struct cpDampedSpring {
cpConstraint constraint;
cpVect anchr1;
cpVect anchr2;
cpFloat restLength;
cpFloat stiffness;
cpFloat damping;
cpDampedSpringForceFunc springForceFunc;
cpFloat target_vrn;
cpFloat v_coef;
cpVect r1;
cpVect r2;
cpFloat nMass;
cpVect n;
cpFloat jAcc;
}
@private