Function createPaddingPolygon

src/offset-polygon.ts:241–287

(
  polygon: Polygon,
  offset: number,
  arcSegments: number
)

}

function createPaddingPolygon(
  polygon: Polygon,
  offset: number,
  arcSegments: number
): Polygon {
  const offsetEdges: OffsetEdge[] = [];

  for (let i = 0; i < polygon.edges.length; i++) {
    const edge = polygon.edges[i];
    const dx = edge.inwardNormal.x * offset;
    const dy = edge.inwardNormal.y * offset;
    offsetEdges.push(createOffsetEdge(edge, dx, dy));
  }

  const vertices: Vector[] = [];

  for (let i = 0; i < offsetEdges.length; i++) {
    const thisEdge = offsetEdges[i];
    const prevEdge =
      offsetEdges[(i + offsetEdges.length - 1) % offsetEdges.length];
    const vertex = edgesIntersection(prevEdge, thisEdge);
    if (vertex && (!vertex.isIntersectionOutside || arcSegments < 1)) {
      vertices.push({
        x: vertex.x,
        y: vertex.y,
      });
    } else {
      const arcCenter = polygon.edges[i].vertex1;

      appendArc(
        arcSegments,
        vertices,
        arcCenter,
        offset,
        prevEdge.vertex2,
        thisEdge.vertex1,
        true
      );
    }
  }

  const paddingPolygon = createPolygon(vertices);

  paddingPolygon.offsetEdges = offsetEdges;

  return paddingPolygon;
}

export default function offsetPolygon(
  vertices: Vector[],