RFR: 8234920: Add SpotLight to the selection of 3D light types

[Nir Lisker]

On Tue, 27 Oct 2020 23:50:08 GMT, Kevin Rushforth <kcr at openjdk.org> wrote:

>> My preference would be for `SpotLight` to subclass `PointLight`. I also somewhat prefer the 1/2 angle (radius) rather than diameter to specify the spread angles (inner and outer).
>
> Not that it's all that relevant, but I will note that the (very old) Java 3D API also had [SpotLight](https://download.java.net/media/java3d/javadoc/1.5.0/javax/media/j3d/SpotLight.html) as a subclass of [PointLight](https://download.java.net/media/java3d/javadoc/1.5.0/javax/media/j3d/PointLight.html).

Is the old implementation worth looking at, or is is completely different?

I updated the API after subclassing `PointLight`. After we settle on it I will submit a CSR and we can move on to the implementation.

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PR: https://git.openjdk.java.net/jfx/pull/334