From a0c4815433ccd57322f4f7703ca35e9ccfa59250 Mon Sep 17 00:00:00 2001 From: marha Date: Thu, 8 Oct 2009 13:15:52 +0000 Subject: Added MesaLib-7.6 --- mesalib/src/glu/sgi/libtess/tessmono.c | 201 +++++++++++++++++++++++++++++++++ 1 file changed, 201 insertions(+) create mode 100644 mesalib/src/glu/sgi/libtess/tessmono.c (limited to 'mesalib/src/glu/sgi/libtess/tessmono.c') diff --git a/mesalib/src/glu/sgi/libtess/tessmono.c b/mesalib/src/glu/sgi/libtess/tessmono.c new file mode 100644 index 000000000..4d0844005 --- /dev/null +++ b/mesalib/src/glu/sgi/libtess/tessmono.c @@ -0,0 +1,201 @@ +/* + * 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 +#include "geom.h" +#include "mesh.h" +#include "tessmono.h" +#include + +#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; +} -- cgit v1.2.3