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1 files changed, 40 insertions, 0 deletions

diff --git a/noao/nproto/ir/iroverlap.x b/noao/nproto/ir/iroverlap.x
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+++ b/noao/nproto/ir/iroverlap.x
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+# IR_OVERLAP -- Procedure to compute the overlap between two rectangles.
+
+int procedure ir_overlap (pc1out, pc2out, pl1out, pl2out, c1out, c2out,
+	l1out, l2out, oc1out, oc2out, ol1out, ol2out)
+
+int	pc1out, pc2out		# previous subraster column limits
+int	pl1out, pl2out		# previous subraster line limits
+int	c1out, c2out		# current subraster column limits
+int	l1out, l2out		# current subraster line limits
+int	oc1out, oc2out		# overlap column limits
+int	ol1out, ol2out		# overlap line limits
+
+begin
+	# Check for the case where no intersection is present.
+	if (c1out > pc2out || c2out < pc1out || l1out > pl2out ||
+	    l2out < pl1out)
+	    return (NO)
+
+	# Compute the column overlap limits.
+	if (pc1out <= c1out)
+	    oc1out = c1out
+	else
+	    oc1out = pc1out
+	if (pc2out <= c2out)
+	    oc2out = pc2out
+	else
+	    oc2out = c2out
+
+	# Compute the line overlap limits.
+	if (pl1out <= l1out)
+	    ol1out = l1out
+	else
+	    ol1out = pl1out
+	if (pl2out <= l2out)
+	    ol2out = pl2out
+	else
+	    ol2out = l2out
+
+	return (YES)
+end