Doubling the WebGLBlock.backingScale takes too much memory

[jessegreenberg]

Found in phetsims/energy-skate-park-basics#435. WebGLBlock has these lines:

      // Double the backing scale size if we detect no built-in antialiasing.
      // See https://github.com/phetsims/circuit-construction-kit-dc/issues/139
      if ( gl.getParameter( gl.SAMPLES ) === 0 ) {
        this.backingScale *= 2;
      }

In phetsims/energy-skate-park-basics#435 it was discovered that this causes energy-skate-park-basics to crash consistently on iPad2, presumably because of extra memory usage.

@jonathanolson is there a way we could make this optional higher up, maybe in WebGLNode or something?

[jonathanolson]

I'm partially curious about whether we could investigate memory usage of the sim (and wouldn't need to make this type of change).

Alternatively, if we need to disable/change this, it would be best as a Display setting (providing a sim option in the -main.js). It would be somewhat complicated to set a flag or setting on each node that constrains the settings of WebGL blocks that it is displayed in.

I'll plan to add a Display/Sim setting to disable this for now, and later we could look into the memory usage?

[jonathanolson]

@jessegreenberg can you try providing allowBackingScaleAntialiasing: false in ESPB options, to ensure that it properly "turns off" the doubling?

[jessegreenberg]

The option works great @jonathanolson, thanks.

I'm partially curious about whether we could investigate memory usage of the sim

It would be great to do this, can you please elaborate on what you have in mind? Or maybe we could schedule a time to discuss?

[jonathanolson]

I believe we discussed memory in general, let me know if there's anything more I can do to help.

[jessegreenberg]

Thanks @jonathanolson, yes we did. And the added option is very helpful. This issue can be closed.

[jessegreenberg]

From review comment asking about this, this can now be removed since we are not using WebGL and we are no longer targeting iPad2. I tested the sim for several minutes on an iPad 3 and saw no crashing or memory related failures.

EDIT: Oops, I meant to put this in the sim issue, sorry.