ExtrudeGeometry: Remove option "frames"

[Mugen87]

I'd like to suggest another simplification of ExtrudeGeometry: The removal of options.frames or the possibility to apply custom Frenet–Serret frames to the constructor.

Analogous to TubeGeometry frames are now always calculated by the given curve via Curve.computeFrenetFrames.

three.js/src/geometries/TubeGeometry.js

Line 74 in 0c6c005

var frames = path.computeFrenetFrames( tubularSegments, closed );

option.frames was never used in the examples so there is no need for modifications.

[mrdoob]

Agreed. Thanks!

[WestLangley]

Rather than removing the feature, I think it would be better to add an example demonstrating it.

What if you want to extrude a "winding yellow-brick road", and you want it to remain level so you can walk on it -- or a race track, and you want to control the embankment so you can drive on it.

The parallel transport frames implementation (#1569) does not give you that kind of control.

I recommend reverting this.

[mrdoob]

Okay. We should definitely add a example.

[Mugen87]

My long-term intention was to simplify ExtrudeGeometry a bit since its implementation feels a bit overwhelming. But I'm okay if we keep this feature and demonstrate it with an example.

Would it be okay for you to make the public methods .addShapeList(), .addShape() and .getArrays() private? 😇

[WestLangley]

I support anything you want to do to improve it. I just did not think removing the particular feature you removed was a good idea. The user does not have control over the first frame, so the 2D shape that is extruded can start out being rotated unexpectedly.

But I can see how one could argue that the feature is too complicated... and proper modeling software is a better choice.

[Mugen87]

There is another thing that bothers me. In my perfect world, we would remove all bevel related code from ExtrudeGeometry and have a BevelModifier instead. That would make the implementation of ExtrudeGeometry much more straightforward.

Unfortunately, the implementation of a generic BevelModifier is complicated. I've tried to study this topic last year but I've found almost no references. And reading the Blender source code is...well...

[WestLangley]

@Mugen87 @mrdoob After further thought, I think setting the frames is too tedious, so I now agree that the feature can be removed.

[Mugen87]

That's great. Removing frames makes it also a bit easier to serialize ExtrudeGeometry.

[mrdoob]

Should we revert the revert? 😁

[Mugen87]

I vote for yes 😁

[mrdoob]

Done!

[Mowsh]

My current project is using ExtrudeGeometry to create conveyors along arbitrary paths, the conveyors need to stay upright to match how they look and work in real life.

I feel like the frames option is the solution to a problem I've run into where at some angles my conveyors would choose strange rotations which look unrealistic. The roads that @WestLangley posted above look like exactly what is needed to make my conveyors look how I expect.

Is there a plan to replace this with equivalent functionality? Or to make ExtrudeGeometry not rotate in a way that users don't expect?

OT: @WestLangley Could you share the source code for the road image you posted above? I think this would be very useful for me.

Thanks

[WestLangley]

@Mowsh three.js is not modeling software. You really should be using modeling software, I think.

I have discovered it is very tedious specifying tangent frames; my examples above were just one-off hacks.

As an alternative, if your conveyor is flat, can you create a flat shape (like a worm) and extrude the thickness, rather than extruding the length?

[zz85]

Hmm three.js may not be intended to be a modeller's tool in general but it should be easy to build a modelling software could be built on top of three.js? eg. specifying tangent frames may be tedious but the frames can be generated by another tool in js.

but removing this isn't all bad since we don't know how often this is used, and if someone requires this option for modelling for example, the Class could easily be copied and modified