[Rev 03] RFR: 8217472: Add attenuation for PointLight

[Nir Lisker]

On Wed, 5 Feb 2020 13:48:45 GMT, Kevin Rushforth <kcr at openjdk.org> wrote:

>> We have a few performance tests in apps/performance, but I don't know how up to date they are. They might give you a
>> starting point on how to measure FPS, but really the harder part is going to be coming up with a workload -- a scene
>> with a number of Shape3Ds with large triangles (so that they are fill-rate limited) and 1-3 lights, etc -- that you can
>> use to measure rendering performance without measuring overhead. Typically you want a scene that is rendering
>> continuously in the < 30 fps range, and more like 10 fps to minimize the overhead even more.  Before we figure out
>> whether we need to double the number of shaders (which was one of the ideas that I had as well), we need to know how
>> much of a problem it is. Is it < 2% performance drop on typical cases on a variety of machines or it is a 25% drop (or
>> more likely somewhere in between). If the perf drop is negligible, then it isn't worth doubling the shaders. If it is
>> significant, then we probably need to.  If we do need to double the shaders, I wouldn't do it based on the maxRange
>> being infinite, rather I would do it based on whether attenuation is being used. That way the existing shaders would be
>> unchanged, while the new shader would deal with both attenuation and the maxRange test.  Hopefully, there won't be
>> enough of a perf hit to require doubling the shaders, but we need to be able to measure it.  For functional testing, in
>> addition to the simple API tests, we want to make sure that the basic rendering is working with and without
>> attenuation. Some sort of visual test where you verify that attenuation is / isn't happening as well as testing the
>> cutoff. I wouldn't get too fancy with these...just a sanity test.
>
> Looks like the `jcheck` bot removed the `rfr` label because the CSR isn't complete. An incomplete CSR should be treated
> the same way as an insufficient number of reviewers. I filed
> [SKARA-262](https://bugs.openjdk.java.net/browse/SKARA-262) to track this.

@kevinrushforth Can you have a look at the test app? I would like to get this moving so we would have time to get the
rest of the lighting enhancements into 15.

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PR: https://git.openjdk.java.net/jfx/pull/43