1 files changed, 20 insertions, 1 deletions

diff --git a/geometry.c b/geometry.c
index 057fea0..248f354 100644
--- a/geometry.c
+++ b/geometry.c
@@ -44,7 +44,6 @@ double vertexDistance(const VERTEX *v1, const VERTEX *v2) {
   return sqrt(vertexDistanceSquare(v1, v2));
 }
 
-
 int vertexInRect(const VERTEX *v, const RECTANGLE *rect) {
   int ret = EDGE_NONE;
   
@@ -133,6 +132,26 @@ gboolean vertexInPolygon(const VERTEX *v, const POLYGON *p) {
   return (d == 0) ? FALSE : TRUE;
 }
 
+double polygonPerimeter(const POLYGON *p) {
+  int i;
+  double d = 0.0;
+  
+  for(i = 0; i < p->nVertices; i++)
+    d += vertexDistance(&p->vertices[i], &p->vertices[(i+1)%p->nVertices]);
+  
+  return d;
+}
+
+double polygonArea(const POLYGON *p) {
+  int i;
+  double d = 0.0;
+  
+  for(i = 0; i < p->nVertices; i++)
+    d += (p->vertices[(i+1)%p->nVertices].x+p->vertices[i].x)*(p->vertices[(i+1)%p->nVertices].y-p->vertices[i].y);
+  
+  return d/2;
+}
+
 int lineIntersection(const LINE *la, const LINE *lb, VERTEX *v) {
   double xa1 = la->v1.x, ya1 = la->v1.y;
   double xa2 = la->v2.x, ya2 = la->v2.y;