From 96b08ee75c80528c9858b052d3ee0751e138d76e Mon Sep 17 00:00:00 2001
From: Jan Niklas Hasse <jhasse@bixense.com>
Date: Thu, 21 Feb 2019 14:34:37 +0100
Subject: [PATCH] Add new function Triangle::CircumcicleContains

---
 meson.build               |  1 +
 poly2tri/common/shapes.cc | 24 ++++++++++++++++++++++++
 poly2tri/common/shapes.h  |  4 ++++
 unittest/TriangleTest.cpp | 15 +++++++++++++++
 4 files changed, 44 insertions(+)
 create mode 100644 unittest/TriangleTest.cpp

diff --git a/meson.build b/meson.build
index 7c0dfcb..44c118d 100644
--- a/meson.build
+++ b/meson.build
@@ -14,6 +14,7 @@ boost_test_dep = dependency('boost', modules : [ 'unit_test_framework' ], requir
 if boost_test_dep.found()
 	test('Unit Test', executable('unittest', [
 		'unittest/main.cpp',
+		'unittest/TriangleTest.cpp',
 	], dependencies : [boost_test_dep, thread_dep], link_with : lib))
 endif
 
diff --git a/poly2tri/common/shapes.cc b/poly2tri/common/shapes.cc
index fe99a8d..e7130a5 100644
--- a/poly2tri/common/shapes.cc
+++ b/poly2tri/common/shapes.cc
@@ -365,4 +365,28 @@ void Triangle::DebugPrint()
   std::cout << *points_[0] << " " << *points_[1] << " " << *points_[2] << std::endl;
 }
 
+bool Triangle::CircumcicleContains(const Point& point) const
+{
+  assert(IsCounterClockwise());
+  const double dx = points_[0]->x - point.x;
+  const double dy = points_[0]->y - point.y;
+  const double ex = points_[1]->x - point.x;
+  const double ey = points_[1]->y - point.y;
+  const double fx = points_[2]->x - point.x;
+  const double fy = points_[2]->y - point.y;
+
+  const double ap = dx * dx + dy * dy;
+  const double bp = ex * ex + ey * ey;
+  const double cp = fx * fx + fy * fy;
+
+  return (dx * (fy * bp - cp * ey) - dy * (fx * bp - cp * ex) + ap * (fx * ey - fy * ex)) < 0;
+}
+
+bool Triangle::IsCounterClockwise() const
+{
+  return (points_[1]->x - points_[0]->x) * (points_[2]->y - points_[0]->y) -
+             (points_[2]->x - points_[0]->x) * (points_[1]->y - points_[0]->y) >
+         0;
+}
+
 }
diff --git a/poly2tri/common/shapes.h b/poly2tri/common/shapes.h
index 7f0b1e7..272aefd 100644
--- a/poly2tri/common/shapes.h
+++ b/poly2tri/common/shapes.h
@@ -207,8 +207,12 @@ Triangle& NeighborAcross(const Point& opoint);
 
 void DebugPrint();
 
+bool CircumcicleContains(const Point&) const;
+
 private:
 
+bool IsCounterClockwise() const;
+
 /// Triangle points
 Point* points_[3];
 /// Neighbor list
diff --git a/unittest/TriangleTest.cpp b/unittest/TriangleTest.cpp
new file mode 100644
index 0000000..bdeeae7
--- /dev/null
+++ b/unittest/TriangleTest.cpp
@@ -0,0 +1,15 @@
+#include <boost/test/unit_test.hpp>
+#include <poly2tri/common/shapes.h>
+
+BOOST_AUTO_TEST_CASE(TriangleTest)
+{
+  p2t::Point a(0, 0);
+  p2t::Point b(1, 0);
+  p2t::Point c(0.5, .5);
+  p2t::Triangle triangle(a, b, c);
+  BOOST_CHECK(triangle.Contains(&a));
+  BOOST_CHECK(triangle.Contains(&b));
+  BOOST_CHECK(triangle.Contains(&c));
+  BOOST_CHECK(triangle.CircumcicleContains(p2t::Point(0.5, 0.1)));
+  BOOST_CHECK(!triangle.CircumcicleContains(p2t::Point(1, 0.4)));
+}