[Bug] Division by zero in `TripsLayer` if 2 consecutive coordinates share the same location

Description

Originally reported on Slack, but I'm moving it here for exposure:

The bug is in:

https://github.com/visgl/deck.gl/blob/e32b546539b859933be006069f3301a8e4323b1e/modules/geo-layers/src/trips-layer/trips-layer.js#L42

When 2 consecutive coordinates share the same coordinate, they’ll have vPathLength of zero, so the clipping of the line does not work and the point is colored (due to vTime being calculated from a zero division)

We use tripslayer with additive blending for light-paths and this leads to fireflies along the path.
My hotfix is vTime = instanceTimestamps + (instanceNextTimestamps - instanceTimestamps) * vPathPosition.y / ((vPathLength > 0.0) ? 1.0 : vPathLength); but there might be better ways to fix it.

This line could also probably replaced by a mix(instanceTimestamps, instanceNextTimestamps, (vPathLength > 0.0) ? (vPathPosition.y / vPathLength) : 0.5) to make it more explicit (for human reader and shader compiler alike?)

//Edit: I actually ran into precision issues with the code above. I'm now using this:

highp float pathPositionYInstancePercentage = (vPathLength > 0.0) ? (vPathPosition.y / vPathLength) : 0.5;
vTime = mix(instanceTimestamps, instanceNextTimestamps, pathPositionYInstancePercentage);

Flavors

• React
• Python/Jupyter notebook
• MapboxLayer
• GoogleMapsOverlay
• CartoLayer
• DeckLayer/DeckRenderer for ArcGIS

Expected Behavior

Do not divide by zero and provide a sane vTime

Steps to Reproduce

Create a TripsLayer with the same location repeated twice for waypoints on the path coordinates / positions.

Environment

n/a

Logs

n/a