Code for some of the basic game design - selecting existing nodes, limiting edge distance

gamecore.cpp

@@ -5,11 +5,15 @@
 #include <iostream>
 #endif
 
+int GameCore::NODE_SIZE = 25;
+int GameCore::MAX_MOVE_DISTANCE = 200;
+
 GameCore::GameCore()
 {
     display = NULL;
     background = NULL;
     node = NULL;
+    move_template = NULL;
     is_running = true;
 }
 
@@ -51,7 +55,11 @@ bool GameCore::init()
     node = DrawUtils::load("node.bmp");
     DrawUtils::transpare(node, 255, 0, 255);
 
-    if (background == NULL || node == NULL)
+    move_template = DrawUtils::load("move_template.bmp");
+    DrawUtils::transpare(move_template, 255, 0, 255);
+    SDL_SetAlpha(move_template, SDL_SRCALPHA, 128);
+
+    if (background == NULL || node == NULL || move_template == NULL)
     {
 #ifdef DEBUG
 	std::cerr << "GameCore::init(): error: Couldn't load an image file\n";
@@ -85,6 +93,13 @@ void GameCore::render()
 			     0x000000);
     }
 
+    if (graph.get_current_vertex() != NULL)
+    {
+	Vertex* v = graph.get_current_vertex();
+	DrawUtils::draw(display, move_template, v->x, v->y);
+    }
+
+
     SDL_Flip(display);
 }
 
@@ -112,5 +127,13 @@ void GameCore::on_exit()
 
 void GameCore::on_lbutton_down(int x, int y)
 {
-    graph.add_vertex(x, y, 25);
+    Vertex* v = graph.get_current_vertex();
+    Vertex new_v = Vertex();
+    new_v.x = x;
+    new_v.y = y;
+
+    if (v != NULL && (Vertex::distance(*v, new_v) > MAX_MOVE_DISTANCE))
+	return
+
+    graph.do_vertex(x, y, NODE_SIZE);
 }

gamecore.h

@@ -38,9 +38,14 @@ class GameCore : public MainEvent
     // textures to draw
     SDL_Surface* background;
     SDL_Surface* node;
+    SDL_Surface* move_template;
 
     // data
     Graph graph;
+
+    // constants
+    static int NODE_SIZE;
+    static int MAX_MOVE_DISTANCE;
 };
 
 #endif

graph.cpp

@@ -11,7 +11,7 @@ using std::cerr;
 
 Graph::Graph()
 {
-    last_vertex = NULL;
+    current_vertex = NULL;
 }
 
 Graph::~Graph()
@@ -54,6 +54,29 @@ bool Graph::vertex_present(int x, int y, int size)
 	return false;
 }
 
+
+void Graph::do_vertex(int x, int y, int size)
+{
+    if (vertex_present(x, y, size)) select_vertex(x, y);
+    else add_vertex(x, y, size);
+}
+
+
+void Graph::select_vertex(int x, int y)
+{
+    for (list<Vertex*>::iterator cursor = vertices.begin();
+	 cursor != vertices.end(); cursor++)
+    {
+	Vertex* v = *cursor;
+	if (x >= v->x_min && x <= v->x_max && y >= v->y_min && y <= v->y_max)
+	{
+	    current_vertex = v;
+	    return;
+	}
+    }
+}
+
+
 void Graph::add_vertex(int x, int y, int size)
 {
     Vertex* v = new Vertex();
@@ -69,17 +92,17 @@ void Graph::add_vertex(int x, int y, int size)
 
     vertices.push_back(v);
 
-    if (last_vertex == NULL)
+    if (current_vertex == NULL)
     {
-	last_vertex = v;
+	current_vertex = v;
 	return;
     }
 
     Edge e;
-    e.a = last_vertex;
+    e.a = current_vertex;
     e.b = v;
     edges.push_back(e);
-    last_vertex = v;
+    current_vertex = v;
 }
 
 

graph.h

@@ -41,10 +41,14 @@ class Graph
     list<Vertex*> get_vertices() { return vertices; }
     list<Edge> get_edges() { return edges; }
 
-    void add_vertex(int x, int y, int size);
+    void do_vertex(int x, int y, int size);
+    Vertex* get_current_vertex() { return current_vertex; }
 
  private:
-    Vertex* last_vertex;
+    void add_vertex(int x, int y, int size);
+    void select_vertex(int x, int y);
+
+    Vertex* current_vertex;
     list<Vertex*> vertices;
     list<Edge> edges;
 };