/// <summary>
/// Uses Runge-Kutta fourth order integration
///
/// </summary>
/// <remarks>Reference: Integration Basics by Glenn Fiedler
/// http://gafferongames.com/game-physics/integration-basics/</remarks>
/// <param name="state">Physics state</param>
/// <param name="t">Time</param>
/// <param name="dt">Time derived (step)</param>
/// <param name="acceleration"></param>
public static void RK4Integrate(ref ObjectStateQuat state, float t, float dt, Func <ObjectStateQuat, float, Quaternion> acceleration)
{
StateDerivativeQuat a = EulerEvaluate(state, t, 0.0f, new StateDerivativeQuat(), acceleration);
StateDerivativeQuat b = EulerEvaluate(state, t + dt * .5f, dt * .5f, a, acceleration);
StateDerivativeQuat c = EulerEvaluate(state, t + dt * .5f, dt * .5f, b, acceleration);
StateDerivativeQuat d = EulerEvaluate(state, t + dt, dt, c, acceleration);
Quaternion dxdt = 1f / 6 * (a.Velocity + 2f * (b.Velocity + c.Velocity) + d.Velocity);
Quaternion dvdt = 1f / 6 * (a.Acceletaion + 2f * (b.Acceletaion + c.Acceletaion) + d.Acceletaion);
state.Value = state.Value + dxdt * dt;
state.Velocity = state.Velocity + dvdt * dt;
}
public static StateDerivativeQuat EulerEvaluate(ObjectStateQuat initial, float t, float dt, StateDerivativeQuat der, Func <ObjectStateQuat, float, Quaternion> acceleration)
{
ObjectStateQuat state;
state.Value = initial.Value + der.Velocity * dt;
state.Velocity = initial.Velocity + der.Acceletaion * dt;
StateDerivativeQuat output;
output.Velocity = state.Velocity;
output.Acceletaion = acceleration(state, t + dt);
return(output);
}
public static StateDerivativeQuat EulerEvaluate(ObjectStateQuat initial, float t, float dt, StateDerivativeQuat der, Func<ObjectStateQuat, float, Quaternion> acceleration)
{
ObjectStateQuat state;
state.Value = initial.Value + der.Velocity * dt;
state.Velocity = initial.Velocity + der.Acceletaion * dt;
StateDerivativeQuat output;
output.Velocity = state.Velocity;
output.Acceletaion = acceleration(state, t + dt);
return output;
}
/// <summary>
/// Uses Runge-Kutta fourth order integration
///
/// </summary>
/// <remarks>Reference: Integration Basics by Glenn Fiedler
/// http://gafferongames.com/game-physics/integration-basics/</remarks>
/// <param name="state">Physics state</param>
/// <param name="t">Time</param>
/// <param name="dt">Time derived (step)</param>
/// <param name="acceleration"></param>
public static void RK4Integrate(ref ObjectStateQuat state, float t, float dt, Func<ObjectStateQuat, float, Quaternion> acceleration)
{
StateDerivativeQuat a = EulerEvaluate(state, t, 0.0f, new StateDerivativeQuat(), acceleration);
StateDerivativeQuat b = EulerEvaluate(state, t + dt * .5f, dt * .5f, a, acceleration);
StateDerivativeQuat c = EulerEvaluate(state, t + dt * .5f, dt * .5f, b, acceleration);
StateDerivativeQuat d = EulerEvaluate(state, t + dt, dt, c, acceleration);
Quaternion dxdt = 1f / 6 * (a.Velocity + 2f * (b.Velocity + c.Velocity) + d.Velocity);
Quaternion dvdt = 1f / 6 * (a.Acceletaion + 2f * (b.Acceletaion + c.Acceletaion) + d.Acceletaion);
state.Value = state.Value + dxdt * dt;
state.Velocity = state.Velocity + dvdt * dt;
}
