IOS – OpenGL ES 图像柏林噪点/花边噪点 GPUImagePerlinNoiseFilter

一.简介
二.效果演示
三.源码下载
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一.简介

GPUImage 共 125 个滤镜, 分为四类

1、Color adjustments : 31 filters , 颜色处理相关
2、Image processing : 40 filters , 图像处理相关.
3、Blending modes : 29 filters , 混合模式相关.
4、Visual effects : 25 filters , 视觉效果相关.

GPUImagePerlinNoiseFilter 属于 GPUImage 图像视觉效果相关，用来处理图像柏林噪点/花边噪点。shader 源码如下：

/******************************************************************************************/
//@Author:猿说编程
//@Blog(个人博客地址): www.codersrc.com
//@File:IOS – OpenGL ES 图像柏林噪点/花边噪点 GPUImagePerlinNoiseFilter
//@Time:2022/06/08 06:30
//@Motto:不积跬步无以至千里，不积小流无以成江海，程序人生的精彩需要坚持不懈地积累！
/******************************************************************************************/#if TARGET_IPHONE_SIMULATOR || TARGET_OS_IPHONE
NSString *const kGPUImagePerlinNoiseFragmentShaderString = SHADER_STRING
(precision highp float;varying highp vec2 textureCoordinate;uniform float scale;uniform vec4 colorStart;uniform vec4 colorFinish;//// Description : Array and textureless GLSL 2D/3D/4D simplex// noise functions.// Author : Ian McEwan, Ashima Arts.// Maintainer : ijm// Lastmod : 20110822 (ijm)// License : Copyright (C) 2011 Ashima Arts. All rights reserved.// Distributed under the MIT License. See LICENSE file.// https://github.com/ashima/webgl-noise//vec4 mod289(vec4 x)
{return x - floor(x * (1.0 / 289.0)) * 289.0;
}vec4 permute(vec4 x)
{return mod289(((x*34.0)+1.0)*x);
}vec4 taylorInvSqrt(vec4 r)
{return 1.79284291400159 - 0.85373472095314 * r;
}vec2 fade(vec2 t) {return t*t*t*(t*(t*6.0-15.0)+10.0);}// Classic Perlin noisefloat cnoise(vec2 P)
{vec4 Pi = floor(P.xyxy) + vec4(0.0, 0.0, 1.0, 1.0);vec4 Pf = fract(P.xyxy) - vec4(0.0, 0.0, 1.0, 1.0);Pi = mod289(Pi); // To avoid truncation effects in permutationvec4 ix = Pi.xzxz;vec4 iy = Pi.yyww;vec4 fx = Pf.xzxz;vec4 fy = Pf.yyww;vec4 i = permute(permute(ix) + iy);vec4 gx = fract(i * (1.0 / 41.0)) * 2.0 - 1.0 ;vec4 gy = abs(gx) - 0.5 ;vec4 tx = floor(gx + 0.5);gx = gx - tx;vec2 g00 = vec2(gx.x,gy.x);vec2 g10 = vec2(gx.y,gy.y);vec2 g01 = vec2(gx.z,gy.z);vec2 g11 = vec2(gx.w,gy.w);vec4 norm = taylorInvSqrt(vec4(dot(g00, g00), dot(g01, g01), dot(g10, g10), dot(g11, g11)));g00 *= norm.x;g01 *= norm.y;g10 *= norm.z;g11 *= norm.w;float n00 = dot(g00, vec2(fx.x, fy.x));float n10 = dot(g10, vec2(fx.y, fy.y));float n01 = dot(g01, vec2(fx.z, fy.z));float n11 = dot(g11, vec2(fx.w, fy.w));vec2 fade_xy = fade(Pf.xy);vec2 n_x = mix(vec2(n00, n01), vec2(n10, n11), fade_xy.x);float n_xy = mix(n_x.x, n_x.y, fade_xy.y);return 2.3 * n_xy;
}void main(){float n1 = (cnoise(textureCoordinate * scale) + 1.0) / 2.0;vec4 colorDiff = colorFinish - colorStart;vec4 color = colorStart + colorDiff * n1;gl_FragColor = color;}
);
#else
NSString *const kGPUImagePerlinNoiseFragmentShaderString = SHADER_STRING
(varying vec2 textureCoordinate;uniform float scale;uniform vec4 colorStart;uniform vec4 colorFinish;//// Description : Array and textureless GLSL 2D/3D/4D simplex// noise functions.// Author : Ian McEwan, Ashima Arts.// Maintainer : ijm// Lastmod : 20110822 (ijm)// License : Copyright (C) 2011 Ashima Arts. All rights reserved.// Distributed under the MIT License. See LICENSE file.// https://github.com/ashima/webgl-noise//vec4 mod289(vec4 x)
{return x - floor(x * (1.0 / 289.0)) * 289.0;
}vec4 permute(vec4 x)
{return mod289(((x*34.0)+1.0)*x);
}vec4 taylorInvSqrt(vec4 r)
{return 1.79284291400159 - 0.85373472095314 * r;
}vec2 fade(vec2 t) {return t*t*t*(t*(t*6.0-15.0)+10.0);}// Classic Perlin noisefloat cnoise(vec2 P)
{vec4 Pi = floor(P.xyxy) + vec4(0.0, 0.0, 1.0, 1.0);vec4 Pf = fract(P.xyxy) - vec4(0.0, 0.0, 1.0, 1.0);Pi = mod289(Pi); // To avoid truncation effects in permutationvec4 ix = Pi.xzxz;vec4 iy = Pi.yyww;vec4 fx = Pf.xzxz;vec4 fy = Pf.yyww;vec4 i = permute(permute(ix) + iy);vec4 gx = fract(i * (1.0 / 41.0)) * 2.0 - 1.0 ;vec4 gy = abs(gx) - 0.5 ;vec4 tx = floor(gx + 0.5);gx = gx - tx;vec2 g00 = vec2(gx.x,gy.x);vec2 g10 = vec2(gx.y,gy.y);vec2 g01 = vec2(gx.z,gy.z);vec2 g11 = vec2(gx.w,gy.w);vec4 norm = taylorInvSqrt(vec4(dot(g00, g00), dot(g01, g01), dot(g10, g10), dot(g11, g11)));g00 *= norm.x;g01 *= norm.y;g10 *= norm.z;g11 *= norm.w;float n00 = dot(g00, vec2(fx.x, fy.x));float n10 = dot(g10, vec2(fx.y, fy.y));float n01 = dot(g01, vec2(fx.z, fy.z));float n11 = dot(g11, vec2(fx.w, fy.w));vec2 fade_xy = fade(Pf.xy);vec2 n_x = mix(vec2(n00, n01), vec2(n10, n11), fade_xy.x);float n_xy = mix(n_x.x, n_x.y, fade_xy.y);return 2.3 * n_xy;}void main(){float n1 = (cnoise(textureCoordinate * scale) + 1.0) / 2.0;vec4 colorDiff = colorFinish - colorStart;vec4 color = colorStart + colorDiff * n1;gl_FragColor = color;}
);
#endif