Question 1

How to use poly-decomp.js with a physics engine like Matter.js?

Accepted Answer

Preprocess concave shapes by decomposing them into convex polygons using quickDecomp for better performance, then pass each convex piece as a separate body or fixture in Matter.js. Ensure polygons are counter-clockwise with makeCCW first, and validate with isSimple to avoid issues.

Question 2

What's the real difference between quickDecomp and decomp in output quality?

Accepted Answer

quickDecomp is faster but may produce more convex pieces, while decomp is slower but minimizes the number of pieces for optimal decomposition. The README mentions this trade-off, so choose based on whether speed or precision is critical for your application.

Question 3

Can poly-decomp.js handle polygons with holes?

Accepted Answer

No, the library does not support holes in polygons natively; it assumes simple, non-self-intersecting polygons. You might need to preprocess hole-filled polygons by splitting them into separate contours before using isSimple and decomposition functions.

Question 4

How to visualize the decomposed polygons in a web browser?

Accepted Answer

Use the HTML5 Canvas API as shown in the Advanced usage example: iterate through the convexPolygons array, draw each polygon with moveTo and lineTo calls, and close the path. The demo link in the README provides a live example for reference.

Question 5

Is poly-decomp.js faster than other JavaScript geometry libraries like earcut?

Accepted Answer

poly-decomp.js focuses on convex decomposition, while earcut is for triangulation; they serve different purposes. For decomposition, poly-decomp.js is optimized with a fast algorithm, but performance varies based on polygon complexity—benchmark against alternatives if speed is crucial.

Question 6

What happens if isSimple returns false for my polygon?

Accepted Answer

The polygon self-intersects, making it unsafe to decompose directly. You need to fix the polygon by removing intersections or splitting it into simple parts before using makeCCW and decomposition functions, as the library does not handle this automatically.

Poly-Decomp.js

What is Poly-Decomp.js?

Overview

Use Cases

Best For

Related Projects

Found a gem we're missing?

Not Ideal For

Pros & Cons

Pros

Cons

Frequently Asked Questions