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include <gset.h>
include <mach.h>
include "sensfunc.h"
# SF_NEAREST -- Find the nearest point to the cursor. Return the standard
# star index and the wavelength point index. The metric is in NDC.
# The cursor is moved to the nearest point selected. Return zero for
# the standard star index if valid point not found.
procedure sf_nearest (gp, stds, nstds, wx, wy, wcs, type, istd, ipt)
pointer gp # Graphics pointer
pointer stds[nstds] # Standard star data
int nstds # Number of standard stars
real wx, wy # Cursor position
int wcs # WCS
int type # Type of points (0=not del, 1=del, 2=both)
int istd # Index of standard star (returned)
int ipt # Index of point (returned)
int i, j, n, stridx()
real x0, y0, x1, y1, x2, y2, r2, r2min
pointer x, y, w, gio
begin
# Check for valid wc.
istd = 0
if (stridx (GP_GRAPHS(gp,wcs), "ars") == 0)
return
# Transform world cursor coordinates to NDC.
gio = GP_GIO(gp)
call gctran (gio, wx, wy, wx, wy, wcs, 0)
# Search for nearest point.
r2min = MAX_REAL
do i = 1, nstds {
if (STD_FLAG(stds[i]) != SF_INCLUDE)
next
n = STD_NWAVES(stds[i])
x = STD_X(stds[i]) - 1
y = STD_Y(stds[i]) - 1
w = STD_WTS(stds[i]) - 1
do j = 1, n {
if (type == 0) {
if (Memr[w+j] == 0.)
next
} else if (type == 1) {
if (Memr[w+j] != 0.)
next
}
x1 = Memr[x+j]
y1 = Memr[y+j]
call gctran (gio, x1, y1, x0, y0, wcs, 0)
r2 = (x0 - wx) ** 2 + (y0 - wy) ** 2
if (r2 < r2min) {
r2min = r2
istd = i
ipt = j
x2 = x1
y2 = y1
}
}
}
# Move the cursor to the selected point.
call gseti (gio, G_WCS, wcs)
call gscur (gio, x2, y2)
end
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