Recursion - Java Software Solutions: Foundations of Program Design - page 609

LISTING 12.7 continued

// intermediate points are computed, and each line segment is
// drawn as a fractal.
//-----------------------------------------------------------------
public void drawFractal ( int order, int x1, int y1, int x5, int y5,
Graphics page)
{
int deltaX, deltaY, x2, y2, x3, y3, x4, y4;

if (order == 1)
page.drawLine (x1, y1, x5, y5);
else
{
deltaX = x5 - x1; // distance between end points
deltaY = y5 - y1;

x2 = x1 + deltaX / 3; // one third
y2 = y1 + deltaY / 3;

x3 = ( int ) ((x1+x5)/2 + SQ * (y1-y5)); // tip of projection
y3 = ( int ) ((y1+y5)/2 + SQ * (x5-x1));

x4 = x1 + deltaX * 2/3; // two thirds
y4 = y1 + deltaY * 2/3;

drawFractal (order-1, x1, y1, x2, y2, page);
drawFractal (order-1, x2, y2, x3, y3, page);
drawFractal (order-1, x3, y3, x4, y4, page);
drawFractal (order-1, x4, y4, x5, y5, page);
}
}

//-----------------------------------------------------------------
// Performs the initial calls to the drawFractal method.
//-----------------------------------------------------------------
public void paintComponent (Graphics page)
{
super .paintComponent (page);

page.setColor (Color.green);

drawFractal (current, TOPX, TOPY, LEFTX, LEFTY, page);
drawFractal (current, LEFTX, LEFTY, RIGHTX, RIGHTY, page);
drawFractal (current, RIGHTX, RIGHTY, TOPX, TOPY, page);
}