Problem with shooting bullet from rectangle in different angle

BeastBook

Hi i created QGraphicsRectItem and with size 100 x100 and bullet 10 x50
problem is when i rotate my rect i want to shoot in different way not always in 90 degrees.I tried by creating MyRect object from my class MyRect and get current positions but it doesn't work .The goal is when rect is rotated shoot bullet in correct angle

void Bullet::move()
{

//checking collision



QList <QGraphicsItem *>colliding_items = collidingItems();
for(int i=0,n=colliding_items.size();i<n;i++)
{
    if(typeid (*(colliding_items[i]))==typeid (Enemy))
{
           //remove them both
        scene()->removeItem(colliding_items[i]);
        scene()->removeItem(this);

        //delete from heap
        delete colliding_items[i];
        delete this;
        return;
}
}

//here is problem
/*************************/
if(y()>200)
setPos(x()+10,y()-10);

       else

     setPos(x(),y()-10);

/****************************/

if(pos().y() + rect().height() < 0)
{
    scene()->removeItem(this);
    delete this;
    qDebug() << "Bullet deleted";

}

}

KillerSmath

@BeastBook
Use mapToScene(qreal x, qreal y) to get the translated point with rotation transformation.

setPos(mapToScene(0, -5));

BeastBook

@KillerSmath I tried but it didn't work still while i rotate my rect bullet goes with same angle

KillerSmath

@BeastBook
Can you show more detail of how you are implementing your Bullet Class ?

BeastBook

Bullet::Bullet()
{

//dimensions of the bullet
setRect(0,0,10,50);

/


QTimer *timer = new QTimer();
connect(timer,SIGNAL(timeout()),this,SLOT(move()));

timer->start(50);

}

void Bullet::move()
{

//check collision

MyRect *rect1= new MyRect();



QList <QGraphicsItem *>colliding_items = collidingItems();
for(int i=0,n=colliding_items.size();i<n;i++)
{
    if(typeid (*(colliding_items[i]))==typeid (Enemy))
{
           //remove them both
        scene()->removeItem(colliding_items[i]);
        scene()->removeItem(this);

        //delete from heap
        delete colliding_items[i];
        delete this;
        return;
}
}





//moving bullet








setPos(mapToScene(0,-5));








/*check if the bullet is out or range
if(pos().y() + rect().height() < 0)
{
    scene()->removeItem(this);
    delete this;
    qDebug() << "Bullet deleted";

}

}

Now MyRect class

void MyRect::keyPressEvent(QKeyEvent *event)
{

if(event->key()==Qt::Key_Left)
{




 setTransformOriginPoint(QPoint(50,50));
  setRotation(rotation()-10);






  

}

else if(event->key()==Qt::Key_Right)
{


    setTransformOriginPoint(QPoint(50,50));
    setRotation(rotation()+10);

  

}


else if (event->key()==Qt::Key_Space) {


    Bullet *bullet = new Bullet();
    qDebug() << "Bullet created";
    bullet->setPos(x()+50,y()-5);
    scene()->addItem(bullet);

}

}

and this is main , enemy class is fine

QGraphicsScene *scene = new QGraphicsScene();



MyRect *player  = new MyRect();


player->setRect(0,0,100,100);  


//add player to scene
scene->addItem(player);


player->setFlag(QGraphicsItem::ItemIsFocusable); 
player->setFocus();


QGraphicsView *view  = new QGraphicsView(scene); //adding scene on view

//lock scrollbar
view->setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
view->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);

view->show();  

view->setFixedSize(800,600);
scene->setSceneRect(0,0,800,600); /*SetRect on scene point 0 0 size 800x600*/

//setting position of player
player->setPos(view->width()/2,view->height()/2);


//creating enemy
QTimer *timer = new QTimer();
QObject::connect(timer,SIGNAL(timeout()),player,SLOT(spawn()));
timer->start(2000);

KillerSmath

@BeastBook
Okay, you are creating the Bullet on below code

else if (event->key()==Qt::Key_Space) {
    Bullet *bullet = new Bullet();
    qDebug() << "Bullet created";
    bullet->setPos(x()+50,y()-5);
    scene()->addItem(bullet);
}

However, where were you change the rotation of this bullet to the same rotation of the player ?

BeastBook

@KillerSmath That should be in metod in Bullet class void move() where i put your code setPos(mapToScene(0,-5));

void Bullet::move()
{

MyRect *rect1= new MyRect();



QList <QGraphicsItem *>colliding_items = collidingItems();
for(int i=0,n=colliding_items.size();i<n;i++)
{
    if(typeid (*(colliding_items[i]))==typeid (Enemy))
{
           //remove them both
        scene()->removeItem(colliding_items[i]);
        scene()->removeItem(this);

        //delete from heap
        delete colliding_items[i];
        delete this;
        return;
}
}





setPos(mapToScene(10,0));






if(pos().y() + rect().height() < 0)
{
    scene()->removeItem(this);
    delete this;
    qDebug() << "Bullet deleted";

}

}

Also i try this way in metod move ()
get rect x and y axis

and set rotation position
setPos(rect1->pos().x() ,rect1->pos().y());
size of scene is 800x600 and i center my rect with 100x100 at the half 400x300

KillerSmath

@BeastBook
You have misunderstand me, i told about the rotation when the bullet is created.
The Bullet will be create on front of player and move in same direction of rotation of player when the bullet is created.

See snippet of code to understand how it would be implemented.

else if (event->key()==Qt::Key_Space) {
    Bullet *bullet = new Bullet();
    qDebug() << "Bullet created";
    bullet->setPos(mapToScene(50, -5)); // use MapToScene to get the translated position of player with rotation transformation
   bullet->setRotation(rotation()) // set the bullet rotation to the same rotation of the player when the bullet is created
    scene()->addItem(bullet);
}

The setPos call on Bullet Move function is just to keep moving itself. However, if you don't rotate it to the same direction of player, it will be move to a default direction.

BeastBook

@KillerSmath Thank you very much now i understand this

One more thing how to implement in my function to go to the end with this angle when i shoot

BeastBook

I solve it i put in my move method function adnvance (int phase)

if(!phase) return;

    QPointF location = this->pos();

    setPos(mapToParent(0,-(5)));

Thank you again

KillerSmath

@BeastBook
Do not confuse mapToParent with mapToScene. The value of mapToParent is only equal to mapToScene if the object has not a parent because the default parent is the scene.

So, if every issues have been solved, mark this topic as Solved.