// This function draws a mailbox. The mailbox's origin is at the center at the base 
// of the post of the mailbox. 
// The mailbox is drawn upright, sitting on the x-z plane. 
// The opening of the mailbox is along the z axis and faces down the +ve z axis.
// The user specifies the height of the mailbox as a float and 
// an integer choosing from one of 3 colors (0:red, 1:green, 2:purple)
// The default mailbox is purple.
// The mailbox's width is a third of the height specified and the depth 
// is about 2/3rds the height of the mailbox.  
// The length of the post of the mailbox is .6 of the height.
// The post of the mailbox is automatically set to brown.
void sdelrosaMailbox(float height, int color){
  // load all the textures
  GLuint textureIDs[6];
  glGenTextures(6, textureIDs);
  twLoadTexture(textureIDs[0], twPathname("mailboxRed.ppm",false));
  twLoadTexture(textureIDs[1], twPathname("mailboxGreen.ppm",false));
  twLoadTexture(textureIDs[2], twPathname("mailboxPurple.ppm",false));

  // The length of the post from the ground
  float postHeight= height*.6;
  // The height of the curve of the mailbox from the base
  float curveHeight= height-postHeight;
  // The width of the base
  float baseWidth= height/3.0;
  // The depth of the base
  float baseDepth= height*2.0/3.0;

  // Brown for the post of the mailbox
  twTriple brown= {132.0/255.0, 64.0/255.0, 40.0/255.0};
  glPushMatrix();
  glTranslatef(0,postHeight*.5, 0);
  glScalef(.25, 1, .25);         // The thickness of the post is .25 of the length
  twColor(brown, .4, 5);        // Set the color
  glutSolidCube(postHeight);      // Draw the post
  glPopMatrix();
  
  glPushMatrix();
  //Translate to top of post, back, left corner to draw base. 
  glTranslatef(-baseWidth*.5,postHeight,-baseDepth*.5);  
  
  // Control points for the curved surface (some vertices are used to draw base)
  GLfloat curve[16][3] =          
    {
      {baseWidth,0,0},                   // Points on the plane z=0         
      {baseWidth,curveHeight,0},
      {0,curveHeight,0},
      {0,0,0},                     

      {baseWidth,0,baseDepth*.3},       // Points on the plane z=baseDepth*.3         
      {baseWidth,curveHeight,baseDepth*.3},
      {0,curveHeight,baseDepth*.3},
      {0,0,baseDepth*.3},                     

      {baseWidth,0,baseDepth*.6},        // Points on the plane z=baseDepth*.6               
      {baseWidth,curveHeight,baseDepth*.6},
      {0,curveHeight,baseDepth*.6},
      {0,0,baseDepth*.6},                     

      {baseWidth,0,baseDepth},           // Points on the plane z=baseDepth            
      {baseWidth,curveHeight,baseDepth},
      {0,curveHeight,baseDepth},
      {0,0,baseDepth},                     
    };    

  glEnable(GL_CULL_FACE);     // Because we are drawing 2 sides
                              // with opposite normals
  glBegin(GL_QUADS);          // Draw the base 
  {
    glNormal3f(0,1,0);
    glVertex3fv(curve[0]); 
    glVertex3fv(curve[12]);
    glVertex3fv(curve[15]);
    glVertex3fv(curve[3]);
    glNormal3f(0,-1,0);
    glVertex3fv(curve[3]); 
    glVertex3fv(curve[15]);
    glVertex3fv(curve[12]);
    glVertex3fv(curve[0]);
  }
  glEnd();
  glDisable(GL_CULL_FACE);
    
  // Texture coordinates
  GLfloat texture[8] =            
  {
    1,1, 1,0,
    0,1, 0,0
  };    
  
  // Set the underlying color of the surface to white
  twTriple white= {1.0,1.0,1.0};
  twColor(white,.7, 100);
  glEnable(GL_TEXTURE_2D);
  
  // Choosing which color to use for the mailbox
  if(color==0){
    glBindTexture(GL_TEXTURE_2D, textureIDs[0]);
  }else if (color==1){
    glBindTexture(GL_TEXTURE_2D, textureIDs[1]);
  }else{
    glBindTexture(GL_TEXTURE_2D, textureIDs[2]);
  }

  // Draw the curved surface
  glMap2f(GL_MAP2_VERTEX_3, 0, 1, 3, 4, 0, 1, 12, 4, curve[0]);
  glMap2f(GL_MAP2_TEXTURE_COORD_2, 0, 1, 2, 2, 0, 1, 4, 2,texture);
  glEnable(GL_MAP2_VERTEX_3);
  glEnable(GL_MAP2_TEXTURE_COORD_2);
  glEnable(GL_AUTO_NORMAL);
  glMapGrid2f(10,0,1,10,0,1);
  glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
  glEnable(GL_NORMALIZE);
  glEvalMesh2(GL_FILL, 0, 10, 0, 10);
  glDisable(GL_TEXTURE_2D);
  glPopMatrix();
}