From nlisker at gmail.com  Fri Mar 15 20:18:59 2019
From: nlisker at gmail.com (Nir Lisker)
Date: Fri, 15 Mar 2019 22:18:59 +0200
Subject: Adding Scale and Rotation pivots for Node
Message-ID: <CA+0ynh8t=eYM=wvrN+t5KUjim=VPf_QbJ6RCAbGYnRx1WjRyBg@mail.gmail.com>

Hi,

I would like to implement properties for Node that control the pivots for
its built-in rotation and scaling transformations. Currently, it is
possible to do so only via a Rotate or Scale transforms, which are added to
the node's getTransforms list as both pivots are set to the Node's center.

This will make it easier to work with the built-in transforms and also
allow the scale and rotate transitions to bind to these new properties as
the next step, significantly reducing the complexity for these operations.
JBS issues have been filed in the past for this in [1] and its linked
issues.

The internal implementation changes will be in
Node#updateLocalToParentTransform() in the `if` block at line 5057 and will
include translation operations to and from the pivots. It's also possible
to separate the check for applying rotation and scaling to save on unneeded
operations, I believe.

One thing to look at carefully is the way the public API is defined. The
pivots can be represented by a Point3D or a double for each axis. Scale
transform use 3 doubles for both the scale amount and the pivot. Rotate
transform uses 3 doubles for the pivot and a Point3D for the axis. It's not
clear to me why this is the case.

As a side note, the scale and rotation built-in transforms are defined
internally in a specific order, and this order does not appear to be
documented. That is, if I setRotate(90) and setScaleX(2) I can not know
a-priori if I will scale X (scale before rotate) or Y (scale after rotate).

Comments are welcome.

- Nir

[1] https://bugs.openjdk.java.net/browse/JDK-8092304

From nlisker at gmail.com  Sun Mar 17 18:56:35 2019
From: nlisker at gmail.com (Nir Lisker)
Date: Sun, 17 Mar 2019 20:56:35 +0200
Subject: Adding Scale and Rotation pivots for Node
In-Reply-To: <CA+0ynh8t=eYM=wvrN+t5KUjim=VPf_QbJ6RCAbGYnRx1WjRyBg@mail.gmail.com>
References: <CA+0ynh8t=eYM=wvrN+t5KUjim=VPf_QbJ6RCAbGYnRx1WjRyBg@mail.gmail.com>
Message-ID: <CA+0ynh_Ok1EYmtQO6zotUO5hZ8Yyzrszc52Hy1EYBNz_rV15Xg@mail.gmail.com>

I missed that the order is defined in a few places in the docs, so ignore
my side note. There is a place or two for improving the doc that can be
taken care of in a future documentation issue for 13.

On Fri, Mar 15, 2019 at 10:18 PM Nir Lisker <nlisker at gmail.com> wrote:

> Hi,
>
> I would like to implement properties for Node that control the pivots for
> its built-in rotation and scaling transformations. Currently, it is
> possible to do so only via a Rotate or Scale transforms, which are added to
> the node's getTransforms list as both pivots are set to the Node's center.
>
> This will make it easier to work with the built-in transforms and also
> allow the scale and rotate transitions to bind to these new properties as
> the next step, significantly reducing the complexity for these operations.
> JBS issues have been filed in the past for this in [1] and its linked
> issues.
>
> The internal implementation changes will be in
> Node#updateLocalToParentTransform() in the `if` block at line 5057 and will
> include translation operations to and from the pivots. It's also possible
> to separate the check for applying rotation and scaling to save on unneeded
> operations, I believe.
>
> One thing to look at carefully is the way the public API is defined. The
> pivots can be represented by a Point3D or a double for each axis. Scale
> transform use 3 doubles for both the scale amount and the pivot. Rotate
> transform uses 3 doubles for the pivot and a Point3D for the axis. It's not
> clear to me why this is the case.
>
> As a side note, the scale and rotation built-in transforms are defined
> internally in a specific order, and this order does not appear to be
> documented. That is, if I setRotate(90) and setScaleX(2) I can not know
> a-priori if I will scale X (scale before rotate) or Y (scale after rotate).
>
> Comments are welcome.
>
> - Nir
>
> [1] https://bugs.openjdk.java.net/browse/JDK-8092304
>