There's functions in the archives for changing the masked/alphaed texel. It's not dependant on colour, which is good :)
http://www.blitzbasic.com/codearcs/codearcs.php?code=1013
But, check out jfk's link too:
http://www.blitzbasic.com/codearcs/codearcs.php?code=795
I think that is more useful to you :o)
http://www.blitzbasic.com/codearcs/codearcs.php?code=1013
But, check out jfk's link too:
http://www.blitzbasic.com/codearcs/codearcs.php?code=795
I think that is more useful to you :o)