Remove specified background colour from sprite/spritesheet

main.rb

# cromakey no chromakey
# removes a specified background colour from a spritesheet
# by making it transparent and exports it as a new file.

# change these values then run in DragonRuby

# path to spritesheet
INPUT_FILE = '/sprites/chroma-test-input.png'
# path to export file
OUTPUT_FILE = '/sprites/chroma-test-output.png'
# background color to make transparent
CHROMA_COLOR = {r: 69, g: 114, b: 227}

def tick args
  wh = args.gtk.calcspritebox(INPUT_FILE)

  rect = {
    x: 0, y: 60, 
    w: wh[0], h: wh[1]
  }

  args.outputs.primitives << {
    path: INPUT_FILE
  }.merge(rect).sprite

  return if args.tick_count > 1
  
    args.outputs.screenshots << {
      path: OUTPUT_FILE,
      a: 0
    }.merge(rect).merge(CHROMA_COLOR)
end