289 - Rotation Matrix Z

//
//  RotationMatrixZ.java
//  Easel
//
//  Created by Philip Rhodes on 7/29/05.
//  Copyright 2005 __MyCompanyName__. All rights reserved.
//

/** This class represents matrices that rotate vertices around the z axis.
  * according to the "right hand rule".
  */
public class RotationMatrixZ extends RotationMatrix{

   /** Constructs a rotation matrix with rotation angle 0. */
   public RotationMatrixZ(){
      // The default constructor will set this matrix
      // equal to the identity, so do nothing here.
   }

   /** Construct a matrix that will rotate vertices around the z axis by the
    *  angle theta, expressed in radians."
    */
   RotationMatrixZ(double theta){
     // Write me!
      float  [][] rotationx_matrix =
              {{(float)Math.cos(theta),  -(float)Math.sin(theta),    0.0f,                    0.0f},
              {(float)Math.sin(theta),    (float)Math.cos(theta),    0.0f,                    0.0f},
              {0.0f,                      0.0f,                      1.0f,                    0.0f},
              {0.0f,                      0.0f,                      0.0f,                    1.0f}
      };

      matrix = rotationx_matrix;
   }

   /** Set the angle of rotation to theta, expressed in radians.  */
   public void setAngle(double theta){
      // Write me!
      matrix[0][0] = (float)Math.cos(theta);
      matrix[0][1] = -(float)Math.sin(theta);
      matrix[1][0] = (float)Math.sin(theta);
      matrix[1][1] = (float)Math.cos(theta);
   }
}