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# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
include <plset.h>
include <plio.h>
include "plpolygon.h"
# PL_POLYGON -- Perform a rasterop operation on the area enclosed by a polygon
# drawn in a 2-dimensional plane of a mask. If the dimensionality of the mask
# exceeds 2, the pl_setplane() procedure should be called first to define the
# plane of the mask to be modified.
procedure pl_polygon (pl, x, y, npts, rop)
pointer pl #I mask descriptor
int x[npts] #I polygon x-vertices
int y[npts] #I polygon y-vertices
int npts #I number of points in polygon
int rop #I rasterop defining operation
int line_1, line_2, i
pointer sp, ufd, xp, yp, oo
extern pl_upolygon()
errchk plvalid
begin
call plvalid (pl)
if (npts <= 0)
return
else if (npts == 1) {
call pl_point (pl, x[1], y[1], rop)
return
}
call smark (sp)
call salloc (ufd, LEN_PGONDES, TY_STRUCT)
call salloc (oo, RL_FIRST + (npts+1)*3, TY_INT)
call salloc (xp, npts + 1, TY_REAL)
call salloc (yp, npts + 1, TY_REAL)
# Initialize the region descriptor.
P_PL(ufd) = pl
P_XP(ufd) = xp
P_YP(ufd) = yp
P_PV(ufd) = 1
P_OO(ufd) = oo
P_OY(ufd) = -1
P_NS(ufd) = npts - 1
RLI_LEN(oo) = 0
# Copy the user supplied polygon vertices into the descriptor,
# normalizing the polygon in the process.
do i = 1, npts {
Memr[xp+i-1] = x[i]
Memr[yp+i-1] = y[i]
}
if (npts > 2)
if (abs(x[1]-x[npts]) > TOL || abs(y[1]-y[npts]) > TOL) {
Memr[xp+npts] = x[1]
Memr[yp+npts] = y[1]
P_NS(ufd) = npts
}
# Compute the range in Y in which the polygon should be drawn.
call alimi (y, npts, line_1, line_2)
call pl_regionrop (pl, pl_upolygon, ufd, line_1, line_2, rop)
call sfree (sp)
end
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