From 7dfcc480ba1e19bd3232349fc733caef94034292 Mon Sep 17 00:00:00 2001
From: stainer_t <thomas.stainer@oecd-nea.org>
Date: Mon, 8 Sep 2025 13:48:49 +0200
Subject: Initial commit from Polytechnique Montreal

---
 Dragon/src/NXTPRR.f | 81 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 81 insertions(+)
 create mode 100644 Dragon/src/NXTPRR.f

(limited to 'Dragon/src/NXTPRR.f')

diff --git a/Dragon/src/NXTPRR.f b/Dragon/src/NXTPRR.f
new file mode 100644
index 0000000..06fb2f2
--- /dev/null
+++ b/Dragon/src/NXTPRR.f
@@ -0,0 +1,81 @@
+*DECK NXTPRR
+      FUNCTION NXTPRR(XYREC1,XYREC2,XYRECI)
+*
+*----------
+*
+*Purpose:
+* Find the rectangle representing the intersection of two rectangles.
+*
+*Copyright:
+* Copyright (C) 2005 Ecole Polytechnique de Montreal
+* This library is free software; you can redistribute it and/or
+* modify it under the terms of the GNU Lesser General Public
+* License as published by the Free Software Foundation; either
+* version 2.1 of the License, or (at your option) any later version.
+*
+*Author(s): G. Marleau.
+*
+*Parameters: input
+* XYREC1  spatial description of the first rectangle with:
+*         XYREC1(1) for left face; XYREC1(2) for right face;
+*         XYREC1(3) for bottom face; XYREC1(4) for top face
+*         positions.
+* XYREC2  spatial description of the second rectangle with:
+*         XYREC2(1) for left face; XYREC2(2) for right face;
+*         XYREC2(3) for bottom face; XYREC2(4) for top face
+*         positions.
+*Parameters: output
+* NXTPRR  type of intersection between rectangles where
+*         =0 means that there is no intersection
+*         between the two regions;
+*         =1 means that there is an intersection between
+*         between the two regions.
+* XYRECI  spatial description of the intersection rectangle with:
+*         XYRECI(1) for left face; XYRECI(2) for right face;
+*         XYRECI(3) for bottom face; XYRECI(4) for top face
+*         positions.
+*
+*Reference:
+*  G. Marleau,
+*  New Geometries Processing in DRAGON: The NXT: Module,
+*  Report IGE-260, Polytechnique Montreal,
+*  Montreal, 2005.
+*
+*----------
+*
+      IMPLICIT         NONE
+*----
+*  Subroutine arguments
+*----
+      INTEGER          NXTPRR
+      DOUBLE PRECISION XYREC1(4),XYREC2(4)
+      DOUBLE PRECISION XYRECI(4)
+*----
+*  Local parameters
+*----
+      INTEGER          IOUT
+      CHARACTER        NAMSBR*6
+      PARAMETER       (IOUT=6,NAMSBR='NXTPRR')
+*----
+*  Local variables
+*----
+      INTEGER          IFACE
+*----
+*  Find position of surface of intersection
+*  -> for left and bottom faces, maximum $X$ and $Y$ location.
+*  -> for right and top faces, minimum $X$ and $Y$ location.
+*----
+      NXTPRR=1
+      DO 100 IFACE=1,3,2
+        XYRECI(IFACE)=MAX(XYREC2(IFACE),XYREC1(IFACE))
+ 100  CONTINUE
+      DO 101 IFACE=2,4,2
+        XYRECI(IFACE)=MIN(XYREC2(IFACE),XYREC1(IFACE))
+ 101  CONTINUE
+*----
+*  Test if intersection is valid
+*----
+      IF(XYRECI(1) .GE. XYRECI(2) .OR.
+     >   XYRECI(3) .GE. XYRECI(4)) NXTPRR=0
+      RETURN
+      END
-- 
cgit v1.2.3