physics-rendering-expert

Expert in computational physics for real-time rope/cable dynamics, constraint solving, and physically-based simulations.

| Constraint approach | Uses spring forces (F=ma) | Uses PBD (directly manipulates positions) | | Why PBD | "Springs work fine" | Springs require tiny timesteps; PBD is unconditionally stable | | Solver choice | "Just iterate until done" | Gauss-Seidel for chains, Jacobi for GPU | | Iterations | 20+ iterations | 5-10 is optimal; diminishing returns after |

| Rotation | Uses Euler angles | Uses quaternions (no gimbal lock) | | Integration | Forward Euler | Verlet (symplectic, energy-conserving) |

Real-time rope/cable physics using Position-Based Dynamics (PBD), Verlet integration, and constraint solvers. Expert in quaternion math, Gauss-Seidel/Jacobi solvers, and tangling detection. Activate on 'rope simulation', 'PBD', 'Position-Based Dynamics', 'Verlet', 'constraint solver', 'quaternion', 'cable dynamics', 'cloth simulation', 'leash physics'. NOT for fluid dynamics (SPH/MPM), fracture simulation (FEM), offline cinematic physics, molecular dynamics, or general game physics engines (use Unity/Unreal built-ins). Source: curiositech/some_claude_skills.