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# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
include <math.h>
include "ccp.h"
define DIAGSEP (g_plwsep / 0.8660254) # distance to vertex of hexagon
define PIOVER3 (PI / 3.0)
define PIOVER6 (PI / 6.0)
define SIN_MIN_HALFBISECTOR 0.1 # sine of minimum half-bisector
# CCP_DRAWSEG -- Draw a polyline segment, optionally simulating variable
# widths.
procedure ccp_drawseg (xseg, yseg, nsegpts, lwidth)
real xseg[ARB] # plotter coordinate array of contiguous points
real yseg[ARB]
int nsegpts # number of pts in array
int lwidth # line width relative to single width
int i, j
real pleft_x[MAXTRACES], pleft_y[MAXTRACES]
real pright_x[MAXTRACES], pright_y[MAXTRACES], lastp_x,lastp_y
real ahp2p1, theta, delx,dely, dx,dy, tx,ty
real rptheta4 ()
include "ccp.com"
data lastp_x/0.0/, lastp_y/0.0/
begin
if (nsegpts < 1)
return
if (lwidth > MAXTRACES) {
call eprintf ("WARNING: line width > MAXTRACES in ccp_drawseg\n")
call eprintf (" line width reset to %d\n")
call pargi (MAXTRACES)
lwidth = MAXTRACES
}
if (nsegpts == 1) { # 1 pt spcl bold
# Draw a single point as a hexagon lined up in the direction from
# the preceding point. Start bounding hexagon 60 degrees cc from
# projection of last point drawn (0,0 initially) through current pt.
# 'ahp2p1' = Angle from Horizontal at P1 to line P1 -> P2, etc.
ahp2p1 = rptheta4 (xseg[1], yseg[1], lastp_x, lastp_y)
lastp_x = xseg[1]
lastp_y = yseg[1]
theta = ahp2p1 - PIOVER6
# do even a single, interior point as a hexagon, up to lwidth times
do i = 1, lwidth {
tx = xseg[1] + (2 + i) * DIAGSEP * cos (theta)
ty = yseg[1] + (2 + i) * DIAGSEP * sin (theta)
call plot (tx, ty, CCP_UP)
# draw a bounding hexagon around point:
do j = 1, 6 {
theta = theta + PIOVER3
tx = xseg[1] + (2 + i) * DIAGSEP * cos (theta)
ty = yseg[1] + (2 + i) * DIAGSEP * sin (theta)
call plot (tx, ty, CCP_DOWN)
# Store maximum-x plotted for a "newframe" in ccp_clear.
g_max_x = max (tx, g_max_x)
}
# fill in a diagonal line across hexagon:
tx = xseg[1] + (2 + i) * DIAGSEP * cos (theta + PI)
ty = yseg[1] + (2 + i) * DIAGSEP * sin (theta + PI)
call plot (tx, ty, CCP_DOWN)
theta = theta + PIOVER3 # rotate spokes
}
} else { # nsegpts > 1
if (g_lwover || lwidth == PL_SINGLE) {
call plot (xseg[1], yseg[1], CCP_UP)
g_max_x = max (xseg[1], g_max_x)
do i = 2, nsegpts {
call plot (xseg[i], yseg[i], CCP_DOWN)
g_max_x = max (xseg[i], g_max_x)
}
} else if (lwidth > PL_SINGLE) {
# compute flanking points; by definition +-90 deg. from p1-p2,
# so first point is special case; do for all thicknesses:
call ccx_offsets (xseg[1]-xseg[2]+xseg[1],
yseg[1]-yseg[2]+yseg[1], xseg[1],yseg[1],
xseg[2],yseg[2], delx,dely)
do i = 1, lwidth - 1 {
pleft_x[i] = xseg[1] + i * delx
pleft_y[i] = yseg[1] + i * dely
pright_x[i] = xseg[1] - i * delx
pright_y[i] = yseg[1] - i * dely
}
# must draw each segment individually, to make flanks meet.
do i = 1, nsegpts - 2 {
# actual line segment in data:
call plot (xseg[i], yseg[i], CCP_UP)
call plot (xseg[i+1], yseg[i+1], CCP_DOWN)
g_max_x = max (xseg[i], g_max_x)
call ccx_offsets (xseg[i],yseg[i], xseg[i+1],yseg[i+1],
xseg[i+2],yseg[i+2], delx,dely)
# for each flanking line; p2 in middle, at temp origin
do j = 1, lwidth - 1 {
# point to left of p1-p2, facing p2:
dx = j * delx
dy = j * dely
tx = xseg[i+1] + dx
ty = yseg[i+1] + dy
call plot (pleft_x[j], pleft_y[j], CCP_UP)
call plot (tx, ty, CCP_DOWN)
pleft_x[j] = tx
pleft_y[j] = ty
# point to right of p1-p2, facing p2:
tx = xseg[i+1] - dx
ty = yseg[i+1] - dy
call plot (pright_x[j], pright_y[j], CCP_UP)
call plot (tx, ty, CCP_DOWN)
pright_x[j] = tx
pright_y[j] = ty
}
}
# last point:
call plot (xseg[nsegpts-1], yseg[nsegpts-1], CCP_UP)
call plot (xseg[nsegpts], yseg[nsegpts], CCP_DOWN)
g_max_x = max (xseg[nsegpts-1], g_max_x)
g_max_x = max (xseg[nsegpts], g_max_x)
# save this point for a possible following dotted line segment:
lastp_x = xseg[nsegpts]
lastp_y = yseg[nsegpts]
# square the flanking lines:
call ccx_offsets (xseg[nsegpts-1], yseg[nsegpts-1],
xseg[nsegpts], yseg[nsegpts],
xseg[nsegpts] * 2.0 - xseg[nsegpts-1],
yseg[nsegpts] * 2.0 - yseg[nsegpts-1],
delx, dely)
do i = 1, lwidth - 1 {
tx = xseg[nsegpts] + i * delx
ty = yseg[nsegpts] + i * dely
call plot (pleft_x[i], pleft_y[i], CCP_UP)
call plot (tx, ty, CCP_DOWN)
tx = xseg[nsegpts] - i * delx
ty = yseg[nsegpts] - i * dely
call plot (pright_x[i], pright_y[i], CCP_UP)
call plot (tx, ty, CCP_DOWN)
}
}
}
end
# CCX_OFFSETS -- return offsets in x, y from point 2 to one level of line width
# simulation, given points 1, 2, 3.
procedure ccx_offsets (p1x,p1y, p2x,p2y, p3x,p3y, delx,dely)
real p1x,p1y # input: point 1 is previous point
real p2x,p2y # input: point 2 is current point (middle of the three)
real p3x,p3y # input: point 3 is succeeding point
real delx,dely # output: offsets from point 2 to one flanking point
real ahp2p1 # Angle from Horizontal to line p2-->p1, etc.
real ahp2p3, ap1p2p3, ahbisector, sintheta, r
real rptheta4 ()
include "ccp.com"
begin
# convention is that p2 is current point, at temporary origin; p1
# is "behind", and p3 is "ahead" of the current point, p2.
# "ahp2p1" = angle from horizontal to segment p2->p1
# "ap1p2p3" = angle from p1 to p2 to p3
# "ahbisector" = angle from horizontal (+x) to bisector of p1->p2->p3
ahp2p1 = rptheta4 (p2x,p2y, p1x,p1y)
ahp2p3 = rptheta4 (p2x,p2y, p3x,p3y)
ap1p2p3 = ahp2p1 - ahp2p3
ahbisector = ahp2p3 + 0.5 * ap1p2p3
sintheta = sin (ahp2p1 - ahbisector)
# very small angles cause extremely exaggerated vertices; truncate
# at arbitrary multiple of plwsep; 10*plwsep is eqv. to 11.5 deg. bisect
if (abs (sintheta) < SIN_MIN_HALFBISECTOR) {
r = g_plwsep / SIN_MIN_HALFBISECTOR
if (sintheta < 0.0)
r = -r
} else
r = g_plwsep / sintheta
delx = r * cos (ahbisector)
dely = r * sin (ahbisector)
end
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