Then, it will take a lot of time and explanation (and I have no idea how to make it without a "framework" ).
Anyway, the work is the same in any case:
- Keep two bit-maps that contains the foreground and the background.
- Upload them and use the "foreground" to hide the "background", but don't remove them from "system" memory.
- Now, as user moves the mouse, make "foreground" bitmap pixels transparent and upload it, substituting the old foreground (i.e., use the same GL ID).
- Repeat.
Bookmarks