Tut 12

CMakeLists.txt

@@ -22,6 +22,7 @@ set(PROJECT_SOURCES
         game.h game.cpp
         res.qrc
         bullet.h bullet.cpp
+        enemy.h enemy.cpp
 )
 
 if(${QT_VERSION_MAJOR} GREATER_EQUAL 6)

enemy.cpp

@@ -0,0 +1,51 @@
+#include "enemy.h"
+#include <QTimer>
+
+
+Enemy::Enemy(QGraphicsItem *parent) {
+    //set graphics
+    setPixmap(QPixmap(":/images/enemy.png"));
+
+    //set points
+    points << QPointF(200,200) << QPointF(400,200);
+    point_index = 0;
+    dest = points[0];
+    rotateToPoint(dest);
+
+    QTimer * timer = new QTimer();
+    connect(timer, SIGNAL(timeout()), this, SLOT(move_forward()));
+    timer->start(150);
+
+
+}
+
+void Enemy::rotateToPoint(QPointF p) {
+    QLineF ln(pos(), p);
+    setRotation((-1 * ln.angle()));
+
+}
+
+void Enemy::move_forward() {
+    //if close to dest, rotate to next dest
+    QLineF ln(pos(), dest);
+    if (ln.length() < 5) {
+        point_index++;
+        if (point_index >= points.size()) {
+            return;
+        }
+        dest = points[point_index];
+        rotateToPoint(dest);
+    }
+
+    int STEP_SIZE = 5;
+    int theta = rotation(); // degrees
+    double dy = STEP_SIZE * qSin(qDegreesToRadians(theta));
+    double dx = STEP_SIZE * qCos(qDegreesToRadians(theta));
+
+    setPos(x()+dx, y()+dy);
+}
+
+
+
+
+

enemy.h

@@ -0,0 +1,25 @@
+#ifndef ENEMY_H
+#define ENEMY_H
+#include <QGraphicsPixmapItem>
+#include <QObject>
+#include <QList>
+#include <QPointF>
+
+
+
+class Enemy: public QObject, public QGraphicsPixmapItem {
+    Q_OBJECT
+public:
+    Enemy(QGraphicsItem *parent=0);
+    void rotateToPoint(QPointF p);
+public slots:
+    void move_forward();
+
+private:
+    QList<QPointF> points;
+    QPointF dest;
+    int point_index;
+
+};
+
+#endif // ENEMY_H

game.cpp

@@ -2,6 +2,7 @@
 #include <QGraphicsScene>
 #include "tower.h"
 #include "bullet.h"
+#include "enemy.h"
 
 Game::Game(): QGraphicsView() {
     scene = new QGraphicsScene(this);
@@ -18,6 +19,10 @@ Game::Game(): QGraphicsView() {
     setFixedSize(800,600);
     setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
     setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
+
+    // create enemy
+    Enemy *enemy = new Enemy();
+    scene->addItem(enemy);
 }
 
 void Game::mousePressEvent(QMouseEvent *event) {

res.qrc

@@ -2,6 +2,7 @@
     <qresource prefix="/images">
         <file>tower.png</file>
         <file>missile.png</file>
+        <file>enemy.png</file>
     </qresource>
     <qresource prefix="/"/>
 </RCC>

tower.cpp

@@ -5,6 +5,7 @@
 #include "bullet.h"
 #include <QTimer>
 #include "game.h"
+#include "enemy.h"
 
 extern Game *game;
 
@@ -37,13 +38,19 @@ Tower::Tower(QGraphicsItem *parent): QObject(), QGraphicsPixmapItem(parent) {
 
     // connect timer to attack target
     QTimer *timer = new QTimer();
-    connect(timer, SIGNAL(timeout()), this,SLOT(attack_target()));
+    connect(timer, SIGNAL(timeout()), this,SLOT(aquire_target()));
     timer->start(1000);
 
     attack_dest = QPointF(800,0);
 }
 
-void Tower::attack_target() {
+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);
 
@@ -53,3 +60,29 @@ void Tower::attack_target() {
     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();
+}

tower.h

@@ -10,11 +10,15 @@ class Tower : public QObject, public QGraphicsPixmapItem {
     Q_OBJECT
 public:
     Tower(QGraphicsItem *parent=0);
+    double distanceTo(QGraphicsItem *item);
+    void fire();
 public slots:
-    void attack_target();
+
+    void aquire_target();
 private:
     QGraphicsPolygonItem *attack_area;
     QPointF attack_dest;
+    bool has_target;
 };
 
 #endif // TOWER_H