ESP performance without WebGL

[jessegreenberg]

A number of issues in ESP will depend on whether or not we get stop using WebGL in that sim. For instance, how much work it will take to add animating text readouts will depend on whether or not WebGL can be removed (phetsims/energy-skate-park#47). A big part of that decision is to determine the performance impact of removing WebGL.

@KatieWoe could you please compare the performance without WebGL:
https://phet-dev.colorado.edu/html/energy-skate-park/1.0.0-dev.1/phet/energy-skate-park_en_phet.html?webgl=false

to the performance of the deployed sim which uses WebGL when available https://phet.colorado.edu/sims/html/energy-skate-park-basics/latest/energy-skate-park-basics_en.html

There is talk of no longer supporting iPad2, so we mostly care about the impact on Chromebooks, Edge, tablets, and the slowest platforms.

@ariel-phet can you please prioritize this request? I know that QA has a lot to work on right now, I do not feel this has to be done right away.

[samreid]

I tested https://phet-dev.colorado.edu/html/energy-skate-park/1.0.0-dev.1/phet/energy-skate-park_en_phet.html?webgl=false on iPad Air 2 running iOS 11 and the problem where the the performance drops if an svg element is (partially) offscreen is significant. Using ?profiler and turning on all checkboxes, I see 60fps when dragging the skater in the center of the play area, but it drops to 30fps when part is off the top of the screen. A consistent 30fps may be reasonable (though not desirable), but the main problem is when the frame rate jumps from 30fps to 60fps and the skater speeds up drastically.

Perhaps reopening investigation into phetsims/scenery#270 would be valuable.

Also, please note in phetsims/wave-interference#322 we identified that iOS canvas.drawImage performance changed radically from iOS 11 to iOS 12, so testing on iOS 12 (and other devices indicated in the preceding comment) will still be worthwhile.

Also, ?rootRenderer=canvas (on the same platform) gets around 16fps--pretty laggy.

[KatieWoe]

	Link One Subjective (Without WebGL)	Link One Data	Link Two Subjective (With WebGL)	Link Two Data
Edge	Pretty ok	54, normally 60	Very slow, especially when dropped or on ramp	13-21 depends on screen
Internet Explorer	good	47-60, normally in 50s	Good, not quite as, but mostly	43-60 depends on screen
Chromebook	Not bad	High 50s	Not bad	Mid to high 50s
iOS 10	ok but slow with things checked/moving things	Anywhere from 20s to 50	ok but slow when moving things	low 30s to mid 40s, sometimes dropped into 20s
iOS 11	Ok, poor when reference height changes	27 when moving reference height, high 50s otherwise	ok	High 50s/60
Mac 10.10 safari	Seems fine	45-50	Seems fine	55-60

[KatieWoe]

QA is done. @jessegreenberg let me know if you have any questions.

[jessegreenberg]

Thanks @KatieWoe, I summarized in phetsims/energy-skate-park#42 and we will continue there.

I tested the sim in iPad Air 2 iOS 12 as well and the sim is fast with and without WebGL, but does suffer from the issue that @samreid mentioned

I see 60fps when dragging the skater in the center of the play area, but it drops to 30fps when part is off the top of the screen