RFR: 8234920: Add SpotLight to the selection of 3D light types [v9]

[Nir Lisker]

> Added a SpotLight only to the D3D pipeline currently.
> 
> ### API discussion points
> 
> - [X]  Added `SpotLight` as a subclass of `LightBase`. However, it could also be a subclass of `PointLight` as it's a point light with direction and extra factors. I saw that `scenario.effect.light.SpotLight` extends its respective `PointLight`, but it's not a perfect analogy. In the end, I think it's a questions of whether `PointLight` will be expanded in a way which doesn't not suit `SpotLight`, and I tend to think that the answer is no.
> 
> - [X] The inner and outer angles are the "diameter angles" as shown [here](https://docs.microsoft.com/en-us/windows/win32/direct3d9/light-typeshttps://docs.microsoft.com/en-us/windows/win32/direct3d9/light-types).  I, personally, find it more intuitive that these are the "radius angles", so half these angles, as used in the spotlight factor formula. Do you think I can change this or do you prefer the current definition of the angles?
> 
> - [ ] The current implementation uses an ad-hoc direction property (using a `Point3D`). It crossed my mind that we could use the rotation transforms of the node to control the direction instead, just like we use the translation/layout of the node to get the position (there is an internal Affine3D transform for lights, not sure why `AmbientLight` needs it). Wouldn't that make more sense? When I rotate the light I would expect to see a change in direction.
> 
> ### Implementation discussion points
> 
> - [ ] I've gotten advice from a graphics engineer to treat point lights as spot lights with a 360 degrees coverage, which simplifies a few places. We can still try to optimize for a point light by looking at the light parameters: `falloff = 0` and `outerAngle = 180`. These possible optimization exist in `ES2PhongShader.java` and `D3DMeshView.cc`, and in the pixel/fragment shaders in the form of 3 different ways to compute the spotlight factor (the `computeLightN` methods). We need to check which of these give the best results.
> 
> ### Performance
> 
> Win 10
> Testing 3 point lights compared with the `master` branch shows a small drop in fps (5-10 in the mesh 200 test and ~5 in the mesh 5000 test). I repeated the tests on several occasions and got different results in terms of absolute numbers, but the relative performance difference remained more or less the same. Out of the 3 `computeSpotlightFactor` methods, `computeSpotlightFactor3`, which has no "optimizations", gives slightly better performance. The "optimizations" in `D3DMeshView.cc` didn't make a difference, which is not so surprising considering these are on the CPU.
> The sphere with 1000 subdivisions always gives 120 fps.
> 
> Ubuntu 20:
> With the patch:
> Mesh 200: 60 fps
> Mesh 5000: 15 fps
> Sphere 1000: 60 fps
> 
> Without the patch (master branch)
> Mesh 200: 60 fps
> Mesh 5000: 16.3 fps
> Sphere 1000: 60 fps
> 
> So no major changes. I will repeat these tests to make sure there was no mistake.

Nir Lisker has updated the pull request incrementally with three additional commits since the last revision:

 - Merge remote-tracking branch
 - Speculative fix for Mac
 - Fixed shader field name

-------------

Changes:
  - all: https://git.openjdk.java.net/jfx/pull/334/files
  - new: https://git.openjdk.java.net/jfx/pull/334/files/db109b28..d1bc9af5

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jfx&pr=334&range=08
 - incr: https://webrevs.openjdk.java.net/?repo=jfx&pr=334&range=07-08

  Stats: 40 lines in 4 files changed: 0 ins; 0 del; 40 mod
  Patch: https://git.openjdk.java.net/jfx/pull/334.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/334/head:pull/334

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