[comp.sys.atari.st.tech] Mouse pointer clipping help please

erik@mcrware.UUCP (Erik Johnson) (01/23/91)

I have a program that runs in low resolution (even though you might load
it from medium res), but I am having problems with the cursor.

Right now, to keep the mouse pointer from wrapping around twice when you move
all the way to the right side, I intercept the cursor movement vector so that
the cursor can not move beyond 319 in the x direction.  This works fine,
except that when the cursor is near the right edge of the screen, the image
wraps to the left side of the screen slightly.  This does not affect the 
function of the mouse but it is slightly annoying.

What I need is a way to tell the machine that the screen is 320 pixels wide,
not 640, so treat the mouse accordingly.  By a little investigation, I have
found a memory location to do just this, but no doubt use of it directly
would be "illeal" and may not work on other machines.

Any help would be much appreciated.

Thank you,

Erik R Johnson      erik@mcrware.com