From 841c876a66cd9829d61ec07cd7a5041105516e0d Mon Sep 17 00:00:00 2001
From: Jack Andersen <jackoalan@gmail.com>
Date: Sat, 19 Jan 2019 20:41:51 -1000
Subject: [PATCH] Add CAABox::projectedPointTest

---
 include/zeus/CAABox.hpp |  2 ++
 src/CAABox.cpp          | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 34 insertions(+)

diff --git a/include/zeus/CAABox.hpp b/include/zeus/CAABox.hpp
index 4c8b23e..2f36713 100644
--- a/include/zeus/CAABox.hpp
+++ b/include/zeus/CAABox.hpp
@@ -302,6 +302,8 @@ public:
     return ret;
   }
 
+  bool projectedPointTest(const CMatrix4f& mvp, const CVector2f& point) const;
+
   void splitX(CAABox& negX, CAABox& posX) const {
     float midX = (max.x() - min.x()) * .5f + min.x();
     posX.max = max;
diff --git a/src/CAABox.cpp b/src/CAABox.cpp
index 4fb9558..217269d 100644
--- a/src/CAABox.cpp
+++ b/src/CAABox.cpp
@@ -4,4 +4,36 @@
 namespace zeus {
 const CAABox CAABox::skInvertedBox = CAABox();
 const CAABox CAABox::skNullBox = CAABox(CVector3f::skZero, CVector3f::skZero);
+
+static const int ProjWindings[6][4] = {
+  {2, 0, 4, 6}, // -X
+  {0, 1, 5, 4}, // -Y
+  {2, 3, 1, 0}, // -Z
+  {1, 3, 7, 5}, // +X
+  {3, 2, 6, 7}, // +Y
+  {4, 5, 7, 6}, // +Z
+};
+
+static bool testProjectedLine(const CVector2f& a, const CVector2f& b, const CVector2f& point) {
+  zeus::CVector2f normal = (b - a).perpendicularVector().normalized();
+  return point.dot(normal) >= a.dot(normal);
+}
+
+bool CAABox::projectedPointTest(const CMatrix4f& mvp, const CVector2f& point) const {
+  CVector2f projPoints[8];
+  for (int i = 0; i < 8; ++i)
+    projPoints[i] = mvp.multiplyOneOverW(getPoint(i)).toVec2f();
+
+  for (int i = 0, j; i < 6; ++i) {
+    for (j = 0; j < 3; ++j) {
+      if (!testProjectedLine(projPoints[ProjWindings[i][j]], projPoints[ProjWindings[i][j + 1]], point))
+        break;
+    }
+    if (j == 3 && testProjectedLine(projPoints[ProjWindings[i][3]], projPoints[ProjWindings[i][0]], point))
+      return true;
+  }
+
+  return false;
+}
+
 } // namespace zeus