Potential chart affected by zooming during neuron stimulation

[elisemorgan]

Test device: iPad 3, Disessa

Operating System: iOS 9.2 13C75

Browser: Safari

Problem description: The potential plot is sharper if the zoom is changed while the neuron is stimulated. In the screenshot below, the first peak is with zoom and the second peak is normal.

Steps to reproduce: Select potential chart. Stimulate neuron and zoom in and out during stimulation.

Severity:

Screenshots:

Troubleshooting information (do not edit): Name: ‪Neuron‬ URL: http://www.colorado.edu/physics/phet/dev/html/neuron/1.0.0-rc.1/neuron_en.html Version: 1.0.0-rc.1 2015-12-22 23:06:19 UTC Features missing: fullscreen Flags: pixelRatioScaling User Agent: Mozilla/5.0 (iPad; CPU OS 9_2 like Mac OS X) AppleWebKit/601.1.46 (KHTML, like Gecko) Version/9.0 Mobile/13C75 Safari/601.1 Language: en-us Window: 1024x672 Pixel Ratio: 2/1 WebGL: WebGL 1.0 (OpenGL ES 2.0 IMGSGX543-124.1) GLSL: WebGL GLSL ES 1.0 (OpenGL ES GLSL ES 1.00) Vendor: WebKit (WebKit WebGL) Vertex: attribs: 16 varying: 8 uniform: 128 Texture: size: 4096 imageUnits: 8 (vertex: 8, combined: 8) Max viewport: 4096x4096 OES_texture_float: true Dependencies JSON: {"assert":{"sha":"d4909677","branch":"HEAD"},"axon":{"sha":"6f3c2e01","branch":"HEAD"},"babel":{"sha":"9618fad2","branch":"master"},"brand":{"sha":"c9282935","branch":"HEAD"},"chipper":{"sha":"1d1d5d32","branch":"HEAD"},"dot":{"sha":"7a28b1a9","branch":"HEAD"},"griddle":{"sha":"3adb78bd","branch":"HEAD"},"joist":{"sha":"191b15a4","branch":"HEAD"},"kite":{"sha":"4a947119","branch":"HEAD"},"neuron":{"sha":"3b7eee9d","branch":"HEAD"},"phet-core":{"sha":"73a034c6","branch":"HEAD"},"phetcommon":{"sha":"d712ace0","branch":"HEAD"},"scenery":{"sha":"47143cdd","branch":"HEAD"},"scenery-phet":{"sha":"a7f975d1","branch":"HEAD"},"sherpa":{"sha":"be8c4fc9","branch":"HEAD"},"sun":{"sha":"64555735","branch":"HEAD"},"tandem":{"sha":"07fbe58c","branch":"HEAD"}}

[elisemorgan]

Not reproducible on iPad 2 w/ iOS 9

[arouinfar]

Also not reproducible on the latest desktop version of Safari.

[jbphet]

Also not reproducible on Win7 + Chrome, Win7 + Firefix, or Win7 + IE11.

Assigning to @elisemorgan to see if she can reproduce on any other devices besides iPad 3.

[amanda-phet]

I could not reproduce on OSX 10.10 Safari.

[amyh-phet]

Not reproducible on Chromebook either.

[elisemorgan]

@jbphet This issue appears on iPad 2 8.4

[arouinfar]

I noticed this issue on Tycho too -- iPad2 running iOS 9.2.

[arouinfar]

I just saw @elisemorgan's comment that she couldn't reproduce on iPad2/iOS9. The deformity in the graph is not as noticeable as the screenshots in the original post.

The first bump in the graph in the first screenshot below has the correct shape. There's a little kink around 2ms. The following three times I stimulated the neuron, I wiggled the zoom back and forth while the bump was being drawn. In all three cases, the graph is a bit deformed. The lack of the initial kink is the most noticeable difference (particularly in the first bump on the 2nd graph).

[jbphet]

I spent some time looking at this, and it is due to the sim trying to keep up while simultaneously working to re-scale everything in the view window. There is no easy fix. Some of the recent changes seem to help such that the very spiky graph that @elisemorgan was able to create is difficult if not impossible to reproduce, but some loss of fidelity is still occurring when this test is run on the latest RC (1.0.0-rc.2). This is a rare and kind of abusive use case, and in my opinion this issue should not block publication. Assigning to @ariel-phet to disposition.

[ariel-phet]

Does not occur with regular zooming in and out. Closing

[jbphet]

A related issue (see #114) has pushed this over the threshold to the point where I will likely add some code to address it, at least partially. Reopening.

[jbphet]

After more investigation, I realized that having the sim in fast forward mode is vital to reproducing this issue. While doing that, I was able to reproduce the problem on an iPad 2 running iOS 9.2.1 (the PhET test device named "Witten"). Screenshot:

I added code to break large simulation time ticks into multiple smaller ticks and re-ran the test. The resulting graph is much improved. Screenshot:

[elisemorgan]

@jbphet On iPad 3, I am now seeing the same thing as @arouinfar has in her screenshots above. There is only the minor kink at the very beginning. I'm thinking that the issue is resolved.

[ariel-phet]

Agreed, resolved, closing