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# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
include <math.h>
include <plset.h>
include <plio.h>
# PL_LINE -- Perform a rasterop operation upon a line of arbitrary width drawn
# at an arbitrary orientation 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_line (pl, x1, y1, x2, y2, width, rop)
pointer pl #I mask descriptor
int x1,y1 #I start point of line
int x2,y2 #I end point of line
int width #I width of line to be drawn, pixels
int rop #I rasterop defining operation
int npts
int x[4], y[4]
real theta, hwidth, dx, dy
begin
dx = x2 - x1
dy = y2 - y1
# Compute the line direction and halfwidth.
hwidth = max (1.0, real(width)) / 2.0 - 0.001
if (abs(dx) < 0.0001) {
if (dy > 0)
theta = HALFPI
else
theta = -HALFPI
} else if (abs(dy) < 0.0001) {
if (dx > 0)
theta = 0.0
else
theta = PI
} else
theta = atan2 (dy, dx)
# Construct a polyline to be filled to draw the line.
if (width < 1.0001) {
x[1] = x1; y[1] = y1
x[2] = x2; y[2] = y2
npts = 2
} else {
x[1] = x1 + nint (hwidth * cos(theta+HALFPI))
y[1] = y1 + nint (hwidth * sin(theta+HALFPI))
x[2] = x1 + nint (hwidth * cos(theta-HALFPI))
y[2] = y1 + nint (hwidth * sin(theta-HALFPI))
x[3] = x2 + nint (hwidth * cos(theta-HALFPI))
y[3] = y2 + nint (hwidth * sin(theta-HALFPI))
x[4] = x2 + nint (hwidth * cos(theta+HALFPI))
y[4] = y2 + nint (hwidth * sin(theta+HALFPI))
npts = 4
}
# Draw the line.
call pl_polygon (pl, x, y, npts, rop)
end
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