FieldNode compass needles are pixelated

[matthew-blackman]

As part of #103, @samreid and I noticed that the compass needle images comprising the FieldNode were being rendered at a lower resolution than the other compass needles throughout the sim (see screenshot below). Let's discuss if there is a way to increase their resolution so that all compass needles render at the same quality.

[pixelzoom]

The field needles are necessarily rendered differently than the compass needle, so there's always the likelihood that the rendering quality may vary, depending on what scenery renderer options are supporteed by the browser. That said...

The field (FieldNode) uses scenery Sprites. In #109, we're having problems getting the webgl renderer working, and it's currently falling back to canvas. Until that issue is resolved, I'm not going to work on this issue.

[pixelzoom]

@matthew-blackman Please provide platform issues when creating issues like this one. I need details on the OS and browser, with version number for both. Also nice to know whether it's specific to one platform, or at least whether that was checked.

[pixelzoom]

On macOS + Chrome (both latest) I can only see this pixelation if I zoom in using the pan-and-zoom feature. So I'm wondering (a) Is this how you created the screenshot above? (b) If so, how important is this?

[pixelzoom]

WebGL looks similar when zooming in with pan-and-zoom, see below. So resolving #109 is unlikely to change this. @jonathanolson please advise on how to make the B-field render more crisply.

[jonathanolson]

Added scaling and mipmapping to get a decent visual appearance throughout the possible zoom range. @pixelzoom can you check/review?

[pixelzoom]

Changes look great @jonathanolson -- screenshot below, zoomed in using pan-and-zoom feature.

Back to @matthew-blackman or @samreid for review, close if OK.

[samreid]

Everything looks great here, nice work @jonathanolson and @pixelzoom. Thanks for pointing this out @matthew-blackman. Closing.