Blender Grease Pencil Interpolation

This is in response to the current development going on in: developer.blender.org/D9839/new/

This is how OpenToonz did it: github.com/opentoonz/opentoonz/pull/1297 implementation and comments are insightful for how animators are using these tools and why.

In relation to drawing direction of how Grease Pencil Strokes were drawn. Blenders normals along a curve already exist. It could always be made sexier. Should do for now as a prototype though.

The only thing that I would add here is to make this a fully complete feature automating the process talked about here blender.community/c/rightclickselect/nKgbbc/

This is a great read on tweening. It would be interesting to be able to draw and sculpt the path of interpolation at both endpoints of a grease pencil stroke? cgl.ethz.ch/publications/papers/paperWhi10.php

To go one step further Blender's cloth sewing/ stitching code could potentially be utilized to help create a view of how Grease Pencil points are going to be interpolated. This may be something like: youtube.com/watch Code from the "follow path modifier" might be able to help out and do some of the heavy liftings as well.

The below example: Blue = Grease Pencil Line Red & Green = End points Orange = interpolation line. Line of action