Examples: Make webgl_morphtargets_sphere FPS-independent.

[Mugen87]

Currently, the animated sphere looks very strange on a 144 Hz monitor^^.

Besides, this example should demonstrate how you can use the Page Visibility API together with THREE.Clock to avoid large delta values when the tab is switched or the browser is minimized.

At some point, we might want to replace the code with THREE.Timer. For now, I guess it gives some ideas how to solve the issue with just THREE.Clock.

[WestLangley]

this example should demonstrate how you can use the Page Visibility API together with THREE.Clock to avoid large delta values when the tab is switched or the browser is minimized.

It is helpful if two tabs remain synchronized when doing before-and-after comparisons.

Can the clock be reset (somehow) in another example to show how to maintain synchronous animations?

[Mugen87]

A modern Timer class normally uses the Performance API in order to retrieve high resolution timestamps (of type DOMHighResTimeStamp). These values are relative to the time origin which is unique per tab/window. Since it's a read only value, I'm not aware of a way to synchronize the time origin across tabs in order to get exact elapsed time values.

Even if you could share a common time origin, both tabs are rendered with different frametimes so the delta time values will be different. Meaning you can't achieve 100% synchronous animations.

[mrdoob]

Thanks!