(feat) Hobby Splines

[cuttlefisch]

Goal

Implement Hobby Splines inspired by Jake Low's post Hobby’s algorithm for aesthetic Bézier splines that "render down" to bezier curves.

Functionality

• Use hobby_point function to create a list in the form of [Knot, Control Control, Knot,... ] representing knots and controls for bezier curves defined using hobby's algorithm.
• Control whether curves are open or closed using the close_loop boolean.

The curve from the last knot point to the first is generated regardless of close_loop so that the tangents at the first and last knot point are those of the closed hobby spline; this helps keep the curves round and aesthetic. To generate the resulting hobby points the final segment of the curve is set to the closed loop curve is appended if the curve is closed, otherwise only the final point is appended.

Changes

• Add hobby_points function to splines in order to generate bezier curves following Hobby's algorithm.
• Add new example file hobby_splines_example.py with open & closed hobby splines & their polygon projections
• Add tests for hobby_points to test_splines.py for open hobby splines using bezier_controls in raw, Point2, and Point3 forms

Examples

Create hobby curve examples by running hobby_splines_example.py.

Testing

Test changes using test_splines.py.