TowerDefense/tower.cpp

#include "tower.h"
#include <QPixmap>
#include <QVector>
#include <QPointF>
#include "bullet.h"
#include <QTimer>
#include "game.h"
#include "enemy.h"

extern Game *game;

Tower::Tower(QGraphicsItem *parent): QObject(), QGraphicsPixmapItem(parent) {
    setPixmap(QPixmap(":/images/tower.png"));

    // create points vectors
    QVector<QPointF> points;
    points << QPoint(1,0) << QPoint(2,0) << QPoint(3,1) << QPoint(3,2) << QPoint(2,3) << QPoint(1,3) << QPoint(0,2) << QPoint(0,1);

    // scale points
    int SCALE_FACTOR = 70;
    for (size_t i = 0, n = points.size(); i <n; i++) {
        points[i] *= SCALE_FACTOR;
    }

    // create a polygon from these points
    QPolygonF polygon(points);

    // create the QGraphicsPolygonItem
    attack_area = new QGraphicsPolygonItem(QPolygonF(points), this);

    // move the polygon
    QPointF poly_center(1.5, 1.5);
    poly_center *= SCALE_FACTOR;
    poly_center = mapToScene(poly_center);
    QPointF tower_center(x()+34, y()+64);
    QLineF ln(poly_center, tower_center);
    attack_area->setPos(x()+ln.dx(), y()+ln.dy());

    // connect timer to attack target
    QTimer *timer = new QTimer();
    connect(timer, SIGNAL(timeout()), this,SLOT(aquire_target()));
    timer->start(1000);

    attack_dest = QPointF(800,0);
}

double Tower::distanceTo(QGraphicsItem *item) {

    QLineF ln(pos(), item->pos());
    return ln.length();
}

void Tower::fire(){
    Bullet *bullet = new Bullet();
    bullet->setPos(x()+34, y()+64);

    QLineF ln(QPointF(x()+34, y()+64), attack_dest);
    int angle = -1 * ln.angle();

    bullet->setRotation(angle);
    game->scene->addItem(bullet);
}

void Tower::aquire_target() {

    QList<QGraphicsItem *> colliding_items = attack_area->collidingItems();

    if (colliding_items.size() == 1) {
        has_target = false;
        return;
    }
    double closest_dist = 300;
    QPointF closest_pt = QPointF(0,0);
    for (size_t i = 0, n = colliding_items.size(); i<n; i++) {
        Enemy *enemy = dynamic_cast<Enemy *>(colliding_items[i]);
        if (enemy) {
            double this_dist = distanceTo(enemy);
            if (this_dist < closest_dist) {
                closest_dist = this_dist;
                closest_pt = colliding_items[i]->pos();
                has_target = true;
            }
        }
    }

    attack_dest = closest_pt;
    fire();
}