feat(package): voronoi: simple voronoi algoritm realization

package/voronoi/README.md

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+```sh
+sh voronoi.sh 500 500 65 "$(sh ./gen-voronoi-points.sh 400 0 0 500 0 0 500)" 0,0,255 255,0,0 \
+| magick -size 200x200 xc:white -draw @- voronoi.png
+```

package/voronoi/gen-voronoi-points.sh

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+#!/bin/sh
+# posix: uniform points in a 2D parallelogram for Voronoi seeds
+# usage: ./gen N x0 y0 ax ay bx by
+# generates N points p = (x0,y0) + u*(ax,ay) + v*(bx,by), with u,v ~ U[0,1)
+
+[ "$#" -eq 7 ] || { echo "usage: $0 N x0 y0 ax ay bx by" >&2; exit 1; }
+
+awk -v n="$1" -v x0="$2" -v y0="$3" -v ax="$4" -v ay="$5" -v bx="$6" -v by="$7" '
+BEGIN{
+  srand();
+  for(i=0;i<n;i++){
+    u = rand(); v = rand();
+    x = int(x0 + u*ax + v*bx);
+    y = int(y0 + u*ay + v*by);
+    printf "%d,%d ", x, y;
+  }
+}'

package/voronoi/voronoi.awk

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+function clamp(v){ return v<0?0:(v>1?1:v) }
+function color_lerp(p, q, r1, g1, b1, r2, g2, b3, x){
+  t = (x - p) / (q - p)
+  t = clamp(t)
+  r = int(r1 + t*(r2 - r1) + 0.5)
+  g = int(g1 + t*(g2 - g1) + 0.5)
+  b = int(b1 + t*(b2 - b1) + 0.5)
+  return sprintf("#%02X%02X%02X", r, g, b)
+}
+BEGIN {
+  # external variables
+  # PTS  is voronoi centers
+  # W    is canvas width
+  # H    is canvas height
+  # FADE is fade max distance
+  # C1   is first color in gradient
+  # C2   is secont color in gradient
+
+  if (C1 == "") C1 = "0,0,0"
+  if (C2 == "") C2 = "255,255,255"
+  split(C1, c1, ",")
+  split(C2, c2, ",")
+
+  n = split(PTS, pairs, " ")
+  for (i = 1; i <= n; ++i) {
+    split(pairs[i], xy, ",")
+    px[i] = xy[1] + 0
+    py[i] = xy[2] + 0
+  }
+
+  for (y = 0; y < H; y++)
+    for (x = 0; x < W; x++) {
+      min_d = 1e308
+      for (i = 1; i <= n; i++) {
+        dx = x - px[i]
+        dy = y - py[i]
+        d = sqrt(dx*dx + dy*dy)
+        if (d < min_d)
+          min_d = d
+      }
+
+      fade = FADE - min_d
+      if (fade < 0) fade = 0
+
+      color = color_lerp(0, FADE, c1[1],c1[2],c1[3], c2[1],c2[2],c2[3], fade)
+
+      printf "fill %s point %d,%d\n", color, x, y
+    }
+}

package/voronoi/voronoi.frag

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+#define PTS_N 500
+#define
+
+// Author @patriciogv - 2015
+// http://patriciogonzalezvivo.com
+
+#ifdef GL_ES
+precision mediump float;
+#endif
+
+uniform vec2 u_resolution;
+uniform vec2 u_mouse;
+uniform float u_time;
+
+float random (vec2 st) {
+    return fract(sin(dot(st.xy, vec2(12.9898,78.233)))*43758.5453123);
+}
+
+void mainImage( out vec4 fragColor, in vec2 fragCoord )
+{
+      vec2 st = gl_FragCoord.xy/u_resolution.xy;
+
+      float rnd = random( st );
+
+      for(i=0;i<PTS_N;i++){
+        u = rnd(); v = rnd();
+        x = int(x0 + u*ax + v*bx);
+        y = int(y0 + u*ay + v*by);
+        printf "%d,%d ", x, y;
+      }
+
+      min_d = 1e308
+      for (i = 1; i <= n; i++) {
+        dx = x - px[i]
+        dy = y - py[i]
+        d = sqrt(dx*dx + dy*dy)
+        if (d < min_d)
+          min_d = d
+      }
+
+      fade = FADE - min_d
+      if (fade < 0) fade = 0
+
+      color = color_lerp(0, FADE, c1[1],c1[2],c1[3], c2[1],c2[2],c2[3], fade)
+
+      printf "fill %s point %d,%d\n", color, x, y
+
+      //gl_FragColor = vec4(vec3(rnd),1.0);
+}

package/voronoi/voronoi.sh

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+#!/bin/sh
+# Usage: ./voronoi_data.sh WIDTH HEIGHT "x1,y1 x2,y2 ..."
+
+if [ $# -lt 4 ]; then
+  printf 'Usage: %s WIDTH HEIGHT FADE "x1,y1 x2,y2 ..."\n' "$0" >&2
+  exit 1
+fi
+
+W=$1
+H=$2
+FADE=$3
+PTS=$4
+C1=$5
+C2=$6
+
+awk \
+  -v W="$W" \
+  -v H="$H" \
+  -v PTS="$PTS" \
+  -v FADE="$FADE" \
+  -v C1="$C1" \
+  -v C2="$C2" \
+  -f ./voronoi.awk