RFR: 8234920: Add SpotLight to the selection of 3D light types [v20]

[Kevin Rushforth]

On Sun, 6 Jun 2021 17:23:45 GMT, Nir Lisker <nlisker at openjdk.org> wrote:

>> modules/javafx.graphics/src/main/java/javafx/scene/SpotLight.java line 144:
>> 
>>> 142:     /**
>>> 143:      * The angle of the spotlight's inner cone, in degrees (as shown in the class doc image). A point whose angle to the
>>> 144:      * light's position is less than this angle is not attenuated by the spotlight factor ({@code spot = 1}). At larger
>> 
>> The term `angle to the light position` isn't precise since you need a second vector to form an angle. In the class docs, you use the wording `point whose vector to the light position forms an angle {@code theta} with the direction of the light`, which I like. Maybe you could work that into this description somehow?
>
> It can become cumbersome. Something like `A point whose whose vector to the light's position and the direction of the light form an angle that is less than this angle is not attenuated by the spotlight factor`  or `A point whose vector to the light's position forms an angle {@code theta} with the direction of the light, and {@code theta} is smaller than this angle, is not attenuated by the spotlight factor.` is a lot to digest.
> 
> I think that the meaning is intuitive. Maybe I can defined what an "angle of a point to the light" is in the class doc and use that definition in the `innerAngle` and `outerAngle` docs.

Yeah, I see your point. And yes, I think it would help to define that term in the class docs.

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