https://www.google.hu/search?q=sphere&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjJ-rWo4NTSAhUD1iwKHVXcDosQ_AUIBigB&biw=1024&bih=662#tbm=isch&q=transparent+square+png&*
https://timbunce.files.wordpress.com/2009/08/square-gradient-mask.png?w=200&h=200
https://blog.timbunce.org/2009/08/31/can-you-help-me-generate-an-alpha-channel-gradient-image/



http://pngimages.net/sites/default/files/crystal--style-rectangular-button-png-image-2862.png
http://pngimages.net/square-png
