java实现水波纹扩散效果

java实现水波纹扩散效果

一、原理

模拟水波纹效果，最常见的是sine或者cosn的函数，周期性变化，贴近自然。

当水波纹中中间开始向四周扩散的时候，一般都是慢慢的失去能量，振幅也是越来越小，所以程序要模拟这个过程时候，要加上一个能量递减因子。然后用公式 y = a*sine(bx + c)来表示波纹公式。

二、程序实现

最重要的一步是计算水波纹的振幅。在任意一点确定水波的中心位置，可以是鼠标随机选取，对半径范围内的像素位置实现水波生成，然后转换为位置，对位置实现浮点数取整，然后使用适当的插值算法，本例使用双线性插值。

三、程序效果

四、滤镜完全源代码

这次我写了些中文注解，不给源代码的博文不是好博文

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

for(int col=0; 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)http://

{

outPUAndMPixels[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;

}

}

}

for(int col=0; 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)http://

{

outPUAndMPixels[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;

}

}

}

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)http://

{

outPUAndMPixels[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;

}

}

}

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