1 files changed, 74 insertions, 0 deletions
diff --git a/pkg/xtools/icfit/icgnearest.gx b/pkg/xtools/icfit/icgnearest.gx
new file mode 100644
index 00000000..d3165940
--- /dev/null
+++ b/pkg/xtools/icfit/icgnearest.gx
@@ -0,0 +1,74 @@
+# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
+
+include	<mach.h>
+include	<pkg/gtools.h>
+include "icfit.h"
+
+# ICG_NEAREST -- Find the nearest point to the cursor and return the index.
+# The nearest point to the cursor in NDC coordinates is determined.
+# The cursor is moved to the nearest point selected.
+
+int procedure icg_nearest$t (ic, gp, gt, cv, x, y, npts, wx, wy)
+
+pointer	ic					# ICFIT pointer
+pointer	gp					# GIO pointer
+pointer	gt					# GTOOLS pointer
+pointer	cv					# CURFIT pointer
+PIXEL	x[npts], y[npts]			# Data points
+int	npts					# Number of points
+real	wx, wy					# Cursor position
+
+int	pt
+pointer	sp, xout, yout
+
+int	icg_n$t(), gt_geti()
+
+begin
+	call smark (sp)
+	call salloc (xout, npts, TY_PIXEL)
+	call salloc (yout, npts, TY_PIXEL)
+	call icg_axes$t (ic, gt, cv, 1, x, y, Mem$t[xout], npts)
+	call icg_axes$t (ic, gt, cv, 2, x, y, Mem$t[yout], npts)
+	if (gt_geti (gt, GTTRANSPOSE) == NO)
+	    pt = icg_n$t (gp, Mem$t[xout], Mem$t[yout], npts, wx, wy)
+	else
+	    pt = icg_n$t (gp, Mem$t[yout], Mem$t[xout], npts, wy, wx)
+	call sfree (sp)
+	
+	return (pt)
+end
+
+int procedure icg_n$t (gp, x, y, npts, wx, wy)
+
+pointer	gp					# GIO pointer
+PIXEL	x[npts], y[npts]			# Data points
+int	npts					# Number of points
+real	wx, wy					# Cursor position
+
+int	i, j
+real	x0, y0, r2, r2min
+
+begin
+	# Transform world cursor coordinates to NDC.
+
+	call gctran (gp, wx, wy, wx, wy, 1, 0)
+
+	# Search for nearest point.
+
+	r2min = MAX_REAL
+	do i = 1, npts {
+	    call gctran (gp, real (x[i]), real (y[i]), x0, y0, 1, 0)
+	    r2 = (x0 - wx) ** 2 + (y0 - wy) ** 2
+	    if (r2 < r2min) {
+		r2min = r2
+		j = i
+	    }
+	}
+
+	# Move the cursor to the selected point and return the index.
+
+	if (j != 0)
+	    call gscur (gp, real (x[j]), real (y[j]))
+
+	return (j)
+end