Quote: ""Image masking""
Have a look at the corona sdk has a good example of image masking.
But basically the ability to set a different image as an additional alpha channel layer for a sprite.
image = LoadImage ( "someImage.png" )
mask = LoadImage ( "someMask.png" ) // Greyscale ideally
sprite = CreateSprite ( image )
// associate a mask with the sprite
// the mask will act like an alpha channel overlay that masks out parts of the image not associated with the mask area
setSpriteMask( sprite, mask )
// scale the mask relative to the sprite
setSpriteMaskScale( sprite , u , v )
// adjust the position of the mask relative to the image
setSpriteMaskOffset( sprite , x , y )
// determine if the mask tiles / wraps
setSpriteMaskWrapping( sprite , TileYesNo , WrapYesNo )
Westa
