Quote Originally Posted by Nitrogen
3. BitBlt the Mask onto the destination with the SRCAND raster constant.
4. BitBlt the original sprite with the SRCPAINT raster operator.
I played around with the old ROPS again (long time since I did this!)
However, I got some serious problems with anything other than SRCCOPY or WHITENESS. Sometimes I even got pieces of my desktop mixed into the screen and only every other flip was updated?
I used the wait bits etc, but still odd behaviour... anyway, I ended up just drawing an inverted mask (more like a stencil really) and this works fine for pre-rendered work.

The problem remains how to generate a mask / stencil from an existing dynamic screen though - but I don't need it now