dmeny@polyslo.CalPoly.EDU (David William Meny) (04/27/91)
Hello. This is the first time I've posted a message, and I was unable to
read the help file, so please excuse any errors I make. On to my problem...
I am making a graphics program in C on the Amiga and I want to copy some
customized graphics (i.e., not built using graphics primitives) onto a screen
bitmap. I have been using BltBitMap to copy from a hidden, temporary bitmap
onto which I have loaded an IFF graphics file which I drew in DP III. I have
also used DrawImage to display graphics defined in an array of UWORD.
My problem is that I want the graphics to replace the background (existing)
graphics only where the original graphics uses pens 1 through 31 (in low-res)
or 1-15 (in hi-res). That is, I want any pixel drawn in pen #0 in the graphics
to be moved on to a background to behave as transparent and not be drawn into
the background.
I have experimented with BltBitMap by changing the minterms and mask, and
I have been able to obtain transparency, but not without the alteration of
the graphics' colors (the graphics to be copied is multi-colored). I have
also tried using DrawImage with various PlanePick and PlaneOnOff settings,
which does not even result in any transparency, just color changes.
Does anybody know the fastest (and easiest) way to do what I am trying to
achieve? Any help would be much appreciated!
----> David W. Meny
Again, I apologize for any problems with this message. VI is not working
correctly and this is the first time I've posted a message here. Thanks
again.