glitcher

#!/bin/bash

OUT="${1}"
TXT="${*:2}"
GLITCHER_DEBUG="${GLITCHER_DEBUG:-0}"

[ ! -t 0 ] && { read -r TXT; }

function print_help {
  cat <<EOF

$ glitcher FILE TEXT...

eg.
glitcher out.svg hello world
EOF
}

! [[ "$BASH_VERSION" =~ 5.* ]] && {
  echo "[ERROR] Bash v5 or higher is required, found $BASH_VERSION"
  exit 1
}

[ "$OUT" = "" ] || [ "$TXT" = "" ] && {
  echo " [ERROR] bad argument"
  print_help
  exit 1
}

! [ "$OSTYPE" = "linux-gnu" ] && {
  echo "[WARNING] only tested on linux-gnu"
  sleep 3
}

function rnd {
  awk \
    -v s="$RANDOM" \
    -v min="${1:-0}" \
    -v max="${2:-1}" \
    -v neg="${3:-0}" '
        BEGIN {
            srand(s);
            printf"%.2f", min+rand()*(max-min)*(neg==0?1:rand()>.5?1:-1)
        }'
}

function rnd_seq {
  local upper="${1:?BAD}"
  local keys=()
  local vals=''
  local steps="$(((RANDOM % 8) + 8))"
  for ((i = 0; i < steps - 2; i++)); do keys+=("$(rnd 0.08 1)"); done
  mapfile -t keys < <(
    printf '0;\n'
    printf '%s;\n' "${keys[@]}" | sort -g | uniq
  )
  for _ in "${keys[@]}"; do vals+="$(rnd 0.001 "$upper" 1); "; done
  local ks="${keys[*]}"
  printf '%s\n%s' "${ks::(-1)}" "${vals::(-2)}"
}

mapfile -t B_SHIFT < <(rnd_seq 0.016)
mapfile -t R_SHIFT < <(rnd_seq 0.016)
read -r B_DUR < <(rnd 50 60)
read -r R_DUR < <(rnd 55 60)
read -r WIDTH < <(bc <<<"${#TXT} * 17")

((GLITCHER_DEBUG)) && RECT='<rect fill="#ee33aa" width="100%" height="100%" x="0" y="0" />'

cat <<EOF >"$OUT"
<svg xmlns="http://www.w3.org/2000/svg"
     viewBox="0 0 ${WIDTH} 32" >
      <!-- made with glitcher-cli v0.6
        █▀▀ █░░ █ ▀█▀ █▀▀ █░█ █▀▀ █▀█
        █▄█ █▄▄ █ ░█░ █▄▄ █▀█ ██▄ █▀▄
      https://github.com/metaory/glitcher-cli -->
      ${RECT}
      <text filter="url(#glitch)"
            fill="#EEAAFF"
            font-family="monospace, serif"
            font-weight="bolder"
            font-size="x-large"
            text-anchor="middle"
            dominant-baseline="mathematical"
            x="50%" y="42%"
      >${TXT}</text>
      <defs>
      <filter id="glitch"
              primitiveUnits="objectBoundingBox"
              x="-20%"
              y="0%"
              width="120%"
              height="100%">
          <feColorMatrix in="SourceGraphic"
                         result="red"
                         type="matrix"
                         values="1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0" />
          <feColorMatrix in="SourceGraphic"
                         result="green"
                         type="matrix"
                         values="0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 1 0" />
          <feColorMatrix in="SourceGraphic"
                         result="blue"
                         type="matrix"
                         values="0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0" />
          <feOffset in="red"
                    result="red-shifted"
                    dx="-0.01"
                    dy="0">
          <animate attributeName="dx"
                   keyTimes="${R_SHIFT[0]}"
                   values="${R_SHIFT[1]}"
                   begin="0"
                   dur="${R_DUR}s"
                   calcMode="discrete"
                   repeatCount="indefinite"
                   fill="freeze" />
            </feOffset>
            <feOffset in="blue"
                      result="blue-shifted"
                      dx="0.01"
                      dy="0">
                <animate attributeName="dx"
                         keyTimes="${B_SHIFT[0]}"
                         values="${B_SHIFT[1]}"
                         begin="0"
                         dur="${B_DUR}s"
                         calcMode="discrete"
                         repeatCount="indefinite"
                         fill="freeze" />
            </feOffset>
            <feBlend mode="screen"
                     in="red-shifted"
                     in2="green"
                     result="red-green" />
            <feBlend mode="screen"
                     in="red-green"
                     in2="blue-shifted"
                     result="blended" />
EOF

I=0
NW=0
SLICES=()

function put_slice {
  ((I++))
  read -r S1 < <(rnd 6 24)
  read -r S2 < <(rnd 6 16)
  read -r DR < <(rnd 30 60)
  read -r NX < <(bc <<<"$NW + $S1")

  mapfile -t SEQ < <(rnd_seq 0.012)

  SA="slice_${I}a"
  SB="slice_${I}b"
  SLICES+=("$SA" "$SB")

  cat <<EOF >>"$OUT"
    <feOffset in="blended"
              dx="0"
              dy="0"
              y="${NW}%"
              height="${S1}%"
              result="${SA}" />
    <feOffset in="blended"
              dx="0"
              dy="0"
              y="${NX}%"
              height="${S2}%"
              result="${SB}">
        <animate attributeName="dx"
                 keyTimes="${SEQ[0]}"
                 values="${SEQ[1]}"
                 begin="0s"
                 dur="${DR}s"
                 calcMode="discrete"
                 repeatCount="indefinite"
                 fill="freeze" />
    </feOffset>
EOF
  read -r NW < <(bc <<<"($NX + $S2)*1/1")
}

while ((NW <= 100)); do put_slice; done

cat <<<'    <feMerge>' >>"$OUT"

for S in "${SLICES[@]}"; do cat <<<"        <feMergeNode in=""\"${S}\""" />" >>"$OUT"; done

cat <<EOF >>"$OUT"
    </feMerge>
    </filter>
    </defs>
</svg>
EOF

echo "created $OUT successfully."

# vim: ft=bash