package modeler.shape;

import javax.vecmath.Point2f;
import javax.vecmath.Point3f;
import javax.vecmath.Point3i;
import javax.vecmath.Vector3f;

/**
 * Models a cube.  The mesh for a cube is derived from static data.  The vertices
 * for each face must be replicated to avoid smoothing the corners for the cube.
 * @author ags
 */
public class Cube extends Shape {

  private static final long serialVersionUID = 3256437006337718072L;
  
  /* The eight vertices of the cube. n = negative, p = positive */
  private static final Point3f nnn = new Point3f(-1.0f, -1.0f, -1.0f);
  private static final Point3f nnp = new Point3f(-1.0f, -1.0f, +1.0f);
  private static final Point3f npn = new Point3f(-1.0f, +1.0f, -1.0f);
  private static final Point3f npp = new Point3f(-1.0f, +1.0f, +1.0f);
  private static final Point3f pnn = new Point3f(+1.0f, -1.0f, -1.0f);
  private static final Point3f pnp = new Point3f(+1.0f, -1.0f, +1.0f);
  private static final Point3f ppn = new Point3f(+1.0f, +1.0f, -1.0f);
  private static final Point3f ppp = new Point3f(+1.0f, +1.0f, +1.0f);

  /* Normals for the different faces of the cube */
  private static final Vector3f lNormal = new Vector3f(-1, 0, 0);
  private static final Vector3f rNormal = new Vector3f(+1, 0, 0);
  private static final Vector3f dNormal = new Vector3f(0, -1, 0);
  private static final Vector3f uNormal = new Vector3f(0, +1, 0);
  private static final Vector3f bNormal = new Vector3f(0, 0, -1);
  private static final Vector3f fNormal = new Vector3f(0, 0, +1);

  // Vertex matrix
  private static final Point3f[] vertices = new Point3f[] { ppp, npp, nnp, pnp, // Front face
                                                            ppn, pnn, nnn, npn, // Back face
                                                            ppn, ppp, pnp, pnn, // Right face
                                                            npp, npn, nnn, nnp, // Left face
                                                            ppp, ppn, npn, npp, // Up face
                                                            pnp, nnp, nnn, pnn }; // Down face

  // Normal matrix
  private static final Vector3f[] normals = new Vector3f[] { fNormal, fNormal, fNormal, fNormal,
                                                             bNormal, bNormal, bNormal, bNormal, 
                                                             rNormal, rNormal, rNormal, rNormal, 
                                                             lNormal, lNormal, lNormal, lNormal, 
                                                             uNormal, uNormal, uNormal, uNormal, 
                                                             dNormal, dNormal, dNormal, dNormal };

  private static final Point3i[] triangles = new Point3i[] { new Point3i(0, 1, 2),
                                                             new Point3i(2, 3, 0), 
                                                             new Point3i(4, 5, 6), 
                                                             new Point3i(6, 7, 4), 
                                                             new Point3i(8, 9, 10), 
                                                             new Point3i(10, 11, 8),
                                                             new Point3i(12, 13, 14), 
                                                             new Point3i(14, 15, 12), 
                                                             new Point3i(16, 17, 18),
                                                             new Point3i(18, 19, 16),
                                                             new Point3i(20, 21, 22), 
                                                             new Point3i(22, 23, 20) };
  
  //The static mesh for the cube
  private transient static Mesh cubeMesh;

  /**
   * Required for IO
   */
  public Cube() {}
  
  /**
   * @see modeler.shape.Shape#buildMesh()
   */
  public void buildMesh() {

    //Do nothing if the mesh has already been built
    if(cubeMesh != null) {
      mesh = cubeMesh;
      return;
    }
    
    //Build the mesh data arrays from the static mesh data
    int vertLength = vertices.length;
    float[] vertData = new float[3*vertLength];
    float[] normData = new float[3*vertLength];
    
    //Create the triangle list
    int[] triData = new int[3*triangles.length];
    
    //Copy the vertex data
    for(int i = 0; i < vertLength; i++) {
      
      vertData[3*i] = vertices[i].x;
      vertData[3*i+1] = vertices[i].y;
      vertData[3*i+2] = vertices[i].z;
      normData[3*i] = normals[i].x;
      normData[3*i+1] = normals[i].y;
      normData[3*i+2] = normals[i].z;
      
    }
    
    //Copy the triangle data
    for(int i = 0; i < triangles.length; i++) {
      
      triData[3*i] = triangles[i].x;
      triData[3*i+1] = triangles[i].y;
      triData[3*i+2] = triangles[i].z;
      
    }
    
    //Create the mesh
    cubeMesh = new Mesh(vertData, triData, normData);
    mesh = cubeMesh;
      
  }
}
