overlay-pslg
Compute a regularized Boolean operation between the interiors of two planar straight line graphs.
Demo
- Click to add points
- Drag to create edges
- Toggle red/blue points by clicking upper left button
- Select different Boolean operations
Example
Here is a simple example showing how to use this module to compute the intersection of two PSLGs:
//Load the modulevar overlay = //Red PSLG - Define a trianglevar redPoints = 05 025 025 05 075 075var redEdges = 01 12 20 //Blue PSLG - Define a squarevar bluePoints = 025 025 025 06 06 06 06 025var blueEdges = 01 12 23 30 //Construct intersectionconsole
Output
The result of this module is the following JSON:
points: 06 06 044999999999999996 06 025 05 05 025 06 044999999999999996 red: 1 2 2 3 3 4 blue: 0 1 0 4
We can visualize this result as follows:
Install
To install this module, you can use npm. The command is as follows:
npm i overlay-pslg
It works in any reasonable CommonJS environment like node.js. If you want to use it in a browser, you should use browserify.
API
require('overlay-pslg')(redPoints, redEdges, bluePoints, blueEdges[, op])
Computes a Boolean operation between two planar straight line graphs.
redPoints, redEdges
are the points and edges of the first complexbluePoints, blueEdges
are the points and edges of the second complexop
the boolean operator to compute (Default"xor"
). Possible values include:"xor"
- computes the symmetric difference ofred
andblue
"and"
- computes the intersection ofred
andblue
"or"
- computes the union ofred
andblue
"sub"
- comutes the set difference,blue-red
"rsub"
- comutes the set difference,red-blue
Returns An object encoding a planar straight line graph with the edges partitioned into two sets:
points
are the points of the combined cell complexred
are the edges in the resulting pslg coming from the red graphblue
are the edges in the resulting pslg coming from the blue graph
Note The interiors of red and blue are computed using the same algorithm as cdt2d
, which is it counts the parity of the path with the fewest number of boundary crossings for each point. Even parity points are in the exterior, odd parity in the interior.
License
(c) 2015 Mikola Lysenko. MIT License