This trap sets the graphics fill mode on or off. Once the mode has been set on, all non re-entrant shapes produced thereafter by the graphics traps will be filled with the ink colour until the mode is set off.

A non re-entrant shape is a closed curve such that no horizontal line passes through more than two points of the curve.

• All registers not shown above are not used on entry and are preserved on exit.
• The mode key in D1.L is 0 for off and 1 for on.

The example below shows the use of this trap call to set the fill mode on.

mode    moveq   #1,d1           ; Set mode key to "on"
        moveq   #sd_flood,d0    ; $35
        moveq   #-1,d3          ; Timeout
        trap    #3              ; set the mode on
        tst.l   d0              ; OK? . .
        bne     error           ; . . no!