基于Java语言模拟水波纹运动效果，分为两种方法，一种采用简单的叠加计算
不使用sine函数模拟水波纹，好处是计算量小，另外一种采用sine函数来计算
水波纹扩展，计算量大，但是效果比较真实。
第一种简单的叠加效果水波模拟，是很多简单的2D游戏中会用的，关键是计
算水波的迁移，然后剩以能量衰减因子。Java实现的代码如下：
for(y=1; y<waveWidth-1; y++) { for(x= 1; x<waveHeight-1; x++) { int n = (waveMapData[current][y-1][x] + waveMapData[current][y+1][x] + waveMapData[current][y][x+1] + waveMapData[current][y][x-1])/2 - waveMapData[before][y][x]; // energy lost n = n - n / damp; /*if(Math.abs(n) >= Math.abs(-100)) { n = n % Math.abs(-100); }*/ waveMapData[next][y][x] = n; // System.out.print(" " + n); } // System.out.println(); }
解释：
主要是利用前两个水波的位置，计算出下一个将要出现的水波的位置，因此非常
重要的是保存前两个水波的迁移信息，然后实现波的叠加计算，在加上能量损失
因子，即可获得下个波的位置。
这种方法模拟出来的水波不是很圆，如果想得到那种很圆的水波效果，建议看
这里：http://blog.csdn.net/jia20003/article/details/13159535
解释完水波模拟的原理部分，下面来说说JAVA Swing的动画原理
主要是利用一个线程来计算水波的新位置，然后重新绘制图片，图片绘制好
以后调用repaint（）方法，自动触发Swing重绘机制，实现刷新显示效果。
水波计算线程代码如下：
Thread animationThread = new Thread () { @Override public void run() { int k = 0; while (true) { startWaterWave(); // sinWaterRipple(); updateText("水波开展：" + k); repaint(); // Refresh the display try { Thread.sleep(1000 / 30); // delay and yield to other threads } catch (InterruptedException ex) { } k++; if(k>=100){ break; } } } }; animationThread.start();
最后说一下Java的一个数据Copy的函数System.arraycopy，如果在多维数据中交
换数据你可能发现由于它是指针交换，交换完以后对新的数组赋值会同时跑到旧的
里面去。这个是我在debug程序的时候才发现。惭愧啊！程序效果如下：
UI加水波计算的完全源代码如下：
package com.gloomyfish.water.ripple.study; import java.awt.BorderLayout; import java.awt.Dimension; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.RenderingHints; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.image.BufferedImage; import java.io.File; import javax.imageio.ImageIO; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.JPanel; import javax.swing.SwingUtilities; import com.gloomyfish.filter.study.WaterFilter; public class MyDemoUI extends JFrame implements ActionListener { /** * */ private static final long serialVersionUID = -3702707300863726479L; private BufferedImage textureImg = null; private BufferedImage resultImg = null; private int waveWidth = 40; private int waveHeight = 40; private int damp = 16; private int[][][] waveMapData; private int before = 0, current = 1, next = 2; private int x = 1, y = 1 /*n = 0*/; private WaterPixelRender imageRender; private WaterFilter filter; private JButton runBtn; private JLabel txtLabel; private boolean text = false; public MyDemoUI() { super("Water Ripple"); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); getContentPane().setLayout(new BorderLayout()); // Display the window. getContentPane().add(createWaterPanel(), BorderLayout.CENTER); runBtn = new JButton("Run it"); runBtn.addActionListener(this); txtLabel = new JLabel(); txtLabel.setText("水纹：0"); getContentPane().add(runBtn, BorderLayout.SOUTH); getContentPane().add(txtLabel, BorderLayout.NORTH); setPreferredSize(new Dimension(300 + 25,500)); pack(); setVisible(true); } public void updateText(String textContent) { txtLabel.setText(textContent); this.invalidate(); } private JPanel createWaterPanel() { try { File file = new File("D:\\resource\\flower_001.png"); textureImg = ImageIO.read(file); resultImg = textureImg; } catch (Exception e) { e.printStackTrace(); } imageRender = new WaterPixelRender(); filter = new WaterFilter(); JPanel wPanel = new JPanel() { protected void paintComponent(Graphics g) { Graphics2D g2 = (Graphics2D) g; g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); if (resultImg != null) { g2.drawImage(resultImg, 0, 0, resultImg.getWidth(), resultImg.getHeight(), null); } } }; return wPanel; } public void swapData() { for(int i=0; i<waveWidth; i++) { for(int j=0; j<waveHeight; j++) { waveMapData[before][i][j] = waveMapData[current][i][j]; waveMapData[current][i][j] = waveMapData[next][i][j]; } } } public void simulateWaterRipple() { x = 1; y = 1; //n = 0; waveMapData = new int[3][textureImg.getHeight()][textureImg.getWidth()]; waveWidth = textureImg.getHeight(); waveHeight = textureImg.getWidth(); for(int i=0; i<waveWidth; i++) { for(int j=0; j<waveHeight; j++) { waveMapData[next][i][j] = 0; waveMapData[current][i][j] = 0; waveMapData[before][i][j] = 0; } } waveMapData[current][waveWidth/2][waveHeight/2] = -300; Thread animationThread = new Thread () { @Override public void run() { int k = 0; while (true) { startWaterWave(); // sinWaterRipple(); updateText("水波开展：" + k); repaint(); // Refresh the display try { Thread.sleep(1000 / 30); // delay and yield to other threads } catch (InterruptedException ex) { } k++; if(k>=100){ break; } } } }; animationThread.start(); } protected void sinWaterRipple() { resultImg = filter.filter(textureImg, null); filter.setRadius(filter.getRadius() + 5); if(filter.getRadius() > 150) { filter.setRadius(50); } float wl = filter.getWavelength(); if(wl > 4) { wl = wl / 2; } else { wl = 32; } filter.setWavelength(wl); } protected void startWaterWave(/*int sx, int sy, Graphics2D g2*/) { for(y=1; y<waveWidth-1; y++) { for(x= 1; x<waveHeight-1; x++) { int n = (waveMapData[current][y-1][x] + waveMapData[current][y+1][x] + waveMapData[current][y][x+1] + waveMapData[current][y][x-1])/2 - waveMapData[before][y][x]; // energy lost n = n - n / damp; // if(Math.abs(n) >= Math.abs(-100)) // { // n = n % Math.abs(-100); // } waveMapData[next][y][x] = n; // System.out.print(" " + n); } // System.out.println(); } // render image pixel and display water ripple at here imageRender.setWaveData(waveMapData[next]); resultImg = imageRender.filter(textureImg, null); // prepare for the next water ripple // Java System.arraycopy give very bad result due to reference issue!!!! // System.arraycopy(waveMapData[next], 0, waveMapData[current], 0, waveMapData[next].length); swapData(); } public static void main(String[] args) { new MyDemoUI(); } @Override public void actionPerformed(ActionEvent e) { SwingUtilities.invokeLater(new Runnable() { public void run(){ simulateWaterRipple(); } }); } }
绘制水波像素的生产新图片的代码如下：
package com.gloomyfish.water.ripple.study; import java.awt.image.BufferedImage; import com.gloomyfish.filter.study.AbstractBufferedImageOp; public class WaterPixelRender extends AbstractBufferedImageOp { private int[][] waveData; private double rIndex = 2.0; private int counter = 0; public WaterPixelRender() { } public int[][] getWaveData() { return waveData; } public void setWaveData(int[][] waveData) { this.waveData = waveData; } @Override public BufferedImage filter(BufferedImage src, BufferedImage dest) { counter++; int width = src.getWidth(); int height = src.getHeight(); if ( dest == null ) dest = createCompatibleDestImage( src, null ); int[] inPixels = new int[width*height]; int[] outPixels = new int[width*height]; getRGB( src, 0, 0, width, height, inPixels ); int index = 0; int nrow = 0, ncol = 0; for(int row=0; row<height-1; row++) { int ta = 0, tr = 0, tg = 0, tb = 0; for(int col=0; col<width-1; col++) { int xDiff = waveData[row+1][col] - waveData[row][col]; int yDiff = waveData[row][col+1] - waveData[row][col]; double xAngle = Math.atan(xDiff); double xRefraction = Math.asin( Math.sin( xAngle ) / rIndex ); double xDisplace = Math.tan( xRefraction ) * xDiff ; double yAngle = Math.atan( yDiff ); double yRefraction = Math.asin( Math.sin( yAngle ) / rIndex ); double yDisplace =Math.tan(yRefraction ) * yDiff; if(xDiff < 0) { if(yDiff < 0) { nrow = (int)(row - xDisplace); ncol = (int)(col - yDisplace); } else { nrow = (int)(row - xDisplace); ncol = (int)(col + yDisplace); } } else { if(yDiff < 0) { nrow = (int)(row + xDisplace); ncol = (int)(col - yDisplace); } else { nrow = (int)(row + xDisplace); ncol = (int)(col + yDisplace); } } if(nrow < 0 || nrow >= height) { nrow = 0; } if(ncol < 0 || ncol >= width) { ncol = 0; } index = nrow * width + ncol; ta = (inPixels[index] >> 24) & 0xff; tr = (inPixels[index] >> 16) & 0xff; tg = (inPixels[index] >> 8) & 0xff; tb = inPixels[index] & 0xff; index = row * width + col; outPixels[index] = (ta << 24) | (tr << 16) | (tg << 8) | tb; } } setRGB( dest, 0, 0, width, height, outPixels ); return dest; } }
复制代码以后替换图片路径即可运行，转载请注明出处
