_drawEdges(ctx) {
    const edges = this.body.edges;
    const edgeIndices = this.body.edgeIndices;

    for (let i = 0; i < edgeIndices.length; i++) {
      const edge = edges[edgeIndices[i]];
      if (edge.connected === true) {
        edge.draw(ctx);
      }
    }
  }
Redraw all edges
@param {CanvasRenderingContext2D} ctx  2D context of a HTML canvas
@private