SGI SI GLU library

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+/*
+** License Applicability. Except to the extent portions of this file are
+** made subject to an alternative license as permitted in the SGI Free
+** Software License B, Version 1.1 (the "License"), the contents of this
+** file are subject only to the provisions of the License. You may not use
+** this file except in compliance with the License. You may obtain a copy
+** of the License at Silicon Graphics, Inc., attn: Legal Services, 1600
+** Amphitheatre Parkway, Mountain View, CA 94043-1351, or at:
+** 
+** http://oss.sgi.com/projects/FreeB
+** 
+** Note that, as provided in the License, the Software is distributed on an
+** "AS IS" basis, with ALL EXPRESS AND IMPLIED WARRANTIES AND CONDITIONS
+** DISCLAIMED, INCLUDING, WITHOUT LIMITATION, ANY IMPLIED WARRANTIES AND
+** CONDITIONS OF MERCHANTABILITY, SATISFACTORY QUALITY, FITNESS FOR A
+** PARTICULAR PURPOSE, AND NON-INFRINGEMENT.
+** 
+** Original Code. The Original Code is: OpenGL Sample Implementation,
+** Version 1.2.1, released January 26, 2000, developed by Silicon Graphics,
+** Inc. The Original Code is Copyright (c) 1991-2000 Silicon Graphics, Inc.
+** Copyright in any portions created by third parties is as indicated
+** elsewhere herein. All Rights Reserved.
+** 
+** Additional Notice Provisions: The application programming interfaces
+** established by SGI in conjunction with the Original Code are The
+** OpenGL(R) Graphics System: A Specification (Version 1.2.1), released
+** April 1, 1999; The OpenGL(R) Graphics System Utility Library (Version
+** 1.3), released November 4, 1998; and OpenGL(R) Graphics with the X
+** Window System(R) (Version 1.3), released October 19, 1998. This software
+** was created using the OpenGL(R) version 1.2.1 Sample Implementation
+** published by SGI, but has not been independently verified as being
+** compliant with the OpenGL(R) version 1.2.1 Specification.
+**
+** $Date: 2001/03/17 00:25:41 $ $Revision: 1.1 $
+*/
+/*
+ *partitionY.h:
+ *partition a polygon into a Y-monotone polygon:
+ * A polygon is Y-monotone if the boundary can be split into two polygon chains
+ *A and B such that each chain is Y-monotonic that is the intersection of any
+ *horizontal line intersects each chain has at most one connected componenets
+ * (empty, single point or a single line).
+ * 
+ * A vertex is a cusp if both its ajacent vertices are either at or above v, 
+ *or both at or below v. In addition, at least one of the ajacent verteces is
+ *strictly below or above v. 
+ * A vertex is a relex vertex if the internals angle is strictly greater than 
+ *180. In other words, if the the signed area is negative:
+ *(x1, y1), (x2, y2), (x3, y3) are the three vertices along a polygon, the 
+ *order is such that left hand side is inside the polygon. Then (x2,y2) is
+ *reflex if: 
+ *  (x2-x1, y2-y1) cross (x3-x1, y3-y1) <0.
+ *A vertex is an interior cusp if it is a cusp and a reflex.
+ *A vertex is an exterior cusp if it is a cusp but not a reflex.
+ *
+ * $Header: /home/krh/git/sync/mesa-cvs-repo/Mesa/src/glu/sgi/libnurbs/nurbtess/partitionY.h,v 1.1 2001/03/17 00:25:41 brianp Exp $
+ */
+
+#ifndef _PARTITIONY_H
+#define _PARTITIONY_H
+
+#include "directedLine.h"
+
+/*whether an edge is below a vertex*/
+Int isBelow(directedLine *v, directedLine *e);
+
+/*whether an edge is above a vertex*/
+Int isAbove(directedLine *v, directedLine *e);
+
+/*not-cusp,
+ *inerior cusp
+ *exterior cusp
+ */
+Int cuspType(directedLine *v);
+
+/*used in trapezoidalization*/
+typedef struct sweepRange{
+  directedLine *left;
+  Int leftType; /*either a vertex (leftType=0) or an edge (leftType =1) */
+  directedLine *right;
+  Int rightType; /*either a vertex (rightType=0) or an edge (rightType =1) */  
+} sweepRange;
+
+sweepRange* sweepRangeMake(directedLine* left, Int leftType,
+			   directedLine* right, Int rightType);
+
+void sweepRangeDelete(sweepRange* range);
+Int sweepRangeEqual(sweepRange* sr1, sweepRange* sr2);
+
+/*given a set of simple polygons where the interior 
+ *is decided by left-hand principle,
+ *return a range (sight) for each vertex. This is called
+ *Trapezoidalization.
+ */
+void sweepY(Int nVertices, directedLine **sortedVerteces, sweepRange** ret_ranges);
+
+
+directedLine* partitionY(directedLine *polygons, sampledLine **retSampledLines);
+
+void findDiagonals(Int total_num_edges, directedLine** sortedVertices, sweepRange** ranges, Int& num_diagonals, directedLine** diagonal_vertices);
+
+directedLine** DBGfindDiagonals(directedLine *polygons, Int& num_diagonals);
+
+#endif