Ripples¶

/* The original way
void mainImage( out vec4 fragColor, in vec2 fragCoord ) {
     float t = mod(iTime, 3.);
     vec3 waveParams = vec3( 10.0, 0.8, 0.1 );
     vec2 uv = fragCoord.xy / iResolution.xy;
     uv = uv * 2. - 1.;
     vec2 texCoord = uv;
     float distance = length(uv);

     if ( distance <= t + waveParams.z && distance >= t - waveParams.z )
     {
            float diff = distance - t;
            float powDiff = 1.0 - pow(abs(diff*waveParams.x), waveParams.y);

            float diffTime = diff  * powDiff;
            vec2 diffUV = normalize(uv);
            texCoord = uv + (diffUV * diffTime);

     }
     vec4 original = texture( iChannel0, texCoord);
     fragColor = original;
}
*/
void mainImage( out vec4 fragColor, in vec2 fragCoord ) {
     float t = mod(iTime, 3.);
     vec3 waveParams = vec3( 10.0, 0.8, 0.1 );
     vec2 uv = fragCoord.xy / iResolution.xy;
     // uv = uv * 2. - 1.;
     vec2 texCoord = uv;
     float distance = length(uv * 2. -1.);

     float d = smoothstep(t - 0.06, t, distance);
          d -= smoothstep(t, t + 0.03, distance);
     texCoord = uv * (1. + 0.0125 * d / pow(distance, 1.6));

     vec4 original = texture( iChannel0, texCoord);
     fragColor = original;
}

// Ref: http://adrianboeing.blogspot.in/2011/02/ripple-effect-in-webgl.html
void mainImage( out vec4 fragColor, in vec2 fragCoord )
{
    // pixel position normalised to [-1, 1]
    vec2 cPos = -.5 + 2.0 * fragCoord.xy / iResolution.xy;

    // distance of current pixel from center
    float cLength = length(cPos);

    // vec2 uv = fragCoord.xy/iResolution.xy+(cPos/pow(cLength, 2.))*cos(cLength*12.0-iTime*4.0) * 0.03;

    vec2 uv = fragCoord.xy/iResolution.xy;
    // abs(0.75*sin(2*x)/x + 1*sin(0.5*x)/x) / 1.75
    float s = iTime * 0.125;
    uv += (cPos/pow(cLength, 2.))*cos(cLength*12.0-iTime*14.0) * 0.03
          * abs(0.75*sin(s)/s + sin(0.5*s)/(0.5*s)) / 1.75;
    vec3 col = texture(iChannel0,uv).xyz;

    fragColor = vec4(col,1.0);
}