code: function buildEdgeVertex(index, x, y, tileBody, isGhost) {
  	let vertex = {
  		x: x,
  		y: y,
  		index: index,
  		body: tileBody,
  		isInternal: false,
  		isGhost: isGhost,
  		contact: null
  	};
  	
  	vertex.contact = {
  		vertex: vertex,
  		normalImpulse: 0,
  		tangentImpulse: 0
  	};
  	
  	return vertex;
  }
docs: Build a vertex for an edge.
  
  @param {int} index
  @param {number} x
  @param {number} y
  @param {Object} tileBody
  @param {boolean} [isGhost]