Polyline geometry

[bagnell]

Adds PolylineGeometry which creates polylines like those of PolylineCollection.
Adds PolylineColorAppearance like PerInstanceColorAppearance but for polylines.
Adds PolylineMaterialAppearance.

[pjcozzi]

Sounds cool. Update the tutorial.

[pjcozzi]

Since polyline performance is such a hot topic, once we merge this, it is worth emailing the forum to tell folks to use this for fast static polylines, and that fast dynamic polylines are a little ways out, and to watch #932 for updates.

[pjcozzi]

In the Sandcastle example, is this Mac only?

[pjcozzi]

This is a breaking change, but I suppose no need to add the noise to CHANGES.md since it is very unlikely that other folks are using this.

[pjcozzi]

Since polyline performance is such a hot topic, once we merge this, it is worth emailing the forum to tell folks to use this for fast static polylines, and that fast dynamic polylines are a little ways out, and to watch #932 for updates.

This also allows for the highly sought-after per-vertex color. It would be good to show how to do this and perhaps build it directly into PolylineGeometry. We'd need to add color to VertexFormat, which I am OK with. It should just work with PolylineColorAppearance.

[pjcozzi]

This is a trivial case, but I would still use createShaderSource to keep the shader pipeline consistent. CC @gbeatty

[pjcozzi]

Drop the parentheses.

[pjcozzi]

This looks pretty good. All the tests pass on Chrome and Firefox.

One final comment - how does a user interop between the outline geometries and the polyline geometry? Let's make it easy to construct a polyline geometry from an outline geometry, and add an example to Sandcastle.

[bagnell]

@pjcozzi This is ready for another review.

For the screen shot you posted, I think that is just the polyline disappearing over the horizon.

For your comment about using polylines as outlines, I'll do that in a separate pull request. The outlines for extruded geometry may look strange.

[pjcozzi]

For your comment about using polylines as outlines, I'll do that in a separate pull request. The outlines for extruded geometry may look strange.

OK, let's have a look then we'll make the call. It should be trivial to code.

For the screen shot you posted, I think that is just the polyline disappearing over the horizon.

Err, OK, but it looks much different in Firefox and Chrome.

[pjcozzi]

We should add this to all the Cartesian types and to CHANGES.md. Sorry, I guess I wasn't clear enough. An @example would be good to.

All this is pretty standard every time I add something to these types.

[shunter]

At first glance, this function looks identical to the pack function that @mramato already added.

[pjcozzi]

We'll take either, but it looks like unpack is duplicate with the previously existing fromArray (we misnamed writeElements to not mirror this). I'll let you guys sort out what is what, but it would be nice to stay with the from convention.

[mramato]

Keep in mind that the Packable and PackableForInterpolation interfaces are implemented by many different Core types. I'm fine with tweaking names, but we need to make sure things stay consistent for all types and that the names in the Packable interface make sense in relation to each other. I personally would just leave the Packable stuff as is and if we want to add a fromArray that just calls unpack I'm fine with that too. writeElements can just go away.

[pjcozzi]

Tests and Sandcastle example are good. This is ready pending those trivial comments.

[bagnell]

@pjcozzi This is ready for another review.

[pjcozzi]

Looks good. Merging. Also, as I said before:

Since polyline performance is such a hot topic, once we merge this, it is worth emailing the forum to tell folks to use this for fast static polylines, and that fast dynamic polylines are a little ways out, and to watch #932 for updates.

Sounds cool. Update the tutorial.

CC @hpinkos