#ifndef TRANSFORM_H
#define TRANSFORM_H

#include <cmath>
#include "lin_alg.h"

struct Transform
{
  Transform()
  {
    rot = mat_ident;
    trans = vec_zero;
  }
	matrix3d rot;
	vector3d trans;

	vector3d operator * (const vector3d & v) const
		{return rot * v + trans;}

	void Rotation(const vector3d & v, double t)
		{
			double C = cos(t);
			double S = sin(t);
			rot.a.x = C+(1-C)*v.x*v.x;
			rot.a.y = v.x*(1-C)*v.y-S*v.z;
			rot.a.z = (1-C)*v.z*v.x+S*v.y;
			rot.b.x = v.x*(1-C)*v.y+S*v.z;
			rot.b.y = v.y*v.y*(1-C)+C;
			rot.b.z = -v.x*S+v.y*(1-C)*v.z;
			rot.c.x = (1-C)*v.z*v.x-S*v.y;
			rot.c.y = v.x*S+v.y*(1-C)*v.z;
			rot.c.z = C+(1-C)*v.z*v.z;
		}

	void Translate(const vector3d & v) {trans = v;}

	void Scale(double d)
		{
			rot.a *= d;
			rot.b *= d;
			rot.c *= d;
			trans *= d;
		}

	Transform operator * (const Transform & t) const
		{
			Transform tr;
			tr.rot = rot * t.rot;
			tr.trans = rot * t.trans + trans;
			return tr;
		}

	Transform& operator = (const Transform & t)
		{
			rot = t.rot;
			trans = t.trans;
			return *this;
		}

	void MakeInverse()
		{
			rot = rot.Inverse();
			trans = rot * -trans;
		}
};

#endif