1 files changed, 118 insertions, 0 deletions
diff --git a/Polygon.cpp b/Polygon.cpp
new file mode 100644
index 0000000..05d06ca
--- /dev/null
+++ b/Polygon.cpp
@@ -0,0 +1,118 @@
+#include "Polygon.h"
+#include <math.h>
+
+
+double Polygon::area() const {
+  double d = 0.0;
+  
+  for(const_iterator it = begin(); it != end(); it++) {
+    const_iterator it2 = it+1;
+    if(it2 == end()) it2 = begin();
+    
+    d += (it2->getX()+it->getX())*(it2->getY()-it->getY());
+  }
+  
+  return fabs(d/2);
+}
+
+double Polygon::perimeter() const {
+  double d = 0.0;
+  
+  for(const_iterator it = begin(); it != end(); it++) {
+    const_iterator it2 = it+1;
+    if(it2 == end()) it2 = begin();
+    
+    d += it->distance(*it2);
+  }
+  
+  return d;
+}
+
+int Polygon::quadrant(const Vertex &v) const {
+  if(v.getX() > 0 && v.getY() >= 0) return 1;
+  if(v.getX() >= 0 && v.getY() < 0) return 2;
+  if(v.getX() < 0 && v.getY() <= 0) return 3;
+  if(v.getX() <= 0 && v.getY() > 0) return 4;
+  
+  return 0;
+}
+
+bool Polygon::contains(const Vertex &v) const {
+  int d = 0;
+  int q, ql, q2;
+  LINE d1 = {Vertex(-1, -1), Vertex(1, 1)};
+  LINE d2 = {Vertex(-1, 1), Vertex(1, -1)};
+  LINE l;
+  Vertex v2;
+  
+  
+  if(empty()) return false;
+  
+  v2 = back() - v;
+  q = quadrant(v2);
+  
+  if(q == 0) return true;
+  
+  for(const_iterator it = begin(); it != end(); it++) {
+    ql = q;
+    
+    v2 = *it - v;
+    q = quadrant(v2);
+    
+    if(q == 0) return true;
+    
+    switch(q-ql) {
+      case 0:
+        break;
+      case 1:
+      case -3:
+        d++;
+        break;
+      case 3:
+      case -1:
+        d--;
+        break;
+      default:
+        l.v1 = ((it == begin()) ? back() : *(it-1)) - v;
+        l.v2 = v2;
+        
+        if(q == 1 || q == 3) {
+          if(!(lineIntersection(&l, &d2, &v2) & INTERSECTION_LINE)) return false;
+          
+          q2 = quadrant(v2);
+          if(q2 == 0) return true;
+          
+          if((q == 1 && q2 == 2) || (q == 3 && q2 == 4)) d -= 2;
+          else d += 2;
+        }
+        else {
+          if(!(lineIntersection(&l, &d1, &v2) & INTERSECTION_LINE)) return false;
+          
+          q2 = quadrant(v2);
+          if(q2 == 0) return true;
+          
+          if((q == 2 && q2 == 3) || (q == 4 && q2 == 1)) d -= 2;
+          else d += 2;
+        }
+    }
+  }
+  
+  return (d != 0);
+}
+
+bool Polygon::intersects(const LINE *l) const {
+  LINE line;
+  
+  for(Polygon::const_iterator it = begin(); it != end(); it++) {
+    Polygon::const_iterator it2 = it+1;
+    if(it2 == end()) it2 = begin();
+    
+    line.v1 = *it;
+    line.v2 = *it2;
+    
+    if(lineIntersection(l, &line, NULL) == INTERSECTION_SEGMENT_SEGMENT)
+      return true;
+  }
+  
+  return false;
+}