【发布时间】：2014-12-03 04:24:29
【问题描述】：
我遇到的问题是输出 png 只在左下角显示递归，我不知道为什么。有人可以指点我正确的方向吗，对于凌乱的 cmets 感到抱歉。 谢谢。
import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import javax.imageio.ImageIO;
public class Assignment12 {
static int WIDTH = 0;
static int HEIGHT = 0;
static ArrayList<Double> points = new ArrayList<Double>();
public static void main(String[] args) {
if (args.length == 0) {
WIDTH = 800;
HEIGHT = 693;
} else {
Integer W = Integer.valueOf(args[0]);
Integer H = Integer.valueOf(args[0]);
WIDTH = W;
HEIGHT = H;
}
// DONE //*********stuff to do ***********create the final ordered pairs
// of the biggest triangle
// done// *********stuff to do *********** set the values of the ordered
// pairs
// to the dimensions of the rectangle
final double topX = WIDTH / 2;
final double topY = 0;
final double leftX = 0;
final double leftY = HEIGHT - 1;
final double rightX = WIDTH - 1;
final double rightY = HEIGHT - 1;
sierpinski(topX, topY, leftX, leftY, rightX, rightY);
// ##############jeffs code#########
// BufferedImage creates memory space for storing image data
BufferedImage img = new BufferedImage(WIDTH, HEIGHT,
BufferedImage.TYPE_INT_RGB);
// Graphics2D provides a canvas on which to draw shapes, text, other
// images
Graphics2D g2d = img.createGraphics();
// *********stuff to do *********** do the back ground stuffs
// Clear background to white
g2d.setColor(Color.white);
g2d.fillRect(0, 0, WIDTH, HEIGHT);
// start drawing lines in the correct color.
// Red line from where to where?
g2d.setColor(Color.red);
for (int i = 0; i < points.size(); i = i + 4) {
g2d.drawLine(points.get(i).intValue(),
points.get(i + 1).intValue(), points.get(i + 2).intValue(),
points.get(i + 3).intValue());
}
// g2d.drawLine(0, 0, WIDTH - 1, HEIGHT - 1);
// done// *********stuff to do *********** initialize the recursive
// function to
// done// *********stuff to do *********** get rid of these oval things
// there
// just for reference,
// Draw some random ovals
// for (int i = 0; i < 100; i++) {
// g2d.setColor(new Color((float) Math.random(),
// (float) Math.random(), (float) Math.random()));
// g2d.fillOval((int) (Math.random() * WIDTH),
// (int) (Math.random() * HEIGHT), (int) (Math.random() * 50),
// (int) (Math.random() * 50));
// }
// Finalize the canvas
g2d.dispose();
// Write the image out as a PNG-format file
try {
ImageIO.write(img, "png", new File("out.png"));
} catch (IOException e) {
e.printStackTrace();
}
}
// *********stuff to do *********** create the recursive function for the
// triangles
private static void sierpinski(double topX, double topY, double leftX,
double leftY, double rightX, double rightY) {
// base case area of the triangle reaches x
// (Ax(By-Cy)+Bx(Cy-Ay)+Cx(Ay-By))/2
if (((leftX * (topY - rightY)) + (topX * (rightY - leftY)) + (rightX * (leftY - topY)) / 2) > 10) {// <--
// that 10 should be a static value or just pulled directly from
// args
// start recursive for all three respective points
double leftMidX = (topX + leftX) / 2;
double leftMidY = (topY + leftY) / 2;
double rightMidX = (topX + rightX) / 2;
double rightMidY = (topY + rightY) / 2;
// ***these are just called topMid for convenience. they are the mid
// point values to the bottom line of the triangle.
double botMidX = (leftX + rightX) / 2;
double botMidY = (leftY + rightY) / 2;
// top ... top stays the same
sierpinski(topX, topY, leftMidX, leftMidY, rightMidX, rightMidY);
// left
sierpinski(leftMidX, leftMidY, leftX, leftY, botMidX, botMidY);
// right
sierpinski(rightMidX, rightMidY, botMidX, botMidY, rightX, rightY);
} else {
points.add(topX);
points.add(topY);
points.add(rightX);
points.add(rightY);
points.add(topX);
points.add(topY);
points.add(leftX);
points.add(leftY);
points.add(leftX);
points.add(leftY);
points.add(rightX);
points.add(rightY);
// draw the lines
// g2d.drawLine(topX, topY, rightX, rightY);// right
// g2d.drawLine(topX, topY, leftX, leftY);// left
// g2d.drawLine(leftX, leftY, rightX, rightY);// bot
}
}
}
【问题讨论】：
标签： java recursion bufferedimage graphics2d fractals