import java.util.*;

/**
 * A rotation about a line.
 *
 * The line is specified by a point (x,y,z) and a unit vector (a,b,c).
 * Rotation (r) is in radians.
 */

public class Rotation extends Transformation
{
   private double m[][];

   public Rotation(double x, double y, double z,
                   double a, double b, double c,
                   double r)
   {
      double sin_r = Math.sin(r);
      double cos_r = Math.cos(r);

      double i = 1.0 - cos_r;

      double a_a_i = a * a * i;
      double b_b_i = b * b * i;
      double c_c_i = c * c * i;
      double a_b_i = a * b * i;
      double a_c_i = a * c * i;
      double b_c_i = b * c * i;

      double a_sin_r = a * sin_r;
      double b_sin_r = b * sin_r;
      double c_sin_r = c * sin_r;

      m = new double [3][3];

      m[0][0] = a_a_i + cos_r;
      m[1][0] = a_b_i - c_sin_r;
      m[2][0] = a_c_i + b_sin_r;

      m[0][1] = a_b_i + c_sin_r;
      m[1][1] = b_b_i + cos_r;
      m[2][1] = b_c_i - a_sin_r;

      m[0][2] = a_c_i - b_sin_r;
      m[1][2] = b_c_i + a_sin_r;
      m[2][2] = c_c_i + cos_r;
   }

   public void transform(Coordinates coords)
   {
      if (coords == null) return;

      double x = coords.x * m[0][0] + coords.y * m[0][1] + coords.z * m[0][2];
      double y = coords.x * m[1][0] + coords.y * m[1][1] + coords.z * m[1][2];
      double z = coords.x * m[2][0] + coords.y * m[2][1] + coords.z * m[2][2];

      coords.x = x;
      coords.y = y;
      coords.z = z;
   }
}