use corners, store vectors

rename extensions, update playground

Pod/Classes/Perspective.swift

@@ -9,19 +9,19 @@
 import simd
 
 public final class Perspective {
-    let quadrilateral : Quadrilateral
+    let vectors : [Vector3Type]
 
     public init(_ q: Quadrilateral) {
-        quadrilateral = q
+        vectors = q.corners.map{$0.homogeneous3dvector}
     }
 
     lazy var basisVectorsToPointsMap: Matrix3x3Type! = {
         let m = Matrix3x3Type([
-            self.quadrilateral.p1.homogeneous3dvector,
-            self.quadrilateral.p2.homogeneous3dvector,
-            self.quadrilateral.p3.homogeneous3dvector]
+            self.vectors[0],
+            self.vectors[1],
+            self.vectors[2]]
         )
-        let solution = m.homogeneousInverse() * self.quadrilateral.p4.homogeneous3dvector
+        let solution = m.homogeneousInverse() * self.vectors[3]
         let scale = Matrix3x3Type(diagonal: solution)
         let basisToPoints = m * scale
         return basisToPoints.zNormalized()

Pod/Classes/Quardilateral.swift

@@ -9,16 +9,10 @@
 import UIKit
 
 public final class Quadrilateral {
-    public let p1 : CGPoint
-    public let p2 : CGPoint
-    public let p3 : CGPoint
-    public let p4 : CGPoint
+    public let corners : [CGPoint]
 
     public init(_ points:[CGPoint]) {
-        p1 = points[0]
-        p2 = points[1]
-        p3 = points[2]
-        p4 = points[3]
+        corners = points
     }
     public convenience init(_ origin:CGPoint, _ size:CGSize) {
         self.init([