simplicial-complex-contour

Finds a piecewise-linear isocontour on a simplicial complex using the marching simplex method.

Example

1var extractContour = require('simplicial-complex-contour')
2var bunny = require('bunny')
3
4//Solve for the curve z=0 on the surface of the bunny
5var zvalues = bunny.positions.map(function(p) {
6  return p[2]
7})
8var curve = extractContour(bunny.cells, zvalues, 0.0)
9
10//Unpack edges and positions of curve
11var curveEdges = curve.cells
12var curvePositions = curve.vertexWeights.map(function(w,i) {
13  var a = bunny.positions[curve.vertexIds[i][0]]
14  var b = bunny.positions[curve.vertexIds[i][1]]
15
16  return [
17    w * a[0] + (1 - w) * b[0],
18    w * a[1] + (1 - w) * b[1],
19    w * a[2] + (1 - w) * b[2]
20  ]
21})
22
23//Render the curve
24console.log({
25  cells: curveEdges,
26  positions: curvePositions
27})

Install

npm install simplicial-complex-contour

API

require('simplicial-complex-contour')(cells, values[, level])

Computes a piecewise linear solution to the solution values=levels

• cells is an array of simplices represented by tuples of vertex indices
• values is an array of values defined at each vertex of the cell complex
• level is the level at which the surface is extracted (Default 0)

Returns An object with 3 properties

• cells which are the cells of the extracted isosurface
• vertexIds which is an array of pairs of vertex ids encoding the crossing edges
• vertexWeights which are linear weights applied to each vertex

Credits

(c) 2014 Mikola Lysenko. MIT License