js-angusj-clipper
Polygon and line clipping and offsetting library for Javascript/Typescript
a port of Angus Johnson's clipper to WebAssembly/Asm.js
Install it with npm install --save js-angusj-clipper
To support this project star it on github!
What is this?
A library to make polygon clipping (boolean operations) and offsetting fast on Javascript thanks
to WebAssembly with a fallback to Asm.js, based on the excellent Polygon Clipping (also known as Clipper) library by
Angus Johnson.
Why?
Because sometimes performance does matter and I could not find a javascript library
as fast or as rock solid as the C++ version of Clipper.
As an example, the results of the benchmarks included on the test suite when running on my machine (node 9.10) are:
Note, pureJs is jsclipper, a pure JS port of the same library
500 boolean operations over two circles of 5000 points each
clipType: intersection, subjectFillType: evenOdd
√ wasm (432 ms)
√ asmJs (1002 ms)
√ pureJs (1183 ms)
clipType: union, subjectFillType: evenOdd
√ wasm (507 ms)
√ asmJs (1058 ms)
√ pureJs (1037 ms)
clipType: difference, subjectFillType: evenOdd
√ wasm (437 ms)
√ asmJs (917 ms)
√ pureJs (948 ms)
clipType: xor, subjectFillType: evenOdd
√ wasm (504 ms)
√ asmJs (1053 ms)
√ pureJs (1958 ms)
10000 boolean operations over two circles of 100 points each
clipType: intersection, subjectFillType: evenOdd
√ wasm (281 ms)
√ asmJs (562 ms)
√ pureJs (333 ms)
clipType: union, subjectFillType: evenOdd
√ wasm (332 ms)
√ asmJs (653 ms)
√ pureJs (362 ms)
clipType: difference, subjectFillType: evenOdd
√ wasm (299 ms)
√ asmJs (570 ms)
√ pureJs (326 ms)
clipType: xor, subjectFillType: evenOdd
√ wasm (346 ms)
√ asmJs (644 ms)
√ pureJs (368 ms)
100 offset operations over a circle of 5000 points
joinType: miter, endType: closedPolygon, delta: 5
√ wasm (201 ms)
√ asmJs (612 ms)
√ pureJs (1156 ms)
joinType: miter, endType: closedPolygon, delta: 0
√ wasm (59 ms)
√ asmJs (181 ms)
√ pureJs (184 ms)
joinType: miter, endType: closedPolygon, delta: -5
√ wasm (231 ms)
√ asmJs (565 ms)
√ pureJs (1209 ms)
5000 offset operations over a circle of 100 points
joinType: miter, endType: closedPolygon, delta: 5
√ wasm (149 ms)
√ asmJs (280 ms)
√ pureJs (413 ms)
joinType: miter, endType: closedPolygon, delta: 0
√ wasm (123 ms)
√ asmJs (232 ms)
√ pureJs (248 ms)
joinType: miter, endType: closedPolygon, delta: -5
√ wasm (235 ms)
√ asmJs (499 ms)
√ pureJs (1012 ms)
More or less, the results for boolean operations over moderately big polygons are:
- Pure JS port of the Clipper library: ~1.0s, baseline
- This library (WebAssembly): ~0.5s
- This library (Asm.js): ~1.0s (mostly due to the emulation of 64-bit integer operations)
and for small polygons are:
- Pure JS port of the Clipper library: ~1.0s, baseline
- This library (WebAssembly): ~1.0s (due to the overhead of copying structures to/from JS/C++)
- This library (Asm.js): ~2.0s (mostly due to the emulation of 64-bit integer operations + the overhead of copying structures to/from JS/C++)
As for offsetting, the results for a moderately big polygon are:
- Pure JS port of the Clipper library: ~1s, baseline
- This library (WebAssembly): ~0.15s
- This library (Asm.js): ~0.56s
and for small polygons are:
- Pure JS port of the Clipper library: ~1s, baseline
- This library (WebAssembly): ~0.28s
- This library (Asm.js): ~0.65s
Getting started
// universal version
// import it with
import * as clipperLib from "js-angusj-clipper"; // es6 / typescript
// or
const clipperLib = require("js-angusj-clipper"); // nodejs style require
// web-only version (for example for angular 6+)
// import it with
import * as clipperLib from "js-angusj-clipper/web"; // es6 / typescript
// or
const clipperLib = require("js-angusj-clipper/web"); // nodejs style require
async function mainAsync() {
// create an instance of the library (usually only do this once in your app)
const clipper = await clipperLib.loadNativeClipperLibInstanceAsync(
// let it autodetect which one to use, but also available WasmOnly and AsmJsOnly
clipperLib.NativeClipperLibRequestedFormat.WasmWithAsmJsFallback
);
// create some polygons (note that they MUST be integer coordinates)
const poly1 = [{ x: 0, y: 0 }, { x: 10, y: 0 }, { x: 10, y: 10 }, { x: 0, y: 10 }];
const poly2 = [{ x: 10, y: 0 }, { x: 20, y: 0 }, { x: 20, y: 10 }, { x: 10, y: 10 }];
// get their union
const polyResult = clipper.clipToPaths({
clipType: clipperLib.ClipType.Union,
subjectInputs: [{ data: poly1, closed: true }],
clipInputs: [{ data: poly2 }],
subjectFillType: clipperLib.PolyFillType.EvenOdd
});
/* polyResult will be:
[
[
{ x: 0, y: 0 },
{ x: 20, y: 0 },
{ x: 20, y: 10 },
{ x: 0, y: 10 }
]
]
*/
}
mainAsync();
For an in-depth description of the library see: