Atari ST series Technical Reference Manual page 155

Table 7-4. Line A Variables Used by Seed Fill
Offset Name Offset
CUR__WORK -$64
INTIN
$0C
PTSIN
WMODE $24
PATPTR $2E
$32
PATMSK
$34
MFILL
CLIP $36
XMINCL
$38
YMINCL $3A
XMAXCL $3C
$3E
YMAXCL
SEEDABORT $76
The Seed Fill routine operates quite similarly to its VDI
counterpart. The coordinates for the initial fill point must be
placed in a word array, and a pointer to that array must be
stored in PTSIN. A pointer to a word flag must be placed in
INTIN. If this value is negative, the color fill mode is used. If
it is positive, outline mode is used, and this value is inter­
preted as the VDI color index number of the polygon outline.
You should note that VDI color index numbers are not the
Line A Routines
Description
Pointer to the current virtual workstation
variable table. The VDI fill color index is
the 16th member of this word array.
Pointer to a word array that contains the
x and y coordinates of the initial fill point,
in that order
Pointer to a word value that represents
the VDI color index of the polygon
outline. If this value is negative, color
mode is used instead of outline mode.
Writing mode
Pointer to fill pattern array
Pattern index (length - 1)
Multicolor fill pattern flag (zero = single
plane, nonzero = multiplane)
Clipping flag is ignored by this function.
It always clips to the rectangle described
below, whether this variable is set on or
off.
Coordinate of left side of clip rectangle
Coordinate of top of clip rectangle
Coordinate of right side of clip rectangle
Coordinate of bottom of clip rectangle
Pointer to a routine which is called at the
end of each fill line. If this routine returns
a value of zero in register DO, Seed Fill
continues filling the next scan line. If this
routine return a nonzero value in D O ,
Seed Fill aborts. At minimum, a pointer
to a routine that moves a zero to D O and
then executes an RTS instruction must be
placed in this variable, or Seed Fill will
crash.
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