CGE2: Implement CGE2Engine::mapCross().

Rework Map during the process.

engines/cge2/hero.cpp

@@ -28,6 +28,7 @@
 #include "cge2/hero.h"
 #include "cge2/text.h"
 #include "cge2/cge2_main.h"
+#include "cge2/map.h"
 
 namespace CGE2 {
 
@@ -437,8 +438,23 @@ int Hero::mapCross(const V3D &a, const V3D &b) {
 }
 
 int CGE2Engine::mapCross(const V2D &a, const V2D &b) {
-	warning("STUB: CGE2Engine::mapCross()");
-	return 0;
+	int cnt = 0;
+	V2D *n0 = nullptr;
+	V2D *p = nullptr;
+	for (int i = 0; i < _map->size(); i++) {
+		V2D *n = _map->getCoord(i);
+		if (p) {
+			if (cross(a, b, *n0, *n))
+				++cnt;
+		
+			if (n == p)
+				p = nullptr;	
+		} else {
+			p = n;
+		}
+		n0 = n;
+	}
+	return cnt;
 }
 
 void Hero::setCave(int c) {

engines/cge2/map.cpp

@@ -86,8 +86,8 @@ int Map::size() {
 	return _container.size();
 }
 
-V2D &Map::operator[](int idx) {
-	return _container[idx];
+V2D *Map::getCoord(int idx) {
+	return &_container[idx];
 }
 
 } // End of namespace CGE2

engines/cge2/map.h

@@ -47,7 +47,7 @@ public:
 	void clear();
 	void load(int scene);
 	int size();
-	V2D &operator[](int idx);
+	V2D *getCoord(int idx);
 };
 
 } // End of namespace CGE2