Is there a way to create a dotted or dashed polyline? I'm under the impression that I'd need to modify the fragment shader, but I'm not sure how to change the fragment shader via Material.shaderSource.
Currently, we do not support dot or dashed polylines, but line styles are on our Roadmap. You can try adding a stripe material where one of the colors has an alpha of 0.0 or creating the pattern yourself by ommiting points on the line.
I'll take a look at doing it with the Stripe material for now.
Using the Stripe material doesn't really have the desired effect. I need the dashes to be the same length regardless of the zoom level.