isob.c

一个开源的火灾动力模拟的系统

void FreeBlockInfo(bbyte *pbToFree){
  blockinfo *pbi, *pbiPrev;

  pbiPrev = NULL;
  for (pbi = pbiHead; pbi != NULL; pbi = pbi->pbiNext){
    if(fPtrEqual(pbi->pb, pbToFree)){
      if(pbiPrev == NULL){
        pbiHead = pbi->pbiNext;
      }
      else{
        pbiPrev->pbiNext = pbi->pbiNext;
      }
      break;
    }
    pbiPrev = pbi;
  }
  ASSERT(pbi != NULL);
  if(sizeofDebugByte!=0)ASSERT((char)*(pbi->pb+pbi->size)==(char)debugByte);
  free(pbi);
}

/* ------------------ UpdateBlockInfo ------------------------ */

void UpdateBlockInfo(bbyte *pbOld, bbyte *pbNew, size_t sizeNew){
  blockinfo *pbi;

  ASSERT(pbNew != NULL && sizeNew != 0);

  pbi = GetBlockInfo(pbOld);
  ASSERT(pbOld == pbi->pb);

  pbi->pb = pbNew;
  pbi->size = sizeNew;
}

/* ------------------ sizeofBlock ------------------------ */

size_t sizeofBlock(bbyte *pb){
  blockinfo *pbi;

  pbi = GetBlockInfo(pb);
  ASSERT(pb==pbi->pb);
  if(sizeofDebugByte!=0)ASSERT((char)*(pbi->pb+pbi->size)==(char)debugByte);
  return(pbi->size);
}

/* ------------------ ValidPointer ------------------------ */

mallocflag ValidPointer(void *pv, size_t size){
  blockinfo *pbi;
  bbyte *pb = (bbyte *)pv;

  ASSERT(pv != NULL && size != 0);

  pbi = GetBlockInfo(pb);
  ASSERT(pb==pbi->pb);

  ASSERT(fPtrLessEq(pb+size,pbi->pb + pbi->size));

  if(sizeofDebugByte!=0)ASSERT((char)*(pbi->pb+pbi->size)==(char)debugByte);
  return(1);
}

/* ------------------ strcpy ------------------------ */

char *_strcpy(char *s1, const char *s2){
  blockinfo *pbi;
  int offset;
  CheckMemory;
  pbi = GetBlockInfo_nofail(s1);
  if(pbi!=NULL){
    offset = s1 - pbi->pb;
    ASSERT(pbi->size - offset >= strlen(s2)+1);
  }

  return strcpy(s1,s2);
}

/* ------------------ strcat ------------------------ */

char *_strcat(char *s1, const char *s2){
  blockinfo *pbi;
  int offset;
  CheckMemory;
  pbi = GetBlockInfo_nofail(s1);
  if(pbi!=NULL){
    offset = s1 - pbi->pb;
    ASSERT(pbi->size - offset >= strlen(s1)+strlen(s2)+1);
  }

  return strcat(s1,s2);
}
#endif
/*lint -e534 */
/*lint -e553 */
/*lint -e537 */
/*lint -e732 loss of sign */
/*lint -e774 boolean within if always evaluates to True */
/*lint -e785 */
/*lint -e736 */
/*lint -e818 */
/*lint -e747 */
/*lint -e524 */
/*lint -e834 */
/*lint -e725 */
/*lint -e539 */
/*lint -e525 */
/*lint -e19 Expecting ; */
/*lint -e10 Useless declaration */

#include <stdlib.h>
#ifdef pp_DRAWISO
#include <GL/glut.h>
#endif
#include <math.h>
#include <stdio.h>
#define IN_ISOBOX

unsigned short *vertices=NULL;
int *rank=NULL,*sortedlist=NULL,*closestnodes=NULL;
int edge2vertex[12][2]={
  {0,1},{1,2},{2,3},{0,3},
  {0,4},{1,5},{2,6},{3,7},
  {4,5},{5,6},{6,7},{4,7}
};

int compcase[]={0,0,0,-1,0,0,-1,-1,0,0,0,0,-1,-1,0};

int edgelist[15][13]={
  { 0                             },
  { 3,0,4, 3                      },
  { 4,0,4, 7, 2                   },
  { 6,0,4, 3, 7,11,10             },
  { 6,0,4, 3, 6,10, 9             },
  { 5,0,3, 7, 6, 5                },
  { 7,0,4, 7, 2, 6,10,9           },
  { 9,4,8,11, 2, 3, 7,6,10,9      },
  { 4,4,7, 6, 5                   },
  { 6,2,6, 9, 8, 4, 3             },
  { 8,0,8,11, 3,10, 9,1, 2        },
  { 6,4,3, 2,10, 9, 5             },
  { 8,4,8,11, 0, 3, 7,6, 5        },
  {12,0,4, 3, 7,11,10,2, 6,1,8,5,9},
  { 6,3,7, 6, 9, 8, 0             }
};

int edgelist2[15][16]={
  { 0                             },
  { 0},
  { 0},
  { 8,3,0,10,7,0,4,11,10},
  { 0},
  { 0},
  { 11, 7,10,9,4,0,4,9,0,9,6,2},
  { 9,7,10,11,3,4,8,9,6,2},
  { 0},
  { 0},
  { 8,0,8,9,1,3,2,10,11},
  { 0},
  { 8,0,3,4,8,11,7,6,5},
  { 12,4,11,8,0,5,1,7,3,2,9,10,6},
  { 0}
};



int pathcclist[15][13]={
  { 0},
  { 3,0,1,2},
  { 6,0,1,2,2,3,0},
  { 6,0,1,2,3,4,5},
  { 6,0,1,2,3,4,5},
  { 9,0,1,2,2,3,4,0,2,4},
  { 9,0,1,2,2,3,0,4,5,6},
  { 9,0,1,2,3,4,5,6,7,8},
  { 6,0,1,2,2,3,0},
  {12,0,1,5,1,4,5,1,2,4,2,3,4},
  {12,0,1,2,0,2,3,4,5,6,4,6,7},
  {12,0,1,5,1,4,5,1,2,4,2,3,4},
  {12,0,1,2,3,4,5,3,5,6,3,6,7},
  {12,0,1,2,3,4,5,6,7,8,9,10,11},
  {12,0,1,5,1,4,5,1,2,4,2,3,4}
};

int pathcclist2[15][19]={
  { 0},
  { 0},
  { 0},
  { 12,0,1,2,0,2,3,4,5,6,4,6,7},
  { 0},
  { 0},
  { 15,0,1,2,0,2,3,4,5,6,7,8,9,7,9,10},
  { 15,0,1,2,3,4,5,3,5,7,3,7,8,5,6,7},
  { 0},
  { 0},
  { 12,0,1,2,0,2,3,4,5,6,4,6,7},
  { 0},
  { 12,0,1,2,3,4,6,3,6,7,4,5,6},
  { 12,0,1,2,3,4,5,6,7,8,9,10,11},
  { 0}
};



int pathccwlist[15][13]={
  { 0},
  { 3,0,2,1},
  { 6,0,2,1,0,3,2},
  { 6,0,2,1,3,5,4},
  { 6,0,2,1,3,5,4},
  { 9,0,2,1,2,4,3,0,4,2},
  { 9,0,2,1,0,3,2,4,6,5},
  { 9,0,2,1,3,5,4,6,8,7},
  { 6,0,2,1,0,3,2},
  {12,0,5,1,1,5,4,1,4,2,2,4,3},
  {12,0,2,1,0,3,2,4,6,5,4,7,6},
  {12,0,5,1,1,5,4,1,4,2,2,4,3},
  {12,0,2,1,3,5,4,3,6,5,3,7,6},
  {12,0,2,1,3,5,4,6,8,7,9,11,10},
  {12,0,5,1,1,5,4,1,4,2,2,4,3}
};

int pathccwlist2[15][19]={
  { 0},
  { 0},
  { 0},
  { 12,0,2,1,0,3,2,4,6,5,4,7,6},
  { 0},
  { 0},
  { 15,0,2,1,0,3,2,4,6,5,7,9,8,7,10,9},
  { 15,0,2,1,3,5,4,3,7,5,3,8,7,5,7,6},
  { 0},
  { 0},
  { 12,0,2,1,0,3,2,4,6,5,4,7,6},
  { 0},
  { 12,0,2,1,3,6,4,3,7,6,4,6,5},
  { 12,0,2,1,3,5,4,6,8,7,9,11,10},
  { 0}
};



int cases[256][10]={
{0,0,0,0,0,0,0,0, 0,  0},{0,1,2,3,4,5,6,7, 1,  1},{1,2,3,0,5,6,7,4, 1,  2},
{1,2,3,0,5,6,7,4, 2,  3},{2,3,0,1,6,7,4,5, 1,  4},{0,4,5,1,3,7,6,2, 3,  5},
{2,3,0,1,6,7,4,5, 2,  6},{3,0,1,2,7,4,5,6, 5,  7},{3,0,1,2,7,4,5,6, 1,  8},
{0,1,2,3,4,5,6,7, 2,  9},{3,7,4,0,2,6,5,1, 3, 10},{2,3,0,1,6,7,4,5, 5, 11},
{3,0,1,2,7,4,5,6, 2, 12},{1,2,3,0,5,6,7,4, 5, 13},{0,1,2,3,4,5,6,7, 5, 14},
{0,1,2,3,4,5,6,7, 8, 15},{4,0,3,7,5,1,2,6, 1, 16},{4,5,1,0,7,6,2,3, 2, 17},
{1,2,3,0,5,6,7,4, 3, 18},{5,1,0,4,6,2,3,7, 5, 19},{2,3,0,1,6,7,4,5, 4, 20},
{4,5,1,0,7,6,2,3, 6, 21},{2,3,0,1,6,7,4,5, 6, 22},{3,0,1,2,7,4,5,6,14, 23},
{4,5,1,0,7,6,2,3, 3, 24},{7,4,0,3,6,5,1,2, 5, 25},{2,6,7,3,1,5,4,0, 7, 26},
{3,0,1,2,7,4,5,6, 9, 27},{2,6,7,3,1,5,4,0, 6, 28},{4,0,3,7,5,1,2,6,11, 29},
{0,1,2,3,4,5,6,7,12, 30},{0,0,0,0,0,0,0,0, 0,  0},{5,4,7,6,1,0,3,2, 1, 32},
{0,3,7,4,1,2,6,5, 3, 33},{1,0,4,5,2,3,7,6, 2, 34},{4,5,1,0,7,6,2,3, 5, 35},
{2,3,0,1,6,7,4,5, 3, 36},{3,7,4,0,2,6,5,1, 7, 37},{6,2,1,5,7,3,0,4, 5, 38},
{0,1,2,3,4,5,6,7, 9, 39},{3,0,1,2,7,4,5,6, 4, 40},{3,7,4,0,2,6,5,1, 6, 41},
{5,6,2,1,4,7,3,0, 6, 42},{3,0,1,2,7,4,5,6,11, 43},{3,0,1,2,7,4,5,6, 6, 44},
{1,2,3,0,5,6,7,4,12, 45},{0,1,2,3,4,5,6,7,14, 46},{0,0,0,0,0,0,0,0, 0,  0},
{5,1,0,4,6,2,3,7, 2, 48},{1,0,4,5,2,3,7,6, 5, 49},{0,4,5,1,3,7,6,2, 5, 50},
{4,5,1,0,7,6,2,3, 8, 51},{4,7,6,5,0,3,2,1, 6, 52},{1,0,4,5,2,3,7,6,12, 53},
{4,5,1,0,7,6,2,3,11, 54},{0,0,0,0,0,0,0,0, 0,  0},{5,1,0,4,6,2,3,7, 6, 56},
{1,0,4,5,2,3,7,6,14, 57},{0,4,5,1,3,7,6,2,12, 58},{0,0,0,0,0,0,0,0, 0,  0},
{4,0,3,7,5,1,2,6,10, 60},{0,0,0,0,0,0,0,0, 0,  0},{0,0,0,0,0,0,0,0, 0,  0},
{0,0,0,0,0,0,0,0, 0,  0},{6,7,3,2,5,4,0,1, 1, 64},{0,1,2,3,4,5,6,7, 4, 65},
{1,0,4,5,2,3,7,6, 3, 66},{0,4,5,1,3,7,6,2, 6, 67},{2,1,5,6,3,0,4,7, 2, 68},
{6,7,3,2,5,4,0,1, 6, 69},{5,6,2,1,4,7,3,0, 5, 70},{0,1,2,3,4,5,6,7,11, 71},
{3,0,1,2,7,4,5,6, 3, 72},{0,1,2,3,4,5,6,7, 6, 73},{7,4,0,3,6,5,1,2, 7, 74},
{2,3,0,1,6,7,4,5,12, 75},{7,3,2,6,4,0,1,5, 5, 76},{1,2,3,0,5,6,7,4,14, 77},
{1,2,3,0,5,6,7,4, 9, 78},{0,0,0,0,0,0,0,0, 0,  0},{4,0,3,7,5,1,2,6, 3, 80},
{0,3,7,4,1,2,6,5, 6, 81},{2,3,0,1,6,7,4,5, 7, 82},{5,1,0,4,6,2,3,7,12, 83},
{2,1,5,6,3,0,4,7, 6, 84},{0,1,2,3,4,5,6,7,10, 85},{5,6,2,1,4,7,3,0,12, 86},
{0,0,0,0,0,0,0,0, 0,  0},{0,1,2,3,4,5,6,7, 7, 88},{7,4,0,3,6,5,1,2,12, 89},
{3,0,1,2,7,4,5,6,13, 90},{0,0,0,0,0,0,0,0, 0,  0},{7,3,2,6,4,0,1,5,12, 92},
{0,0,0,0,0,0,0,0, 0,  0},{0,0,0,0,0,0,0,0, 0,  0},{0,0,0,0,0,0,0,0, 0,  0},
{5,4,7,6,1,0,3,2, 2, 96},{6,2,1,5,7,3,0,4, 6, 97},{2,1,5,6,3,0,4,7, 5, 98},
{2,1,5,6,3,0,4,7,14, 99},{1,5,6,2,0,4,7,3, 5,100},{1,5,6,2,0,4,7,3,12,101},
{1,5,6,2,0,4,7,3, 8,102},{0,0,0,0,0,0,0,0, 0,  0},{5,4,7,6,1,0,3,2, 6,104},
{0,4,5,1,3,7,6,2,10,105},{2,1,5,6,3,0,4,7,12,106},{0,0,0,0,0,0,0,0, 0,  0},
{5,6,2,1,4,7,3,0,11,108},{0,0,0,0,0,0,0,0, 0,  0},{0,0,0,0,0,0,0,0, 0,  0},
{0,0,0,0,0,0,0,0, 0,  0},{7,6,5,4,3,2,1,0, 5,112},{0,4,5,1,3,7,6,2,11,113},
{6,5,4,7,2,1,0,3, 9,114},{0,0,0,0,0,0,0,0, 0,  0},{1,5,6,2,0,4,7,3,14,116},
{0,0,0,0,0,0,0,0, 0,  0},{0,0,0,0,0,0,0,0, 0,  0},{0,0,0,0,0,0,0,0, 0,  0},
{7,6,5,4,3,2,1,0,12,120},{0,0,0,0,0,0,0,0, 0,  0},{0,0,0,0,0,0,0,0, 0,  0},
{0,0,0,0,0,0,0,0, 0,  0},{0,0,0,0,0,0,0,0, 0,  0},{0,0,0,0,0,0,0,0, 0,  0},
{0,0,0,0,0,0,0,0, 0,  0},{0,0,0,0,0,0,0,0, 0,  0},{7,6,5,4,3,2,1,0, 1,128},
{0,1,2,3,4,5,6,7, 3,129},{1,2,3,0,5,6,7,4, 4,130},{1,2,3,0,5,6,7,4, 6,131},
{7,4,0,3,6,5,1,2, 3,132},{1,5,6,2,0,4,7,3, 7,133},{1,5,6,2,0,4,7,3, 6,134},
{3,0,1,2,7,4,5,6,12,135},{3,2,6,7,0,1,5,4, 2,136},{4,0,3,7,5,1,2,6, 5,137},
{7,4,0,3,6,5,1,2, 6,138},{2,3,0,1,6,7,4,5,14,139},{6,7,3,2,5,4,0,1, 5,140},
{2,3,0,1,6,7,4,5, 9,141},{1,2,3,0,5,6,7,4,11,142},{0,0,0,0,0,0,0,0, 0,  0},
{4,0,3,7,5,1,2,6, 2,144},{3,7,4,0,2,6,5,1, 5,145},{7,6,5,4,3,2,1,0, 6,146},
{1,0,4,5,2,3,7,6,11,147},{4,0,3,7,5,1,2,6, 6,148},{3,7,4,0,2,6,5,1,12,149},
{1,0,4,5,2,3,7,6,10,150},{0,0,0,0,0,0,0,0, 0,  0},{0,3,7,4,1,2,6,5, 5,152},
{4,0,3,7,5,1,2,6, 8,153},{0,3,7,4,1,2,6,5,12,154},{0,0,0,0,0,0,0,0, 0,  0},
{0,3,7,4,1,2,6,5,14,156},{0,0,0,0,0,0,0,0, 0,  0},{0,0,0,0,0,0,0,0, 0,  0},
{0,0,0,0,0,0,0,0, 0,  0},{5,1,0,4,6,2,3,7, 3,160},{1,2,3,0,5,6,7,4, 7,161},
{1,0,4,5,2,3,7,6, 6,162},{4,5,1,0,7,6,2,3,12,163},{3,0,1,2,7,4,5,6, 7,164},
{0,1,2,3,4,5,6,7,13,165},{6,2,1,5,7,3,0,4,12,166},{0,0,0,0,0,0,0,0, 0,  0},
{3,2,6,7,0,1,5,4, 6,168},{4,0,3,7,5,1,2,6,12,169},{1,2,3,0,5,6,7,4,10,170},
{0,0,0,0,0,0,0,0, 0,  0},{6,7,3,2,5,4,0,1,12,172},{0,0,0,0,0,0,0,0, 0,  0},
{0,0,0,0,0,0,0,0, 0,  0},{0,0,0,0,0,0,0,0, 0,  0},{6,5,4,7,2,1,0,3, 5,176},
{0,4,5,1,3,7,6,2, 9,177},{0,4,5,1,3,7,6,2,14,178},{0,0,0,0,0,0,0,0, 0,  0},
{6,5,4,7,2,1,0,3,12,180},{0,0,0,0,0,0,0,0, 0,  0},{0,0,0,0,0,0,0,0, 0,  0},
{0,0,0,0,0,0,0,0, 0,  0},{5,4,7,6,1,0,3,2,11,184},{0,0,0,0,0,0,0,0, 0,  0},
{0,0,0,0,0,0,0,0, 0,  0},{0,0,0,0,0,0,0,0, 0,  0},{0,0,0,0,0,0,0,0, 0,  0},
{0,0,0,0,0,0,0,0, 0,  0},{0,0,0,0,0,0,0,0, 0,  0},{0,0,0,0,0,0,0,0, 0,  0},
{7,3,2,6,4,0,1,5, 2,192},{6,5,4,7,2,1,0,3, 6,193},{7,3,2,6,4,0,1,5, 6,194},
{0,3,7,4,1,2,6,5,10,195},{3,2,6,7,0,1,5,4, 5,196},{3,2,6,7,0,1,5,4,12,197},
{3,2,6,7,0,1,5,4,14,198},{0,0,0,0,0,0,0,0, 0,  0},{2,6,7,3,1,5,4,0, 5,200},
{0,3,7,4,1,2,6,5,11,201},{2,6,7,3,1,5,4,0,12,202},{0,0,0,0,0,0,0,0, 0,  0},
{3,2,6,7,0,1,5,4, 8,204},{0,0,0,0,0,0,0,0, 0,  0},{0,0,0,0,0,0,0,0, 0,  0},
{0,0,0,0,0,0,0,0, 0,  0},{5,4,7,6,1,0,3,2, 5,208},{3,7,4,0,2,6,5,1,14,209},
{5,4,7,6,1,0,3,2,12,210},{0,0,0,0,0,0,0,0, 0,  0},{4,7,6,5,0,3,2,1,11,212},
{0,0,0,0,0,0,0,0, 0,  0},{0,0,0,0,0,0,0,0, 0,  0},{0,0,0,0,0,0,0,0, 0,  0},
{6,7,3,2,5,4,0,1, 9,216},{0,0,0,0,0,0,0,0, 0,  0},{0,0,0,0,0,0,0,0, 0,  0},
{0,0,0,0,0,0,0,0, 0,  0},{0,0,0,0,0,0,0,0, 0,  0},{0,0,0,0,0,0,0,0, 0,  0},
{0,0,0,0,0,0,0,0, 0,  0},{0,0,0,0,0,0,0,0, 0,  0},{4,7,6,5,0,3,2,1, 5,224},
{4,7,6,5,0,3,2,1,12,225},{1,5,6,2,0,4,7,3,11,226},{0,0,0,0,0,0,0,0, 0,  0},
{7,6,5,4,3,2,1,0, 9,228},{0,0,0,0,0,0,0,0, 0,  0},{0,0,0,0,0,0,0,0, 0,  0},
{0,0,0,0,0,0,0,0, 0,  0},{2,6,7,3,1,5,4,0,14,232},{0,0,0,0,0,0,0,0, 0,  0},
{0,0,0,0,0,0,0,0, 0,  0},{0,0,0,0,0,0,0,0, 0,  0},{0,0,0,0,0,0,0,0, 0,  0},
{0,0,0,0,0,0,0,0, 0,  0},{0,0,0,0,0,0,0,0, 0,  0},{0,0,0,0,0,0,0,0, 0,  0},
{5,4,7,6,1,0,3,2, 8,240},{0,0,0,0,0,0,0,0, 0,  0},{0,0,0,0,0,0,0,0, 0,  0},
{0,0,0,0,0,0,0,0, 0,  0},{0,0,0,0,0,0,0,0, 0,  0},{0,0,0,0,0,0,0,0, 0,  0},
{0,0,0,0,0,0,0,0, 0,  0},{0,0,0,0,0,0,0,0, 0,  0},{0,0,0,0,0,0,0,0, 0,  0},
{0,0,0,0,0,0,0,0, 0,  0},{0,0,0,0,0,0,0,0, 0,  0},{0,0,0,0,0,0,0,0, 0,  0},
{0,0,0,0,0,0,0,0, 0,  0},{0,0,0,0,0,0,0,0, 0,  0},{0,0,0,0,0,0,0,0, 0,  0},
{0,0,0,0,0,0,0,0, 0,  0}
};

/* ------------------ GetIsobox ------------------------ */

void GetIsobox(float *x, float *y, float *z, float *vals, float *tvals, int *nodeindexes, float level,
               float *xvert, float *yvert, float *zvert, float *tvert, int *closestnodes, int *nvert,
               int *triangles, int *ntriangles){
       /*
       INPUT
       -----
       x - x[0] = min x value
           x[1] = max x value
       y - y[0] = min y value
           y[1] = max y value
       z - z[0] = min z value
           z[1] = max z value

      vals - values at box formed by x,y,z
      tvals- values at box formed by x,y,z
      level - desired iso-surface level

       OUTPUT
       -----
       xvert, yvert, zvert - array of x,y,z coordinates that have iso-surface value 
       nvert - number of vertices
       triangles - set of 3 integer indices for each triangle pointing into xvert, yvert, zvert arrays
       ntriangles - number of indices in triangles

       */

  float vmin, vmax;
  float xxval[8],yyval[8],zzval[8];
  int bigger, casenum, type, sign;
  int ixmin[4]={0,1,4,5}, ixmax[4]={2,3,6,7};
  int iymin[4]={0,3,4,7}, iymax[4]={1,2,5,6};
  int izmin[4]={0,1,2,3}, izmax[4]={4,5,6,7};
  int n;
  int edge,*edges=NULL, nedges, *path=NULL, *case2=NULL, npath;
  int v1, v2;
  float val1, val2, denom, factor;
  float xx, yy, zz;
  int outofbounds;
  int prods[]={1,2,4,8,16,32,64,128};
  int thistype;

/* determine min and max solution values */
  vmin = vals[0]; vmax = vals[0];
  for(n=0;n<12;n++){closestnodes[n]=0;}
  for(n=1;n<8;n++){
    if(vals[n]<vmin){vmin=vals[n];}
    if(vals[n]>vmax){vmax=vals[n];}
  }

/* if the iso-surface level is not bounded by the vals data then there is nothing to do */

  *nvert = 0;
  *ntriangles = 0;
  if(vmin>level||vmax<level)return;

/* determine which of 256 cases this is */

  casenum = 0; bigger = 0;
  sign = 1;
  for(n=0;n<8;n++){
    if(vals[n]>level){
      bigger++; 
      casenum |= prods[n];
    }
  }

/* there are more nodes greater than the iso-surface level than below, so 
   solve the complementary problem */

  if(bigger>4){
    sign=-1; casenum=0;
    for(n=0;n<8;n++){
      if(vals[n]<level)casenum |= prods[n];
    }
  }

/* stuff min and max grid data into a more convenient form 
  assuming the following grid numbering scheme

       5-------6
     / |      /| 
   /   |     / | 
  4 -------7   |
  |    |   |   |  
  Z    1---|---2
  |  Y     |  /
  |/       |/
  0--X-----3     

  */

  for(n=0;n<4;n++){
    xxval[ixmin[n]] = x[0];
    xxval[ixmax[n]] = x[1];
    yyval[iymin[n]] = y[0];
    yyval[iymax[n]] = y[1];
    zzval[izmin[n]] = z[0];
    zzval[izmax[n]] = z[1];
  }

  if(casenum<=0||casenum>=255)return; /* no iso-surface */

  case2 = &(cases[casenum][0]);
  type = case2[8];
  if(type==0)return;

  if(compcase[type]==-1){thistype=sign;}
  else{thistype=1;}
 
  if(thistype!=-1){
    edges = &(edgelist[type][1]);
    if(sign>0)path = &(pathcclist[type][1]);   /* construct triangles clock wise */
     else{path = &(pathccwlist[type][1]);}     /* construct triangles counter clockwise */
  }
  else{
    edges = &(edgelist2[type][1]);
    if(sign>0)path = &(pathcclist2[type][1]);   /* construct triangles clock wise */
     else{path = &(pathccwlist2[type][1]);}     /* construct triangles counter clockwise */
  }
  npath = path[-1];
  nedges = edges[-1];

/* calculate where iso-surface level crosses each edge */

  outofbounds=0;
  for(n=0;n<nedges;n++){