Module ik 

Inverse Kinematics solvers.

Provides three complementary IK algorithms:

• FABRIK (Forward And Backward Reaching IK) – iterative, handles multi-bone chains with constraints, converges fast in ~10 iterations.
• CCD (Cyclic Coordinate Descent) – rotational approach, each joint rotates to minimize end-effector error.
• Analytical 2-bone – closed-form solution for shoulder/elbow/wrist style rigs, exact, instantaneous, with elbow pole vector control.

Quick Start

use proof_engine::animation::ik::{IkChain, FabrikSolver};
use glam::Vec3;

let mut chain = IkChain::new(vec![
    Vec3::new(0.0, 0.0, 0.0),
    Vec3::new(0.0, 1.0, 0.0),
    Vec3::new(0.0, 2.0, 0.0),
]);
FabrikSolver::solve(&mut chain, Vec3::new(1.5, 1.5, 0.0), 10);

Structs

CcdSolver

CCD: Cyclic Coordinate Descent IK.

FabrikSolver

FABRIK: Forward And Backward Reaching IK.

IkChain

A chain of joints that IK solvers operate on.

IkChain2D

2D IK chain for flat simulations (Vec2 joints).

IkJoint

A single joint in an IK chain.

IkRig

A full character IK rig with multiple named chains.

LookAtSolver

Rotates a joint to aim at a target (look-at constraint).

TwoBoneResult

Result of a 2-bone IK solve.

TwoBoneSolver

Closed-form IK for a 2-bone chain (3 joints: shoulder, elbow, wrist/hand).