workbench/libs/mesa/src/glu/sgi/libnurbs/nurbtess/partitionX.cc

   1 /*
   2 ** License Applicability. Except to the extent portions of this file are
   3 ** made subject to an alternative license as permitted in the SGI Free
   4 ** Software License B, Version 1.1 (the "License"), the contents of this
   5 ** file are subject only to the provisions of the License. You may not use
   6 ** this file except in compliance with the License. You may obtain a copy
   7 ** of the License at Silicon Graphics, Inc., attn: Legal Services, 1600
   8 ** Amphitheatre Parkway, Mountain View, CA 94043-1351, or at:
   9 **
  10 ** http://oss.sgi.com/projects/FreeB
  11 **
  12 ** Note that, as provided in the License, the Software is distributed on an
  13 ** "AS IS" basis, with ALL EXPRESS AND IMPLIED WARRANTIES AND CONDITIONS
  14 ** DISCLAIMED, INCLUDING, WITHOUT LIMITATION, ANY IMPLIED WARRANTIES AND
  15 ** CONDITIONS OF MERCHANTABILITY, SATISFACTORY QUALITY, FITNESS FOR A
  16 ** PARTICULAR PURPOSE, AND NON-INFRINGEMENT.
  17 **
  18 ** Original Code. The Original Code is: OpenGL Sample Implementation,
  19 ** Version 1.2.1, released January 26, 2000, developed by Silicon Graphics,
  20 ** Inc. The Original Code is Copyright (c) 1991-2000 Silicon Graphics, Inc.
  21 ** Copyright in any portions created by third parties is as indicated
  22 ** elsewhere herein. All Rights Reserved.
  23 **
  24 ** Additional Notice Provisions: The application programming interfaces
  25 ** established by SGI in conjunction with the Original Code are The
  26 ** OpenGL(R) Graphics System: A Specification (Version 1.2.1), released
  27 ** April 1, 1999; The OpenGL(R) Graphics System Utility Library (Version
  28 ** 1.3), released November 4, 1998; and OpenGL(R) Graphics with the X
  29 ** Window System(R) (Version 1.3), released October 19, 1998. This software
  30 ** was created using the OpenGL(R) version 1.2.1 Sample Implementation
  31 ** published by SGI, but has not been independently verified as being
  32 ** compliant with the OpenGL(R) version 1.2.1 Specification.
  33 **
  34 */
  35 /*
  36 */
  37
  38 #include <stdlib.h>
  39 #include <stdio.h>
  40
  41 #include "partitionX.h"
  42
  43 #define CONCAVITY_ZERO 1.0e-6 //this number is used to test whether a vertex is concave (refelx)
  44                               //or not. The test needs to compute the area of the three adjacent
  45                               //vertices to see if the are is positive or negative.
  46
  47 Int isCuspX(directedLine *v)
  48 {
  49   //if v->prev <= v && v->next <= v
  50   //|| v->prev >= v && v->next >= v
  51   Real* T = v->head();
  52   Real* P = v->getPrev()->head();
  53   Real* N = v->getNext()->head();
  54   if(
  55      (compV2InX(T,P) != -1 &&
  56       compV2InX(T,N) != -1
  57       ) ||
  58      (compV2InX(T,P) != 1 &&
  59       compV2InX(T,N) != 1
  60       )
  61      )
  62     return 1;
  63   else
  64     return 0;
  65 }
  66
  67 Int isReflexX(directedLine* v)
  68 {
  69   Real* A = v->getPrev()->head();
  70   Real* B = v->head();
  71   Real* C = v->tail();
  72   Real Bx,By, Cx, Cy;
  73   //scale them in case they are too small
  74   Bx = 10*(B[0] - A[0]);
  75   By = 10*(B[1] - A[1]);
  76   Cx = 10*(C[0] - A[0]);
  77   Cy = 10*(C[1] - A[1]);
  78
  79   if(Bx*Cy - Cx*By < -CONCAVITY_ZERO) return 1;
  80   else return 0;
  81 }
  82
  83
  84 /*return
  85  *0: not-cusp
  86  *1: interior cusp
  87  *2: exterior cusp
  88  */
  89 Int cuspTypeX(directedLine *v)
  90 {
  91   if(! isCuspX(v)) return 0;
  92   else
  93     {
  94 //printf("isCusp,%f,%f\n", v->head()[0], v->head()[1]);
  95       if(isReflexX(v))
  96         {
  97 //        printf("isReflex\n");
  98           return 1;
  99         }
 100       else
 101         {
 102 //        printf("not isReflex\n");
 103           return 2;
 104         }
 105     }
 106 }
 107
 108 Int numInteriorCuspsX(directedLine *polygon)
 109 {
 110   directedLine *temp;
 111   int ret = 0;
 112   if(cuspTypeX(polygon) == 1)
 113     ret++;
 114   for(temp = polygon->getNext(); temp != polygon; temp = temp->getNext())
 115     if(cuspTypeX(temp) == 1)
 116       ret++;
 117   return ret;
 118 }
 119
 120
 121 void findInteriorCuspsX(directedLine *polygon, Int& ret_n_interior_cusps,
 122                         directedLine** ret_interior_cusps)
 123 {
 124   directedLine *temp;
 125   ret_n_interior_cusps = 0;
 126   if(cuspTypeX(polygon) == 1)
 127     {
 128       ret_interior_cusps[ret_n_interior_cusps++] = polygon;
 129     }
 130   for(temp = polygon->getNext(); temp != polygon; temp = temp->getNext())
 131     if(cuspTypeX(temp) == 1)
 132       {
 133         ret_interior_cusps[ret_n_interior_cusps++] = temp;
 134       }
 135 }
 136
 137 directedLine* findDiagonal_singleCuspX(directedLine* cusp)
 138 {
 139   directedLine* temp;
 140   Int is_minimal = ((compV2InX(cusp->head(), cusp->tail()) == -1)? 1:0);
 141
 142   if(is_minimal)
 143     for(temp = cusp->getNext(); temp != cusp; temp = temp->getNext())
 144       {
 145         if(compV2InX(cusp->head(), temp->head()) == 1)
 146           {
 147             return temp;
 148           }
 149       }
 150   else //is maxmal
 151     for(temp = cusp->getNext(); temp != cusp; temp = temp->getNext())
 152       {
 153         if(compV2InX(cusp->head(), temp->head()) == -1)
 154           {
 155             return temp;
 156           }
 157       }
 158   return NULL;
 159 }
 160
 161
 162