绘制大麻曲线
灵感来自数学网站的大麻方程 （它指的是Wolfram Research Cannabis Curve ），我想知道..我们如何使用Java-2D绘制这条曲线？
import java.awt.*; import java.awt.geom.*; import java.awt.image.BufferedImage; import javax.imageio.ImageIO; import javax.swing.*; import java.io.File; /** Draws the CannabisCurve http://mathworld.wolfram.com/CannabisCurve.html Inspired by a question asked at: http://math.stackexchange.com/q/618786/38356 */ class CannabisCurve { double size = 80d; int pad = 5; CannabisCurve() { JOptionPane.showMessageDialog(null, new ImageIcon(getImage())); } /** Returns a point for one angle of the Cannabis Curve. */ public Point2D.Double getPoint(double angle) { double r = getR(angle); return new Point2D.Double(Math.sin(r), Math.cos(r)); } /** Returns the result of the Cannabis Curve equation for an angle * r=(1+0.9cos(8a))(1+0.1cos(24a))(0.9+0.1cos(200a))(1+sin(a)) * Where 'a' represents the angle. */ public double getR(double angle) { double r = (1 + 0.9 * Math.cos(8 * angle)) * (1 + (0.1 * Math.cos(24 * angle))) * (0.9 + (0.1 * Math.cos(200 * angle))) * (1 + Math.sin(angle)); return r * size; } /** Returns a GeneralPath that traces the Cannabis Curve */ public GeneralPath getCannabisCurve() { GeneralPath gp = new GeneralPath(); boolean first = true; for (double a = 0.0; a < 2 * Math.PI; a += .001) { double r = getR(a); double x = (Math.sin(a) * r); double y = (Math.cos(a) * r); if (first) { gp.moveTo(x, y); first = false; } else { gp.lineTo(x, y); } } gp.closePath(); // the trace is complete, now we need to transform it. AffineTransform rotate = AffineTransform.getRotateInstance( 3 * Math.PI / 2); gp.transform(rotate); Rectangle r = gp.getBounds(); System.out.println(r); int imageWidth = r.width + (2 * pad); int imageHeight = r.height + (2 * pad); int size = (imageWidth > imageHeight ? imageWidth : imageHeight); int difference = Math.abs(imageWidth - imageHeight) / 2; AffineTransform translate = AffineTransform.getTranslateInstance( -(rx - (pad)), -(ry - (pad + difference))); gp.transform(translate); return gp; } /** Turns the Cannabis Curve into an image */ public BufferedImage getImage() { GeneralPath gp = getCannabisCurve(); Rectangle r = gp.getBounds(); int size = r.width+(2*pad); BufferedImage bg = new BufferedImage( size, size, BufferedImage.TYPE_INT_RGB); Graphics2D g = bg.createGraphics(); g.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); g.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY); g.setRenderingHint(RenderingHints.KEY_COLOR_RENDERING, RenderingHints.VALUE_COLOR_RENDER_QUALITY); g.setStroke(new BasicStroke(1.5f)); g.setColor(Color.WHITE); g.fillRect(0, 0, size, size); g.setColor(Color.GREEN.darker()); g.fill(gp); g.setColor(Color.GREEN.darker().darker()); g.draw(gp); g.dispose(); try { ImageIO.write(bg, "png", new File("CannabisCurve.png")); } catch(Exception e) { e.printStackTrace(); } return bg; } public static void main(String[] args) { Runnable r = new Runnable() { @Override public void run() { new CannabisCurve(); } }; // Swing GUIs should be created and updated on the EDT // http://docs.oracle.com/javase/tutorial/uiswing/concurrency SwingUtilities.invokeLater(r); } }