>>
>>1.
>>
>>  

Re: [openjdk/jfx] 8234712: Add pivot properties for scale and rotation in Node, ScaleTransition and RotateTransition (#53)

[Kevin Rushforth]

On 12/15/2019 6:06 PM, Nir Lisker wrote:

Replying on the mailing list to the questions raised on GitHub.

The state of whether to use the computed center pivot or the value
of the pivot attribute is implicit with no way for an application
to know which it is, and no way to set it back to using the
computed center (i.e., the state is sticky once you set it).
Perhaps if you defined a null value as meaning "computed center"
then an app could at least reset it to the "computed center"
state, although there would still be no way for the app to know
that it was in that state.


In the JBS issue  I 
alluded to this in point 5. I think that null should represent the 
default (node center). However, if we use 3 doubles instead of a 
Point3D we might need to use Double.NaN for this instead, which would 
also be the default for this case. The docs will explain this.


Using Double.NaN as an out of band value would be odd, and probably not 
what we want. In addition to the fact that it is somewhat artificial, it 
would mean that X, Y, and Z would independently be treated as coming 
from the set value or from the computed center. I guess this is one 
argument for using a Point3D object, but as you note, there are other 
drawbacks.



Do we need separate properties for scale pivot and center pivot?


I say yes, otherwise the enhancement will be very limited. I think of 
this enhancement as adding pivot control to Rotate/Scale transitions, 
and adding them to Node is a necessary (and desirable) step.


Yeah, I figured this was the case.


 ... you need to worry about what coordinate space the rotation
pivot is defined in. Perhaps if the rotation pivot were defined in
unscaled space, it might work.


Isn't it already? If I set the rotation pivot to the edge of the node, 
then scale it down, then rotate, the rotation pivot would be outside 
of the node's boundaries. In scaled space it would still be on the 
edge. Or did I misunderstand you?


I think I was wrong in the comment I added to the PR.

What I meant is that you would need to define the coordinate space that 
the pivot values are in, and it needs to be defined in a way that it is 
consistent with current behavior. Today, the part of the matrix 
transformation that does the scale and rotate, including the computed 
pivot, is this:


    T(pivot) * T(rotate) * T(scale) * T(-pivot) * object coords

As long as you do the following, it should work as expected:


    T(pivotRot) * T(rotate) * T(-pivotRot) * T(pivotScale) * T(scale) * 
T(-pivotScale) * object coords


Importantly, this will work exactly as it does today when pivotRot == 
pivotScale which is the case I was most concerned about.



In any case, I don't think that there's a single correct answer here.


It needs to be consistent with current behavior, and match what an 
application would expect. I think it should not be a problem if defined 
as above.



Should the pivot be specified as a |Point3D| or 3 separate
doubles? Separate doubles... there would be no out-of-band
|null| value to use

See my point above about Double.NaN.


OK, there is no "natural" out of band value that is likely to be 
satisfying. We'd probably end up wanting a boolean that controls 
computed versus explicit (either a single flag or one for each of 
scalePivot and rotatePivot)


The doubles vs Point3D is an important choice. We might want to look 
into the future even where Point3D (and 2D) could be made into an 
Inline class with Valhalla, which will help with the performance 
aspect. Binding to one of the coordinates is sill a problem there, 
however.


I think this (doubles vs Point3D) is really the main question. I don't 
know what the best answer is, but I'd like to hear from other developers.


-- Kevin


On Sat, Dec 14, 2019 at 6:25 PM Kevin Rushforth 
mailto:notificati...@github.com>> wrote:


This will need discussion on the openjfx-dev mailing list. Here
are the questions that need to be resolved:

1.

The state of whether to use the computed center pivot or the
value of the pivot attribute is implicit with no way for an
application to know which it is, and no way to set it back to
using the computed center (i.e., the state is sticky once you
set it). Perhaps if you defined a null value as meaning
"computed center" then an app could at least reset it to the
"computed center" state, although there would still be no way
for the app to know that it was in that state.

2.

Do we need separate properties for scale pivot and center
pivot? A single pivot property would be easier to define, but
wouldn't allow you to set it from a |RotationTransition| and a
|ScaleTransition| if you wanted to apply both to the same
|Node|. With two separate properties, as you have defined it,
it is more flexibl

Re: [openjdk/jfx] 8234712: Add pivot properties for scale and rotation in Node, ScaleTransition and RotateTransition (#53)

[Nir Lisker]

Thanks for the input Michael,


> Introducing two separate centers for rotation and scaling is, to my
> opinion, just academic without any practical use-case and in the end much
> more complicated for the user.


I have a practical use case in my app. I assume that the people who
requested these enhancements also had one. I also don't think that it's
"much" more complicated as it just aligns with the existing transforms
functionality.

1. Three doubles always use their full space even if you don't need them.


No sure what you mean by "full space". Properties are initialized lazily,
so if a value was not set, the reference is null, and the default pivot
value applies (computed center).

2. Using Double.NaNs as a switch between computed and user-provided
> center is just confusing and error-prone.


It is confusing indeed, but I don't think it's error prone as you'd be hard
pressed to fall on a NaN value for a pivot point as a result of a
computation. We could use one of the INFINITY values instead if it's
better. We should create a constant, public static final double CENTER =
Double.NaN (placeholder name), just like Animation.INDEFINITE = -1,
Region.USE_PREF_SIZE
= Double.NEGATIVE_INFINITY, Region.USE_COMPUTED_SIZE = -1 etc. It's not
ideal, but it's a solution for allowing the user to revert to the default
behavior without additional boolean properties.


> What would be the meaning of setting x to some value but leaving y and z
> as NaN?
>

That y and z are the computed center (Node computes the x, y and z of the
center separately to being with), and x is the user value.

I bet most users will forget to set the Z-value anyway if they are thinking
> 2D.


They wouldn't need to, it will behave as it does now (overall, backwards
compatibility is guaranteed).


> A simple null value is much easier to handle and explain.


Yes, it's certainly an advantage of a Point3D, which was my initial
implementation. The main issue with it, I would say, is that it's difficult
to bind to.

- Nir

On Mon, Dec 16, 2019 at 1:36 PM Michael Paus  wrote:

> I don't think there are clearly right or wrong answers to all these
> questions,
> so I would just like to provide a view thoughts on this.
>
> The governing principle should be a principle of "least surprise" from a
> users
> point of view. That means we should not make things more complicated as
> they already are and should always keep the practical use-cases in mind.
> If you need full flexibility, you can always use the explicit transforms.
>
> We currently have the notion of the "Node's center" which is used for
> scaling
> and rotation and I think we should stick to that. The documentation later
> explains that "The pivot point about which the rotation occurs is the
> center
> of the untransformed layoutBounds." which is a completely arbitrary
> decision
> because, e.g., from a mathematically point of view the geometric center
> of the
> node would seem to be more natural but is more difficult to compute for
> general
> shapes. So, we should just extend this scheme in such a way that the
> user can
> replace the single computed center with a single user-defined center
> specified in untransformed coordinates. Introducing two separate centers
> for rotation and scaling is, to my opinion, just academic without any
> practical
> use-case and in the end much more complicated for the user.
>
> I would also specify this center point as a Point3D for two reasons:
> 1. Three doubles always use their full space even if you don't need them.
> 2. Using Double.NaNs as a switch between computed and user-provided center
>  is just confusing and error-prone.
>  What would be the meaning of setting x to some value but leaving y
> and z as
>  NaN? Would you implicitly set them to 0.0 or use the computed values
> or
>  would you discard this user setting completely and use all the
> computed
>  values if any of the components is NaN? I bet most users will
> forget to set the
>  Z-value anyway if they are thinking 2D. A simple null value is much
> easier
>  to handle and explain.
>
> Just my two €ent.
>
> --Michael
>
> Am 16.12.19 um 03:06 schrieb Nir Lisker:
> > Replying on the mailing list to the questions raised on GitHub.
> >
> > The state of whether to use the computed center pivot or the value of the
> >> pivot attribute is implicit with no way for an application to know
> which it
> >> is, and no way to set it back to using the computed center (i.e., the
> state
> >> is sticky once you set it). Perhaps if you defined a null value as
> meaning
> >> "computed center" then an app could at least reset it to the "computed
> >> center" state, although there would still be no way for the app to know
> >> that it was in that state.
> >>
> > In the JBS issue  I
> > alluded to this in point 5. I think that null should represent the
> default
> > (node center). However, if we use 3 doubles instead of a Point3D we 

Re: [openjdk/jfx] 8234712: Add pivot properties for scale and rotation in Node, ScaleTransition and RotateTransition (#53)

[Michael Paus]

I don't think there are clearly right or wrong answers to all these 
questions,

so I would just like to provide a view thoughts on this.

The governing principle should be a principle of "least surprise" from a 
users

point of view. That means we should not make things more complicated as
they already are and should always keep the practical use-cases in mind.
If you need full flexibility, you can always use the explicit transforms.

We currently have the notion of the "Node's center" which is used for 
scaling

and rotation and I think we should stick to that. The documentation later
explains that "The pivot point about which the rotation occurs is the center
of the untransformed layoutBounds." which is a completely arbitrary decision
because, e.g., from a mathematically point of view the geometric center 
of the
node would seem to be more natural but is more difficult to compute for 
general
shapes. So, we should just extend this scheme in such a way that the 
user can

replace the single computed center with a single user-defined center
specified in untransformed coordinates. Introducing two separate centers
for rotation and scaling is, to my opinion, just academic without any 
practical

use-case and in the end much more complicated for the user.

I would also specify this center point as a Point3D for two reasons:
1. Three doubles always use their full space even if you don't need them.
2. Using Double.NaNs as a switch between computed and user-provided center
    is just confusing and error-prone.
    What would be the meaning of setting x to some value but leaving y 
and z as

    NaN? Would you implicitly set them to 0.0 or use the computed values or
    would you discard this user setting completely and use all the 
computed
    values if any of the components is NaN? I bet most users will 
forget to set the
    Z-value anyway if they are thinking 2D. A simple null value is much 
easier

    to handle and explain.

Just my two €ent.

--Michael

Am 16.12.19 um 03:06 schrieb Nir Lisker:

Replying on the mailing list to the questions raised on GitHub.

The state of whether to use the computed center pivot or the value of the

pivot attribute is implicit with no way for an application to know which it
is, and no way to set it back to using the computed center (i.e., the state
is sticky once you set it). Perhaps if you defined a null value as meaning
"computed center" then an app could at least reset it to the "computed
center" state, although there would still be no way for the app to know
that it was in that state.


In the JBS issue  I
alluded to this in point 5. I think that null should represent the default
(node center). However, if we use 3 doubles instead of a Point3D we might
need to use Double.NaN for this instead, which would also be the default
for this case. The docs will explain this.

Do we need separate properties for scale pivot and center pivot?
I say yes, otherwise the enhancement will be very limited. I think of this
enhancement as adding pivot control to Rotate/Scale transitions, and adding
them to Node is a necessary (and desirable) step.

... you need to worry about what coordinate space the rotation pivot is

defined in. Perhaps if the rotation pivot were defined in unscaled space,
it might work.


Isn't it already? If I set the rotation pivot to the edge of the node, then
scale it down, then rotate, the rotation pivot would be outside of the
node's boundaries. In scaled space it would still be on the edge. Or did I
misunderstand you? In any case, I don't think that there's a single correct
answer here.

Should the pivot be specified as a Point3D or 3 separate doubles? Separate

doubles... there would be no out-of-band null value to use


See my point above about Double.NaN.
The doubles vs Point3D is an important choice. We might want to look into
the future even where Point3D (and 2D) could be made into an Inline class
with Valhalla, which will help with the performance aspect. Binding to one
of the coordinates is sill a problem there, however.

On Sat, Dec 14, 2019 at 6:25 PM Kevin Rushforth 
wrote:


This will need discussion on the openjfx-dev mailing list. Here are the
questions that need to be resolved:

1.

The state of whether to use the computed center pivot or the value of
the pivot attribute is implicit with no way for an application to know
which it is, and no way to set it back to using the computed center (i.e.,
the state is sticky once you set it). Perhaps if you defined a null value
as meaning "computed center" then an app could at least reset it to the
"computed center" state, although there would still be no way for the app
to know that it was in that state.
2.

Do we need separate properties for scale pivot and center pivot? A
single pivot property would be easier to define, but wouldn't allow you to
set it from a RotationTransition and a ScaleTransition if 

Re: [openjdk/jfx] 8234712: Add pivot properties for scale and rotation in Node, ScaleTransition and RotateTransition (#53)

[Nir Lisker]

Replying on the mailing list to the questions raised on GitHub.

The state of whether to use the computed center pivot or the value of the
> pivot attribute is implicit with no way for an application to know which it
> is, and no way to set it back to using the computed center (i.e., the state
> is sticky once you set it). Perhaps if you defined a null value as meaning
> "computed center" then an app could at least reset it to the "computed
> center" state, although there would still be no way for the app to know
> that it was in that state.
>

In the JBS issue  I
alluded to this in point 5. I think that null should represent the default
(node center). However, if we use 3 doubles instead of a Point3D we might
need to use Double.NaN for this instead, which would also be the default
for this case. The docs will explain this.

Do we need separate properties for scale pivot and center pivot?
>

I say yes, otherwise the enhancement will be very limited. I think of this
enhancement as adding pivot control to Rotate/Scale transitions, and adding
them to Node is a necessary (and desirable) step.

   ... you need to worry about what coordinate space the rotation pivot is
> defined in. Perhaps if the rotation pivot were defined in unscaled space,
> it might work.
>

Isn't it already? If I set the rotation pivot to the edge of the node, then
scale it down, then rotate, the rotation pivot would be outside of the
node's boundaries. In scaled space it would still be on the edge. Or did I
misunderstand you? In any case, I don't think that there's a single correct
answer here.

Should the pivot be specified as a Point3D or 3 separate doubles? Separate
> doubles... there would be no out-of-band null value to use


See my point above about Double.NaN.
The doubles vs Point3D is an important choice. We might want to look into
the future even where Point3D (and 2D) could be made into an Inline class
with Valhalla, which will help with the performance aspect. Binding to one
of the coordinates is sill a problem there, however.

On Sat, Dec 14, 2019 at 6:25 PM Kevin Rushforth 
wrote:

> This will need discussion on the openjfx-dev mailing list. Here are the
> questions that need to be resolved:
>
>1.
>
>The state of whether to use the computed center pivot or the value of
>the pivot attribute is implicit with no way for an application to know
>which it is, and no way to set it back to using the computed center (i.e.,
>the state is sticky once you set it). Perhaps if you defined a null value
>as meaning "computed center" then an app could at least reset it to the
>"computed center" state, although there would still be no way for the app
>to know that it was in that state.
>2.
>
>Do we need separate properties for scale pivot and center pivot? A
>single pivot property would be easier to define, but wouldn't allow you to
>set it from a RotationTransition and a ScaleTransition if you wanted
>to apply both to the same Node. With two separate properties, as you
>have defined it, it is more flexible, but you need to worry about what
>coordinate space the rotation pivot is defined in. The current transform
>chain looks like this:
>
> T(layout+translate) * T(pivot) * T(rot) * T(scale) * T(-pivot)
> * transform[0] * transform [1] ...
>
> Perhaps if the rotation pivot were defined in unscaled space, it might
> work. The transform chain would then look like this:
>
> T(layout+translate) * T(pivotRot/scale) * T(rot) * T(-pivotRot/scale) * 
> T(pivotScale) * T(scale) * T(-pivotScale)
> * transform[0] * transform [1] ...
>
> In any case, you need to think about the implications of having one of
> scale or rotate being set explicitly and the other being the computed
> center.
>
>1. Should the pivot be specified as a Point3D or 3 separate doubles? I
>can see pros / cons of either approach. Separate doubles are more
>consistent with the the pivot values in the Rotate and Scale Transform
>objects, and are easier to using in binding. On the other hand, there would
>be no out-of-band null value to use (see issue 1 above), so you would
>need a boolean property for each of scale pivot and rotation pivot to
>indicate whether the computed value or the value of the pivot properties
>should be used. I don't think that the fact that the rotation axis is
>defined as a Point3D should have any bearing on whether the pivot
>should be so defined. I'd probably lean towards separate doubles.
>
> —
> You are receiving this because you authored the thread.
> Reply to this email directly, view it on GitHub
> ,
> or unsubscribe
>