Function incidence

stackgl_modules/index.js:35910–35940

(from_cells, to_cells)

//Builds an index for an n-cell.  This is more general than dual, but less efficient
function incidence(from_cells, to_cells) {
  var index = new Array(from_cells.length)
  for(var i=0, il=index.length; i<il; ++i) {
    index[i] = []
  }
  var b = []
  for(var i=0, n=to_cells.length; i<n; ++i) {
    var c = to_cells[i]
    var cl = c.length
    for(var k=1, kn=(1<<cl); k<kn; ++k) {
      b.length = bits.popCount(k)
      var l = 0
      for(var j=0; j<cl; ++j) {
        if(k & (1<<j)) {
          b[l++] = c[j]
        }
      }
      var idx=findCell(from_cells, b)
      if(idx < 0) {
        continue
      }
      while(true) {
        index[idx++].push(i)
        if(idx >= from_cells.length || compareCells(from_cells[idx], b) !== 0) {
          break
        }
      }
    }
  }
  return index
}
__webpack_unused_export__ = incidence

//Computes the dual of the mesh.  This is basically an optimized version of buildIndex for the situation where from_cells is just the list of vertices