Sun Size

[bagnell]

Fixes #769. Doesn't turn the sun glow off but the size is correct.

[mramato]

I believe you if you say it's right now, but this looks ridiculously small.

[pjcozzi]

The code is fine. JSHint and tests pass.

I agree that this looks lame compared to before. STK makes the sun look much bigger by adding a large glow, and Google Earth has a huge sun.

There are several directions to improve this, e.g., do something similar to STK, scale up the sun by default with an option to change it, etc. Do what you think is best.

Also, when we redo the atmosphere (soonish), the sun may come for free for ground views, but that doesn't help us here.

[emackey]

I'm still experimenting with this, maybe I can get a better look for it.

[pjcozzi]

@emackey any update?

[emackey]

Not yet, sorry, other projects calling me. Soon.

[emackey]

I just showed Dan that the Sun's size with setGlowFactor(0) is still about 10% larger than seen in STK at the same FOV. He's looking into it.

[bagnell]

@emackey I changed the way the sun is sized again. You said you developed a few new ways to test it. Could you run through them. (The glow is temporarily broken).

[emackey]

The new sun size is an exact match to STK, perfect! For those following along, my testing methods are:

1. In STK, use 3D window properties to set a large square 3D window (800 x 800, for example, square so that FOV is the same horizontally as vertically). In Globe Manager, turn off Sun->Sunshine, but make sure the Sun's globe is turned on. In advanced properties, set min visible distance to 1e9 km. Zoom out from the Earth, find the Sun, and crank down FOV to 1 degree so the Sun fills more than half the window. Take a screenshot of this into a paint program. Then set up the same scene at the same window size in Cesium, glowFactor zero, and paste that screenshot as a new layer, setting the opacity to about half. Then move the top layer until the Sun lines up with the bottom layer. It's pixel-perfect.

2. Alternate method, find the distance from the Earth where the Sun has the same apparent size as the Earth. Less accurate, but not prone to FOV differences between rendering environments. STK shows the answer is roughly 1.38e6 km, and Cesium now agrees with this.

[emackey]

I think all of my review comments from @mramato are addressed now. I know @bagnell is still planning to fix the glow size. Also, master needs to merge in, then we're ready.

[bagnell]

@emackey Can you check this once more? I fixed the glow and checked using your first method. With the glow its a little bigger, but that is expected because of the bloom filter.

@pjcozzi This is ready for a review.

[emackey]

I tweaked the strength of the "burst" and recalibrated the default to 1.0. Size is still correct. This is ready for master.

[emackey]

Just found an odd visual artifact. On my widescreen monitor, with Chrome maximized, the Sun is larger out near the edge. This is perhaps expected due to perspective, but in this case there's a specific "jump" in size as the sun moves in and out of the zone. Could be blooming turning on and off, maybe.

[bagnell]

This is ready. The size is right wherever it is on the screen and there is a property that can enable/disable bloom.

[pjcozzi]

It's cleaner to keep this as a boolean, i.e., false. I suspect we do that elsewhere.

[pjcozzi]

Tests and examples look good. This is ready pending my minor comments and an update to CHANGES.md.

[bagnell]

@pjcozzi This is ready for another review.

[pjcozzi]

Looks good.