Processing: Creative Coding and Computational Art

door.drawDoor(x+w/2-door.w/2, y+h-door.h);
break;
case 1:
door.drawDoor(x+w/8, y+h-door.h);
break;
case 2:
door.drawDoor(x+w-w/8-door.w, y+h-door.h);
break;
}
// draw windows
int windowMargin = (w-window.w*2)/3;
window.drawWindow(x+windowMargin, y+h/6);
window.drawWindow(x+windowMargin*2+window.w, y+h/6);
// draw roof
roof.drawRoof(x, y, w, h);
}
// catch drawHouse method without boolean argument
void drawHouse(int x, int y){
// recall with required 3rd argument
drawHouse(x, y, false);
}
}
The House class is implemented similarly to the Door, Window, and Roof classes. It contains
a constructor; it has x, y, w, and h instance variables; and it has some constants and a
drawHouse() method. Again, the redundant elements and structures in these classes could
be handled more efficiently using inheritance, which I covered in Chapter 8 and will also
use in later chapters. What’s markedly different between these classes, however, is the
compositional relationship between the House class and its component classes. The House
class contains reference variables of the Door, Window, and Roof classes. When I instantiate
the House class, I’ll include Door, Window, and Roof objects as arguments that will be sent
to the House constructor.
Within the House constructor, the Door, Window, and Roof instance properties declared at
the top of the House class will each be assigned the values (object references) of their
matching parameters. Remember, the parameters declared within the constructor head
(between the parentheses) are local to the constructor, so it’s necessary to do these
assignments in the constructor to create global visibility for these passed-in values so that
they may be seen throughout the class. Because the House class will now contain object
references to these component classes (Door, Window, and Roof), the properties and methods
of each of these classes can be utilized from within the House class with the normal
syntax object.property (e.g., roof1.x) or object.method (e.g., window1.drawWindow()).
Without the object references being passed into the House constructor, the House class
would have no way of communicating with its Door, Window, or Roof components.
SHAPES
393
9