java实现水波纹扩散效果

package com.gloomyfish.filter.study; import java.awt.image.BufferedImage; public class WaterFilter extends AbstractBufferedImageOp { private float wavelength = 16; private float amplitude = 10; private float phase = 0; private float centreX = 0.5f; private float centreY = 0.5f; private float radius = 50;  private float radius2 = 0; private float icentreX; private float icentreY;  public WaterFilter() {  }  @Override public BufferedImage filter(BufferedImage src, BufferedImage dest) { 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 ); icentreX = width * centreX; icentreY = height * centreY; if ( radius == 0 ) radius = Math.min(icentreX, icentreY); radius2 = radius*radius;  int index = 0;  float[] out = new float[2];  for(int row=0; row<height; row++) {   for(int col=0; col<width; col++) {   index = row * width + col;      // 获取水波的扩散位置，最重要的一步   generateWaterRipples(col, row, out); int srcX = (int)Math.floor( out[0] ); int srcY = (int)Math.floor( out[1] ); float xWeight = out[0]-srcX; float yWeight = out[1]-srcY; int nw, ne, sw, se;  // 获取周围四个像素，插值用， if ( srcX >= 0 && srcX < width-1 && srcY >= 0 && srcY < height-1) {  // Easy case, all corners are in the image  int i = width*srcY + srcX;  nw = inPixels[i];  ne = inPixels[i+1];  sw = inPixels[i+width];  se = inPixels[i+width+1]; } else {  // Some of the corners are off the image  nw = getPixel( inPixels, srcX, srcY, width, height );  ne = getPixel( inPixels, srcX+1, srcY, width, height );  sw = getPixel( inPixels, srcX, srcY+1, width, height );  se = getPixel( inPixels, srcX+1, srcY+1, width, height ); }  // 取得对应的振幅位置P(x, y)的像素，使用双线性插值 /*if(xWeight >=0 || yWeight >= 0) {  outPixels[index] = ImageMath.bilinearInterpolate(xWeight, yWeight, nw, ne, sw, se);   } else  {  outPixels[index] = inPixels[index]; }*/ outPixels[index] = ImageMath.bilinearInterpolate(xWeight, yWeight, nw, ne, sw, se);   }  }   setRGB( dest, 0, 0, width, height, outPixels );  return dest; }  private int getPixel(int[] pixels, int x, int y, int width, int height) { if (x < 0 || x >= width || y < 0 || y >= height) { return 0; // 有点暴力啦，懒得管啦 } return pixels[ y*width+x ]; }  protected void generateWaterRipples(int x, int y, float[] out) { float dx = x-icentreX; float dy = y-icentreY; float distance2 = dx*dx + dy*dy; // 确定 water ripple的半径，如果在半径之外，就直接获取原来位置，不用计算迁移量 if (distance2 > radius2) {  out[0] = x; out[1] = y; } else { // 如果在radius半径之内，计算出来 float distance = (float)Math.sqrt(distance2); // 计算改点振幅 float amount = amplitude * (float)Math.sin(distance / wavelength * ImageMath.TWO_PI - phase); // 计算能量损失，  amount *= (radius-distance)/radius; // 计算能量损失， if ( distance != 0 ) amount *= wavelength/distance; // 得到water ripple 最终迁移位置 out[0] = x + dx*amount; out[1] = y + dy*amount; } } }