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https://github.com/mikolalysenko/surface-nets
Arbitrary dimensional level sets
https://github.com/mikolalysenko/surface-nets
Last synced: 20 days ago
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Arbitrary dimensional level sets
- Host: GitHub
- URL: https://github.com/mikolalysenko/surface-nets
- Owner: mikolalysenko
- License: mit
- Created: 2014-04-08T23:18:50.000Z (over 10 years ago)
- Default Branch: master
- Last Pushed: 2021-09-13T19:29:20.000Z (about 3 years ago)
- Last Synced: 2024-11-18T19:51:11.340Z (25 days ago)
- Language: JavaScript
- Size: 905 KB
- Stars: 101
- Watchers: 8
- Forks: 12
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
- awesome-regl - surface-nets
README
surface-nets
============
Extract a simplicial level set from an [ndarray](https://github.com/mikolalysenko/ndarray) in any dimension using naive surface nets. This module works in both node.js and with [browserify](http://browserify.org/)!
If you are doing experiments with greedy meshing or working with rectangular data, then you might want [contour2d](https://github.com/mikolalysenko/contour2d) instead.
# Example
Here is a 2D example:
```javascript
//Load modules
var surfaceNets = require("surface-nets")
var ndarray = require("ndarray")
var fill = require("ndarray-fill")
//Initialize array to a circle
var array = ndarray(new Float32Array(32*32), [32,32])
fill(array, function(i,j) {
return Math.pow(i-16,2) + Math.pow(j-16,2)
})
//Extract 2D contour (this is all there is to it!)
var complex = surfaceNets(array, 15*15)
//Write SVG image to stdout
var svgFile = ['']
complex.cells.forEach(function(cell) {
var p0 = complex.positions[cell[0]]
var p1 = complex.positions[cell[1]]
svgFile.push('')
})
complex.positions.forEach(function(p) {
svgFile.push('')
})
svgFile.push('')
console.log(svgFile.join(""))
```
And here is the output SVG:
This module also works in 3D. Here is an example:
```javascript
//Load modules
var surfaceNets = require("surface-nets")
var ndarray = require("ndarray")
var fill = require("ndarray-fill")
var mat4 = require("gl-matrix").mat4
//Initialize array
var array = ndarray(new Float32Array(32*32*32), [32,32,32])
fill(array, function(i,j,k) {
return Math.pow(i-16,2) + Math.pow(j-16,2) + Math.pow(k-16,2)
})
//Generate surface! (again, just one line)
var complex = surfaceNets(array, 100)
//Render the implicit surface to stdout
console.log('')
console.log(require("svg-3d-simplicial-complex")(
complex.cells,
complex.positions, {
view: mat4.lookAt(
mat4.create(),
[32, 32, 32],
[16, 16, 16],
[0,1,0]),
projection: mat4.perspective(mat4.create(),
Math.PI/4.0,
1.0,
0.1,
1000.0),
viewport: [[0,0], [512,512]]
}))
console.log("")
```
And here is the result:
And while it is a bit trivial, you can also generate surfaces in 1D:
```javascript
var surfaceNets = require("surface-nets")
var ndarray = require("ndarray")
console.log(surfaceNets(ndarray([1, -1, 0, 5, -10])))
```
Output:
```javascript
{ positions: [ [ 0.5 ], [ 2 ], [ 3.3333333333333335 ] ],
cells: [ [ 0 ], [ 1 ], [ 2 ] ] }
```
The code *should* work in 4D and higher dimensions, but this is not well tested and it is harder to visualize. (Also, why would you want to bother!?!)
# Install
```
npm install surface-nets
```
# API
#### `require("surface-nets")(array[,level])`
Extracts the level set at `level` from `array` as a simplicial complex.
* `array` is an [ndarray](https://github.com/mikolalysenko/ndarray)
* `level` is an optional number which determines the level at which the levelset is evaluated (default `0`)
**Returns** An object with a pair of properties representing a simplicial complex:
* `positions` is an array encoding the positions of the vertices. The coordinates of the positions are with respect to the indices in `array`.
* `cells` is an array encoding the cells of the simplicial complex as tuples of indices into the `position` array.
# Credits
(c) 2014 Mikola Lysenko. MIT License