Function edgesIntersection

lib/offset-polygon.js:55–68

(edgeA, edgeB)

  return polygon;
}
function edgesIntersection(edgeA, edgeB) {
  const den = (edgeB.vertex2.y - edgeB.vertex1.y) * (edgeA.vertex2.x - edgeA.vertex1.x) - (edgeB.vertex2.x - edgeB.vertex1.x) * (edgeA.vertex2.y - edgeA.vertex1.y);
  if (den == 0) {
    return null;
  }
  const ua = ((edgeB.vertex2.x - edgeB.vertex1.x) * (edgeA.vertex1.y - edgeB.vertex1.y) - (edgeB.vertex2.y - edgeB.vertex1.y) * (edgeA.vertex1.x - edgeB.vertex1.x)) / den;
  const ub = ((edgeA.vertex2.x - edgeA.vertex1.x) * (edgeA.vertex1.y - edgeB.vertex1.y) - (edgeA.vertex2.y - edgeA.vertex1.y) * (edgeA.vertex1.x - edgeB.vertex1.x)) / den;
  const isIntersectionOutside = ua < 0 || ub < 0 || ua > 1 || ub > 1;
  return {
    x: edgeA.vertex1.x + ua * (edgeA.vertex2.x - edgeA.vertex1.x),
    y: edgeA.vertex1.y + ua * (edgeA.vertex2.y - edgeA.vertex1.y),
    isIntersectionOutside
  };
}
function appendArc(arcSegments, vertices, center, radius, startVertex, endVertex, isPaddingBoundary) {
  var startAngle = Math.atan2(startVertex.y - center.y, startVertex.x - center.x);
  var endAngle = Math.atan2(endVertex.y - center.y, endVertex.x - center.x);