VIGNETTES

//natural vignette
//modified from https://www.shadertoy.com/view/4lSXDm

float Falloff = 0.95;     //
float radius = 0.75;      //
vec2 pos = vec2(0.5,0.5); //center of vignette

void mainImage( out vec4 fragColor, in vec2 fragCoord )
{
    vec2 uv = fragCoord.xy / iResolution.xy;
    vec4 color = texture(iChannel0, uv);
    //vec4 color = vec4(1.,1.,1.,1.);
    vec2 coord = (uv - pos) * vec2(iResolution.x/iResolution.y,1.) / radius;
    float rf = 1.0 + dot(coord, coord) * Falloff*Falloff;
    float e = 1.0 / (rf*rf);
  fragColor = vec4(color.rgb * e, 1.0);
}


// 
// modified https://www.shadertoy.com/view/MsySzy
#define FROSTYNESS 2.0
#define COLORIZE   1.0
#define COLOR_RGB  0.7,1.0,1.0

float rand(vec2 uv) {
 
    float a = dot(uv, vec2(92., 80.));
    float b = dot(uv, vec2(41., 62.));
    
    float x = sin(a) + cos(b) * 51.;
    return fract(x);
}

void mainImage( out vec4 fragColor, in vec2 fragCoord )
{
  vec2 uv = fragCoord.xy / iResolution.xy;
    vec4 d = texture(iChannel1, uv);
  vec2 rnd = vec2(rand(uv+d.r*.05), rand(uv+d.b*.05));
    
    //vignette
    const vec2 lensRadius = vec2(0.35*1.42, 0.25);
    //float dist = distance(uv.xy, vec2(0.5,0.5));
    float dist = distance(uv.xy, iMouse.xy/ iResolution.xy );
    float vigfin = pow(1.-smoothstep(lensRadius.x, lensRadius.y, dist),2.);
   
    rnd *= .035*vigfin;
    uv += rnd;
    //uv += rnd + vigfin;  //give lens distorsion around circle
    fragColor = mix(texture(iChannel0, uv),vec4(COLOR_RGB,1.0),0.);
}