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

[Kevin Rushforth]

On Wed, 11 Mar 2020 21:35:55 GMT, Kevin Rushforth <kcr at openjdk.org> wrote:

>> I'll take a look. My quick thought is that we need some sort of test with a reasonable number of large boxes (so that
>> it is fill-limited). If there isn't such a case, and the 3D rendering is always node-limited, then the shader
>> performance doesn't really matter all that much. I suspect we should be able to find a case where it does, but we'll
>> see.
>
> I did some limited testing today with a modification to the test program you attached to create a MeshView with 200
> large quads (400 triangles) in a single node. This will eliminate the node overhead. I can confirm that it is fill rate
> limited, because when I send the exact same amount of data, but make the triangles small, the frame rate goes up as
> expected.  It sill looks like it isn't shader limited, though, at least on my Windows 10 machine, which has an Intel
> UHD Graphics 630. More testing is needed on other platforms. I'll share the mods to the test program when I have time,
> but it's basically just creating a set of quads on top of each other by reusing the same 4 points in each pair of faces.

I'll attach the above modified testcase that I ran. I ran it on a relatively new Windows 10 laptop and a rather ancient
MacBook Pro. I had to drastically reduce the number of quads on the Mac, but the results are similar: no significant
difference between the current code and the proposed patch for point lights (without attenuation).

I'd like to see results on a recent machine with a graphics accelerator (either NVIDIA or AMD/ATI) to see if the new
shader hurts performance there, but I suspect it will be fine.

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