Wie kann ich diese Liste funktionieren lassen?

Question

Ich versuche ein einfaches Spiel zu machen, indem ich nur Sechsecke benutze. Der std :: vector funktioniert jedoch aus irgendeinem Grund nicht. Es sollte eine Liste erstellen, aber es ist nur NULL? Was man ursprünglich tun sollte, ist das Hinzufügen von Trapazoiden, um eine Spur zu erzeugen. Von diesem Punkt an bewegt sich hauptsächlich die Kamera. Ich verwende derzeit ein Add On namens SFML und es wird hauptsächlich verwendet, um Bilder wie openGL zu erstellen.

/////////////////////////////////////////////////////////////////////////////////////////////////////////// 
#include <SFML\Graphics.hpp>   
#include <iostream> 
/////////////////////////////////////////////////////////////////////////////////////////////////////////// 
using namespace sf; 

int width = 1024; 
int height = 768; 
char title[] = "Racing"; 

int roadW = 2000; 
int segL = 200;    //segment length 
float camD = 0.84;   //camera debth 

int update(RenderWindow &w); 
void drawQuad(RenderWindow &w, Color c, int x1, int y1, int w1, int x2, int y2, int w2); 

/////////////////////////////////////////////////////////////////////////////////////////////////////////// 
struct Line 
{ 
    float x, y, z;   //segment length 
    float X, Y, W;   //screen cordinates 
    float scale; 

    Line() { x = y = z = 0; } 

    //from world to screen coordinates 
    void project(int camx, int camy, int camz) 
    { 
     scale = camD/(z - camz); 
     X = (1 + scale*(x - camx))*width/2; 
     Y = (1 - scale*(y - camx))*height/2; 
     W = scale * roadW * width/2; 

    } 
}; 


std::vector<Line> lines; //main track 
int N = lines.size(); 

/////////////////////////////////////////////////////////////////////////////////////////////////////////// 
int main() 
{ 
    std::cout << "Starting up... \n"; 
    std::cout << "Creating RenderWindow...(VideoMode(" << width << "," << height << "), " << title << "\n"; 
    RenderWindow window(VideoMode(width, height), title); 
    window.setFramerateLimit(60); 

    std::cout << "Creating std::vector<Lines> lines... \n"; 

    for (int i = 0; i < 1600; i++) 
    { 
     Line line; 
     line.z = i*segL; 
     lines.push_back(line); 
    } 

    std::cout << "Total Length[" << N << "]\n"; 

    std::cout << "\nRunning...\n"; 
    while (window.isOpen()) 
    { 
     if (update(window) != 0) return 0; 
    } 

    return 0; 
} 

int update(RenderWindow &w) 
{ 
    ///│LOGIC//// 
    ///└EVENTS/// 
    Event e; 
    while (w.pollEvent(e)) 
    { 
     if (e.type == Event::Closed) return 1; 
    } 

    ///│RENDER/// 
    ///├CLEAR//// 
    ///├ROAD///// 
    ///└CLEAR//// 
    w.clear(); 

    for (int n = 0; n < 300; n++) 
    { 
     Line &l = lines[n%N]; 
     l.project(0, 1500, 0); 

     Color grass = (n/3) % 2 ? Color(16, 200, 16) : Color(0, 154, 0); 
     Color rumble = (n/3) % 2 ? Color(255, 255, 2555) : Color(0, 0, 0); 
     Color road = (n/3) % 2 ? Color(107, 107, 107) : Color(105, 105, 105); 

     Line p = lines[(n - 1) % N]; 

     drawQuad(w, grass, 0, p.Y, width, 0, l.Y, width); 
     drawQuad(w, rumble, p.X, p.Y, p.W*1.2, l.X, l.Y, l.W*1.2); 
     drawQuad(w, road, p.X, p.Y, p.W, l.X, l.Y, l.W); 
    } 

    w.display(); 

    return 0; 
} 

void drawQuad(RenderWindow &w, Color c, int x1, int y1, int w1, int x2, int y2, int w2) 
{ 
    ConvexShape shape(4); 
    shape.setFillColor(c); 
    shape.setPoint(0, Vector2f(x1 - w1, y1)); 
    shape.setPoint(1, Vector2f(x2 - w2, y2)); 
    shape.setPoint(2, Vector2f(x2 + w2, y2)); 
    shape.setPoint(3, Vector2f(x1 + w1, y1)); 

    w.draw(shape); 
} 

Dank -Logan

Answer 1

Offenbar steht N für Null, weil am Anfang des Codes wird die Anzahl der Zeilen nicht bekommt, wann immer Sie es erfrischt rufen!