Add note to front of repo after moving things

README.md

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+# automata_scratch
+
+This is repo has a few projects that are related in terms of
+high-level goal, but almost completely unrelated in their descent.
+
+- `python_extrude_meshgen` is some Python code from around 2019
+  September which did a sort of extrusion-based code generation.
+  While this had some good results and some good ideas, the basic
+  model was too limited in terms of the topology it could express.
+- `libfive_subdiv` is a short project around 2021 July attempting to
+  use the Python bindings of [libfive](https://www.libfive.com/), and
+  automatic differentiation in
+  [autograd](https://github.com/HIPS/autograd), to turn implicit
+  surfaces to meshes which were suitable for subdivision via something
+  like
+  [OpenSubdiv](https://graphics.pixar.com/opensubdiv/overview.html)
+  (in turn so that I could render with them without having to use
+  insane numbers of triangles or somehow hide the obvious errors in
+  the geometry).  Briefly, the process was to use edges with crease
+  weights which were set based on the curvature of the implicit
+  surface.  While I accomplished this process, it didn't fulfill the
+  goal.  Shortly thereafter, I was re-reading
+  [Massively Parallel Rendering of Complex Closed-Form Implicit Surfaces](https://www.mattkeeter.com/research/mpr/) - which, like libfive, is by Matt Keeter -
+  and found a section I'd ignored on the difficulties of producing
+  good meshes from isosurfaces for the sake of rendering.  I kept
+  the code around because I figured it would be useful to refer to
+  later, particularly for the integration with Blender.
+- `blender_scraps` contains some scraps of Python code meant to be
+  used inside of Blender's Python scripting - and it contains some
+  conversions from another project, Prosha, for procedural mesh
+  generation in Rust (itself based on learnings from
+  `python_extrude_meshgen`).  These examples were proof-of-concept of
+  generating meshes as control cages rather than as "final" meshes.