Expression DAG with eval, symbolic differentiation, simplification: kindred_solver/expr.py
Parameter table with fixed/free tracking: kindred_solver/params.py
Quaternion rotation as polynomial Expr trees: kindred_solver/quat.py
RigidBody entity (7 params: position + unit quaternion): kindred_solver/entities.py
Constraint residual generators (Coincident, DistancePointPoint, Fixed): kindred_solver/constraints.py
Newton-Raphson solver with symbolic Jacobian: kindred_solver/newton.py
Pre-solve passes (substitution, single-equation): kindred_solver/prepass.py
DOF counting via Jacobian rank: kindred_solver/dof.py
KCSolve IKCSolver bridge: kindred_solver/solver.py

GNN (future phases)

Graph neural network constraint prediction layer. OndselSolver C++ engine and ML training infrastructure. Moved to GNN/ — will be integrated in later phases.

Create Addon Integration

This repo is a git submodule at mods/solver/ in the Create repository. The addon loader discovers package.xml and executes Init.py, which registers the solver:

import kcsolve
from kindred_solver import KindredSolver
kcsolve.register_solver("kindred", KindredSolver)

Testing

python3 -m venv .venv && . .venv/bin/activate
pip install pytest numpy
PYTHONPATH=. pytest tests/ -v

Repository Structure

├── package.xml            # Create addon manifest
├── Init.py                # Solver registration entry point
├── kindred_solver/        # Phase 1: expression-based Newton solver
│   ├── expr.py            # Expression DAG
│   ├── params.py          # Parameter table
│   ├── quat.py            # Quaternion math as Expr trees
│   ├── entities.py        # RigidBody entity
│   ├── constraints.py     # Constraint residual generators
│   ├── newton.py          # Newton-Raphson solver
│   ├── prepass.py         # Pre-solve passes
│   ├── dof.py             # DOF counting
│   └── solver.py          # IKCSolver bridge
├── tests/                 # Unit tests (82 tests)
└── GNN/                   # GNN solver layer (future phases)

License

LGPL-2.1-or-later (see LICENSE)