From acfb3a4500c7eb2a093c4df5241faceb5c65e276 Mon Sep 17 00:00:00 2001
From: karl <karl.bittner@hexaquo.at>
Date: Sat, 28 Nov 2020 21:11:32 +0100
Subject: [PATCH] More Quickhull implementation; add Triangle class

---
 Line.h      |  2 +-
 Makefile    |  4 ++--
 Quickhull.h | 27 +++++++++++++++++++++++++++
 Triangle.h  | 22 ++++++++++++++++++++++
 4 files changed, 52 insertions(+), 3 deletions(-)
 create mode 100644 Triangle.h

diff --git a/Line.h b/Line.h
index 1727495..b156d02 100644
--- a/Line.h
+++ b/Line.h
@@ -22,7 +22,7 @@ public:
 
     // Return true if the given point is to the right of this line.
     // False is also returned if the point is directly on the line.
-    bool is_point_right(Point other)
+    bool is_point_right(Point other) const
     {
         other -= from();
 
diff --git a/Makefile b/Makefile
index a1ab1a7..109ae4d 100644
--- a/Makefile
+++ b/Makefile
@@ -7,9 +7,9 @@ CXXFLAGS = -Wall -O3
 # If SFML is not installed in a standard path, you need to tell the dynamic linker where to find the SFML libraries first by specifying LD_LIBRARY_PATH:
 # export LD_LIBRARY_PATH=<sfml-install-path>/lib && ./sfml-app
 
-quickhull: main.o Quickhull.h Point.h Line.h Timing.o Display.o
+quickhull: main.o Quickhull.h Point.h Line.h Triangle.h Timing.o Display.o
 	# link with sfml libs; -lsfml-network -lsfml-audio currently not needed
-	$(CXX) $(CXXFLAGS) -o quickhull main.o Quickhull.h Point.h Line.h Timing.o Display.o -lsfml-system -lsfml-window -lsfml-graphics
+	$(CXX) $(CXXFLAGS) -o quickhull main.o Quickhull.h Point.h Line.h Triangle.h Timing.o Display.o -lsfml-system -lsfml-window -lsfml-graphics
 
 main.o: main.cpp Timing.h
 	$(CXX) $(CXXFLAGS) -c main.cpp
diff --git a/Quickhull.h b/Quickhull.h
index c458cb2..a49ade5 100644
--- a/Quickhull.h
+++ b/Quickhull.h
@@ -5,6 +5,7 @@
 
 #include "Point.h"
 #include "Line.h"
+#include "Triangle.h"
 
 class Quickhull
 {
@@ -61,10 +62,36 @@ private:
         if (input.empty()) return;
 
         // Find the point which is furthest away from the line, add it to the output
+        Point furthest_point;  // TODO
+
+        output.emplace_back(furthest_point);
 
         // Build a triangle with these 3 points
+
+        // The order with which we must pass the points depends on where the new furthest point is
+        Point a, b, c;
+        if (line.is_point_right(furthest_point))
+        {
+            a = line.from();
+            b = line.to();
+            c = furthest_point;
+        }
+        else
+        {
+            a = line.from();
+            b = furthest_point;
+            c = line.to();
+        }
+        
+        Triangle triangle(a, b, c);
+
         // Remove points inside this triangle
+        input.remove_if([triangle](Point point)
+        {
+            return !triangle.is_point_inside(point);
+        });
 
         // Recursively call get_hull_with_line for each side of the triangle
+        // TODO
     }
 };
\ No newline at end of file
diff --git a/Triangle.h b/Triangle.h
new file mode 100644
index 0000000..d271c1a
--- /dev/null
+++ b/Triangle.h
@@ -0,0 +1,22 @@
+#pragma once
+
+#include "Point.h"
+#include "Line.h"
+
+class Triangle
+{
+private:
+    Point m_p1, m_p2, m_p3;
+    Line m_l1, m_l2, m_l3;
+
+public:
+    // The points must come in __clockwise__ order.
+    Triangle(Point p1, Point p2, Point p3)
+            : m_p1(p1), m_p2(p2), m_p3(p3),
+              m_l1(Line(p1, p2)), m_l2(Line(p2, p3)), m_l3(Line(p3, p1)) {}
+
+    bool is_point_inside(Point other) const
+    {
+        return m_l1.is_point_right(other) && m_l2.is_point_right(other) && m_l3.is_point_right(other);
+    }
+};
\ No newline at end of file