RFR: 8234920: Add SpotLight to the selection of 3D light types [v13]

[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
> 
> Testing 3 point lights and comparing this branch with `master` using a 1000 division sphere, 200 meshes, and 5000 meshes.
> Using an AMD RX 470 4GB GPU.
> 
> In this branch, there is a possible CPU optimization for checking the light type and using precalculated values (in `D3DMeshView.cc` for d3d and `ES2PhongShader.java` for opengl). On the GPU, I tried 3 ways of computing the spotlight factor contributions (`computeSpotlightFactor`, `computeSpotlightFactor2` and `computeSpotlightFactor3`) trying out different branching and shortcuts.
> 
> ### Results
> The CPU "optimizations" made no difference, which is understandable considering it will not be the bottleneck. We can remove these if we want to simplify, though maybe if we allow a large number of lights it could make a difference (I doubt it). I don't have a strong preference either way.
> 
> The sphere 1000 tests always gave max fps (120 on Win and 60 on Ubuntu).
> 
> **Win 10**
> Compared with the `master` branch, this patch shows 5-10 fps drop 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.
> 
> **Ubuntu 18**
> The mesh 200 test always gave 60 fps because it is locked to this fps, so we can't measure the real GPU performance change.
> The mesh 5000 test shows 2-6 fps drop from master, with `computeSpotlightFactor` > `computeSpotlightFactor2`  > `computeSpotlightFactor3` at in terms of performance (~2 fps difference each).
> 
> **Conclusion**: we can expect a 5 fps drop more or less with 3 point lights. `computeSpotlightFactor3` on d3d and `computeSpotlightFactor` on opengl gave the best performances.

Nir Lisker has updated the pull request incrementally with one additional commit since the last revision:

  Corrected light direction in the es2 pipeline

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

Changes:
  - all: https://git.openjdk.java.net/jfx/pull/334/files
  - new: https://git.openjdk.java.net/jfx/pull/334/files/ce075b22..7c36639e

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jfx&pr=334&range=12
 - incr: https://webrevs.openjdk.java.net/?repo=jfx&pr=334&range=11-12

  Stats: 13 lines in 3 files changed: 0 ins; 0 del; 13 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