/// <summary>
/// builds the Polygon edge normals. These are lazily created and updated only by the edgeNormals getter
/// </summary>
void BuildEdgeNormals()
{
// for boxes we only require 2 edges since the other 2 are parallel
var totalEdges = isBox ? 2 : Points.Length;
if (_edgeNormals == null || _edgeNormals.Length != totalEdges)
{
_edgeNormals = new Vector2[totalEdges];
}
Vector2 p2;
for (var i = 0; i < totalEdges; i++)
{
var p1 = Points[i];
if (i + 1 >= Points.Length)
{
p2 = Points[0];
}
else
{
p2 = Points[i + 1];
}
var perp = Vector2Ext.Perpendicular(ref p1, ref p2);
Vector2Ext.Normalize(ref perp);
_edgeNormals[i] = perp;
}
return;
}