#include "TimeIntegration.h"

using namespace SPH;


// ----------------------------------------------------------------------------------------------
void TimeIntegration::semiImplicitEuler(
	const Real h, 
	const Real mass, 
	Vector3r &position,
	Vector3r &velocity,
	const Vector3r &acceleration)
{				
	if (mass != 0.0)
	{
		velocity += acceleration * h;
		position += velocity * h;
	}
}

// ----------------------------------------------------------------------------------------------
void TimeIntegration::velocityUpdateFirstOrder(
	const Real h,
	const Real mass,
	const Vector3r &position,
	const Vector3r &oldPosition,
	Vector3r &velocity)
{
	if (mass != 0.0)
		velocity = (1.0 / h) * (position - oldPosition);
}

// ----------------------------------------------------------------------------------------------
void TimeIntegration::velocityUpdateSecondOrder(
	const Real h,
	const Real mass,
	const Vector3r &position,
	const Vector3r &oldPosition,
	const Vector3r &positionOfLastStep,
	Vector3r &velocity)
{
	if (mass != 0.0)
		velocity = (1.0 / h) * (1.5*position - 2.0*oldPosition + 0.5*positionOfLastStep);
}