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authormarha <marha@users.sourceforge.net>2012-09-03 09:54:39 +0200
committermarha <marha@users.sourceforge.net>2012-09-04 14:23:32 +0200
commitc18d12d1e36354ff32724c86ae25374d1a78607f (patch)
tree3db58d40725863f1d1145002f998a6cf0662fbf9 /mesalib/src/glu/sgi/libtess/tessmono.c
parent77f54d0b20cc194e708bc664740e4c0b0e13c3dd (diff)
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mesa xkeyboard-config git update 3 sep 2012
Diffstat (limited to 'mesalib/src/glu/sgi/libtess/tessmono.c')
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diff --git a/mesalib/src/glu/sgi/libtess/tessmono.c b/mesalib/src/glu/sgi/libtess/tessmono.c
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-/*
- * SGI FREE SOFTWARE LICENSE B (Version 2.0, Sept. 18, 2008)
- * Copyright (C) 1991-2000 Silicon Graphics, Inc. All Rights Reserved.
- *
- * Permission is hereby granted, free of charge, to any person obtaining a
- * copy of this software and associated documentation files (the "Software"),
- * to deal in the Software without restriction, including without limitation
- * the rights to use, copy, modify, merge, publish, distribute, sublicense,
- * and/or sell copies of the Software, and to permit persons to whom the
- * Software is furnished to do so, subject to the following conditions:
- *
- * The above copyright notice including the dates of first publication and
- * either this permission notice or a reference to
- * http://oss.sgi.com/projects/FreeB/
- * shall be included in all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
- * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
- * SILICON GRAPHICS, INC. BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
- * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF
- * OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
- * SOFTWARE.
- *
- * Except as contained in this notice, the name of Silicon Graphics, Inc.
- * shall not be used in advertising or otherwise to promote the sale, use or
- * other dealings in this Software without prior written authorization from
- * Silicon Graphics, Inc.
- */
-/*
-** Author: Eric Veach, July 1994.
-**
-*/
-
-#include "gluos.h"
-#include <stdlib.h>
-#include "geom.h"
-#include "mesh.h"
-#include "tessmono.h"
-#include <assert.h>
-
-#define AddWinding(eDst,eSrc) (eDst->winding += eSrc->winding, \
- eDst->Sym->winding += eSrc->Sym->winding)
-
-/* __gl_meshTessellateMonoRegion( face ) tessellates a monotone region
- * (what else would it do??) The region must consist of a single
- * loop of half-edges (see mesh.h) oriented CCW. "Monotone" in this
- * case means that any vertical line intersects the interior of the
- * region in a single interval.
- *
- * Tessellation consists of adding interior edges (actually pairs of
- * half-edges), to split the region into non-overlapping triangles.
- *
- * The basic idea is explained in Preparata and Shamos (which I don''t
- * have handy right now), although their implementation is more
- * complicated than this one. The are two edge chains, an upper chain
- * and a lower chain. We process all vertices from both chains in order,
- * from right to left.
- *
- * The algorithm ensures that the following invariant holds after each
- * vertex is processed: the untessellated region consists of two
- * chains, where one chain (say the upper) is a single edge, and
- * the other chain is concave. The left vertex of the single edge
- * is always to the left of all vertices in the concave chain.
- *
- * Each step consists of adding the rightmost unprocessed vertex to one
- * of the two chains, and forming a fan of triangles from the rightmost
- * of two chain endpoints. Determining whether we can add each triangle
- * to the fan is a simple orientation test. By making the fan as large
- * as possible, we restore the invariant (check it yourself).
- */
-int __gl_meshTessellateMonoRegion( GLUface *face )
-{
- GLUhalfEdge *up, *lo;
-
- /* All edges are oriented CCW around the boundary of the region.
- * First, find the half-edge whose origin vertex is rightmost.
- * Since the sweep goes from left to right, face->anEdge should
- * be close to the edge we want.
- */
- up = face->anEdge;
- assert( up->Lnext != up && up->Lnext->Lnext != up );
-
- for( ; VertLeq( up->Dst, up->Org ); up = up->Lprev )
- ;
- for( ; VertLeq( up->Org, up->Dst ); up = up->Lnext )
- ;
- lo = up->Lprev;
-
- while( up->Lnext != lo ) {
- if( VertLeq( up->Dst, lo->Org )) {
- /* up->Dst is on the left. It is safe to form triangles from lo->Org.
- * The EdgeGoesLeft test guarantees progress even when some triangles
- * are CW, given that the upper and lower chains are truly monotone.
- */
- while( lo->Lnext != up && (EdgeGoesLeft( lo->Lnext )
- || EdgeSign( lo->Org, lo->Dst, lo->Lnext->Dst ) <= 0 )) {
- GLUhalfEdge *tempHalfEdge= __gl_meshConnect( lo->Lnext, lo );
- if (tempHalfEdge == NULL) return 0;
- lo = tempHalfEdge->Sym;
- }
- lo = lo->Lprev;
- } else {
- /* lo->Org is on the left. We can make CCW triangles from up->Dst. */
- while( lo->Lnext != up && (EdgeGoesRight( up->Lprev )
- || EdgeSign( up->Dst, up->Org, up->Lprev->Org ) >= 0 )) {
- GLUhalfEdge *tempHalfEdge= __gl_meshConnect( up, up->Lprev );
- if (tempHalfEdge == NULL) return 0;
- up = tempHalfEdge->Sym;
- }
- up = up->Lnext;
- }
- }
-
- /* Now lo->Org == up->Dst == the leftmost vertex. The remaining region
- * can be tessellated in a fan from this leftmost vertex.
- */
- assert( lo->Lnext != up );
- while( lo->Lnext->Lnext != up ) {
- GLUhalfEdge *tempHalfEdge= __gl_meshConnect( lo->Lnext, lo );
- if (tempHalfEdge == NULL) return 0;
- lo = tempHalfEdge->Sym;
- }
-
- return 1;
-}
-
-
-/* __gl_meshTessellateInterior( mesh ) tessellates each region of
- * the mesh which is marked "inside" the polygon. Each such region
- * must be monotone.
- */
-int __gl_meshTessellateInterior( GLUmesh *mesh )
-{
- GLUface *f, *next;
-
- /*LINTED*/
- for( f = mesh->fHead.next; f != &mesh->fHead; f = next ) {
- /* Make sure we don''t try to tessellate the new triangles. */
- next = f->next;
- if( f->inside ) {
- if ( !__gl_meshTessellateMonoRegion( f ) ) return 0;
- }
- }
-
- return 1;
-}
-
-
-/* __gl_meshDiscardExterior( mesh ) zaps (ie. sets to NULL) all faces
- * which are not marked "inside" the polygon. Since further mesh operations
- * on NULL faces are not allowed, the main purpose is to clean up the
- * mesh so that exterior loops are not represented in the data structure.
- */
-void __gl_meshDiscardExterior( GLUmesh *mesh )
-{
- GLUface *f, *next;
-
- /*LINTED*/
- for( f = mesh->fHead.next; f != &mesh->fHead; f = next ) {
- /* Since f will be destroyed, save its next pointer. */
- next = f->next;
- if( ! f->inside ) {
- __gl_meshZapFace( f );
- }
- }
-}
-
-#define MARKED_FOR_DELETION 0x7fffffff
-
-/* __gl_meshSetWindingNumber( mesh, value, keepOnlyBoundary ) resets the
- * winding numbers on all edges so that regions marked "inside" the
- * polygon have a winding number of "value", and regions outside
- * have a winding number of 0.
- *
- * If keepOnlyBoundary is TRUE, it also deletes all edges which do not
- * separate an interior region from an exterior one.
- */
-int __gl_meshSetWindingNumber( GLUmesh *mesh, int value,
- GLboolean keepOnlyBoundary )
-{
- GLUhalfEdge *e, *eNext;
-
- for( e = mesh->eHead.next; e != &mesh->eHead; e = eNext ) {
- eNext = e->next;
- if( e->Rface->inside != e->Lface->inside ) {
-
- /* This is a boundary edge (one side is interior, one is exterior). */
- e->winding = (e->Lface->inside) ? value : -value;
- } else {
-
- /* Both regions are interior, or both are exterior. */
- if( ! keepOnlyBoundary ) {
- e->winding = 0;
- } else {
- if ( !__gl_meshDelete( e ) ) return 0;
- }
- }
- }
- return 1;
-}