[Java] 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;
 }
 }
 
}