Icon definition on an atlas image
use_icon_definition(x = 0, y = 0, width = 128, height = 128,
anchorX = (width/2), anchorY = 128, mask = TRUE)
x position of icon on the atlas image
y position of icon on the atlas image
width of icon on the atlas image
height of icon on the atlas image
horizontal position of icon anchor
vertical position of icon anchor
whether icon is treated as a transparency mask,
if TRUE
, user defined color is applied,
if FALSE
, pixel color from the image is applied