Pods/GPUImage/framework/Source/GPUImagePerlinNoiseFilter.m
#import "GPUImagePerlinNoiseFilter.h"

#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 noise
 float 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 permutation
    vec4 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 noise
 float 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 permutation
    vec4 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


@implementation GPUImagePerlinNoiseFilter

@synthesize scale = _scale, colorStart = _colorStart, colorFinish = _colorFinish;

#pragma mark -
#pragma mark Initialization and teardown

- (id)init;
{
    if (!(self = [super initWithFragmentShaderFromString:kGPUImagePerlinNoiseFragmentShaderString]))
    {
		return nil;
    }
    
    scaleUniform = [filterProgram uniformIndex:@"scale"];
    
    colorStartUniform = [filterProgram uniformIndex:@"colorStart"];
    colorFinishUniform = [filterProgram uniformIndex:@"colorFinish"];
    
    [self setScale:8.0];
    
    [self setColorStart:(GPUVector4){0.0, 0.0, 0.0, 1.0}];
    [self setColorFinish:(GPUVector4){1.0, 1.0, 1.0, 1.0}];    
    
    return self;
}

#pragma mark -
#pragma mark Accessors

- (void)setScale:(float)scale 
{
    _scale = scale;
    
    [self setFloat:_scale forUniform:scaleUniform program:filterProgram];
}

- (void)setColorStart:(GPUVector4)colorStart 
{
    _colorStart = colorStart;
    
    [self setVec4:_colorStart forUniform:colorStartUniform program:filterProgram];
}

- (void)setColorFinish:(GPUVector4)colorFinish 
{
    _colorFinish = colorFinish;

    [self setVec4:_colorFinish forUniform:colorFinishUniform program:filterProgram];
}

@end
