Cheap Sketch file version control with Git + Kaleidoscope

.gitconfig

# Add this to your .git/config file

[diff]
  tool = SketchKaleidoscope
[difftool "SketchKaleidoscope"]
  cmd = ./util-sketch-kaleidoscope-diff.bash \"$MERGED\" \"$LOCAL\" \"$REMOTE\"

util-sketch-kaleidoscope-diff.bash

#!/bin/bash
# Check this file into your git repo
MERGED="$1"
FILE_1="$2"
FILE_2="$3"

BASENAME=`basename "$MERGED"`
BASENAME="${BASENAME%.sketch}"

# Create temp directories to export stuff into
TEMP_DIR_1=`mktemp -d`
TEMP_DIR_2=`mktemp -d`

function unpack_sketch_file {
  IN_FILE="$1"
  OUT_PATH="$2/$BASENAME/"

  SKETCHTOOL="/Applications/Sketch.app/Contents/Resources/sketchtool/bin/sketchtool"

  echo "$BASENAME: Unpacking $3..."

  mkdir -p "$OUT_PATH"
  "$SKETCHTOOL" export artboards "$IN_FILE" \
      --output="$OUT_PATH/artboards" \
      --include-symbols=YES \
      >/dev/null
  "$SKETCHTOOL" export pages "$IN_FILE" \
      --output="$OUT_PATH" \
      --max-size=1000 \
      >/dev/null
}

# Unpack sketch files
unpack_sketch_file "$FILE_1" "$TEMP_DIR_1" "left sketch file"
unpack_sketch_file "$FILE_2" "$TEMP_DIR_2" "right sketch file"

# Kaleidoscope diff on the two paths
ksdiff --partial-changeset -- "$TEMP_DIR_1" "$TEMP_DIR_2"

Hi there - I'm currently trialling Kaleidoscope as a diff tool for sketch but stumbling at the first hurdle (I'm aware of the sketch file format's zip properties and have heard mention of unpacking it to work with GIT) - I stumbled across this GIST from a google search - can you explain what it does please?

Super delayed response! This script unpacks both the previous (left) and new (right) Sketch files using sketchtool (a binary that ships with Sketch) and then compares the two results (which are each directories of png screenshots of artboards)