Add CSGPolygon3D option to suppress end-caps

Describe the project you are working on

I'm working on the TiltFive toolkit for Godot which requires a curved pointer due to the wand design.

Describe the problem or limitation you are having in your project

I'm attempting to construct the curved pointer using a CSGPolygon3D following a bezier Path3D. The "Path Continuous U = true" and "Path U Distance = 0" options result in the path mesh having a continuous texture U coordinate from 0.0 to 1.0 across the length of the path - perfect for a shader to then shade the "active" part of the pointer.

The problem is there is no way to suppress the creation of the end-caps; and the end-caps span the complete UV coordinates:

Describe the feature / enhancement and how it helps to overcome the problem or limitation

It would be nice to add a "Suppress Endcaps" boolean property.

Describe how your proposal will work, with code, pseudo-code, mock-ups, and/or diagrams

It looks like 95% of the machinery already exists in CSGPolygon3D::_build_brush() to do this. It already suppresses the end-caps if the mode is "Spin" and the angle is 360 degrees; or if the mode is "Path" and the path is joined.

If this enhancement will not be used often, can it be worked around with a few lines of script?

There appears to be no way to suppress this, or easily delete it from the ArrayMesh after construction.

Is there a reason why this should be core and not an add-on in the asset library?

The CSGPolygon3D already does a very nice job of building swept polygons around paths, and the code is not small. Replicating it in a separate asset would mean significant duplication of code, and the corresponding maintenance issues later.

godotengine / godot-proposals