at last voronoi distance

processing_app/topics/shaders/data/voronoi_distance.glsl

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+// After Inigo Quilez adapted for processing by Martin Prout
+// The MIT License
+// Copyright © 2013 Inigo Quilez
+
+#ifdef GL_ES
+precision mediump float;
+precision mediump int;
+#endif
+
+uniform vec3      iResolution;
+uniform float     iTime;
+uniform sampler2D texture;
+
+void mainImage( out vec4 fragColor, in vec2 fragCoord );
+
+void main() {
+  mainImage(gl_FragColor,gl_FragCoord.xy);
+}
+
+vec2 hash2( vec2 p )
+{
+  // procedural white noise
+  return fract(sin(vec2(dot(p,vec2(127.1,311.7)),dot(p,vec2(269.5,183.3))))*43758.5453);
+}
+
+vec3 voronoi( in vec2 x )
+{
+  vec2 n = floor(x);
+  vec2 f = fract(x);
+
+  //----------------------------------
+  // first pass: regular voronoi
+  //----------------------------------
+  vec2 mg, mr;
+
+  float md = 8.0;
+  for( int j=-1; j<=1; j++ )
+  for( int i=-1; i<=1; i++ )
+  {
+    vec2 g = vec2(float(i),float(j));
+    vec2 o = 0.5 + 0.5*sin( iTime + 6.2831 * hash2( n + g ));
+    vec2 r = g + o - f;
+    float d = dot(r,r);
+    if( d<md )
+    {
+      md = d;
+      mr = r;
+      mg = g;
+    }
+  }
+
+  //----------------------------------
+  // second pass: distance to borders
+  //----------------------------------
+  md = 8.0;
+  for( int j=-2; j<=2; j++ )
+  for( int i=-2; i<=2; i++ )
+  {
+    vec2 g = mg + vec2(float(i),float(j));
+    vec2 o = 0.5 + 0.5*sin( iTime + 6.2831 * hash2( n + g ) );
+    vec2 r = g + o - f;
+    if( dot(mr-r,mr-r)>0.00001 )
+    md = min( md, dot( 0.5*(mr+r), normalize(r-mr) ) );
+  }
+  return vec3( md, mr );
+}
+
+void mainImage( out vec4 fragColor, in vec2 fragCoord )
+{
+  vec2 p = fragCoord/iResolution.xx;
+
+  vec3 c = voronoi( 8.0*p );
+
+  // isolines
+  vec3 col = c.x*(0.5 + 0.5*sin(64.0*c.x))*vec3(1.0);
+  // borders
+  col = mix( vec3(1.0,0.6,0.0), col, smoothstep( 0.04, 0.07, c.x ) );
+  // feature points
+  float dd = length( c.yz );
+  col = mix( vec3(1.0,0.6,0.1), col, smoothstep( 0.0, 0.12, dd) );
+  col += vec3(1.0,0.6,0.1)*(1.0-smoothstep( 0.0, 0.04, dd));
+
+  fragColor = vec4(col,1.0);
+}

processing_app/topics/shaders/voronoi_distance.rb

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+#!/usr/bin/env jruby -v -W2
+# frozen_string_literal: true
+require 'propane'
+
+##
+# Voronoi Distance.
+#
+# GLSL version of the 1k intro Voronoi from the demoscene
+# (http://www.pouet.net/prod.php?which=52761)
+# Ported from the webGL version available in ShaderToy:
+# http://www.iquilezles.org/apps/shadertoy/
+# (Look for Voronoi under the Plane Deformations Presets)
+class VoronoiDistance < Propane::App
+  attr_reader :voronoi
+
+  def setup
+    sketch_title 'Voronoi Distance'
+    no_stroke
+    @voronoi = load_shader(data_path('voronoi_distance.glsl'))
+    voronoi.set('iResolution', width.to_f, height.to_f, 0.0)
+  end
+
+  def draw
+    voronoi.set('iTime', millis / 1000.0)
+    shader(voronoi)
+    # This kind of effects are entirely implemented in the
+    # fragment shader, they only need a quad covering the
+    # entire view area so every pixel is pushed through the
+    # shader.
+    rect(0, 0, width, height)
+  end
+
+  def settings
+    size(640, 360, P2D)
+  end
+end
+
+VoronoiDistance.new