Help *lol*

[ravenheart]

o my god,

well i wrote a class called bat

Code: [Select]

class
{
Shape x;

...
}

and now i want my bat in main to be drawn, how can i tell the programm how to do it?

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RenderWindow App;
    App.Create(sf::VideoMode(800, 600, 32), "SFML Window", Style::Fullscreen);
bat left;
App.Draw(left);



surely will not work, but how can i do it?

[r1nux]

Have a "get-function" in the Bat-class?

Ex:

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class Bat
{
public:
...

sf::Shape getShape() { return m_shapeX; }

private:
sf::Shape m_shapeX;
}


sf::RenderWindow App;

...

Bat left;
App.Draw(left.getShape());

PS.
Havn't tested to compile this code.
But it's should give some kind of idea anyways.

[ravenheart]

well to have a little solution i added a function

Code: [Select]


Shape get()
{
return Shape;
}

App.Draw(bat.get());



it works but i doubt its best solution

[Laurent]

You can make bat inherit from sf::Drawable and override the Render virtual function to draw your shape, but then it will have its own position / rotation / scale / center, applied to everything it draws.
Sometimes it's useful, sometimes not

[r1nux]

You would probably want to send a reference instead of a copy of the shape
for performance.

[ravenheart]

i still wonder wheter i should use the heritage or like i did it now
add new functions

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bat.move(f x, f y)
{
polygon.Move(x,y);
}



what do u think?

[r1nux]

The overhead for calling one extra function is so small for simple games that
you wont notice it anyways.

But my 2 cents.
Try the both techniques to see what suits you the most.

[zarka]

well to have a little solution i added a function

Code: [Select]


Shape get()
{
return Shape;
}

App.Draw(bat.get());



it works but i doubt its best solution

you could also make a Draw function in the bat class

Code: [Select]


class Bat
{
public:
    void Draw(const sf::RenderWindow &rw) const
    {
        rw.Draw(shape);
    }
private:
    sf::Shape shape;
};


or have Bat inherit from Shape

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class Bat : public sf::Shape
{
public:
    void MySpecialFunc();
};


in the later example you can pass your Bat object to the Draw function of RenderWindow.

so what you need to ask your self is this. does bat have a shape, or is bat a shape. if it is a shape then inheritance is a good solution .. if it has a shape then composition would be the way to go. the rule is to generally prefer composition because inheritance will give you a overhead. usually not noticeable in small projects but still a good thing to keep in mind / know about.

EDIT: wow .. i was realy slow .. 3 posts between my click to ansawer and post

[ravenheart]

my problem is that i do programming only

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if( me == tired && girlfriend == not_here)

so i dont even have a plan what i want to do, at moment i only do some experiments and i dont know what i will need, to be on the safe side i decided to inherit

but i did

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class bat: public sf::Shape

could i have any problems with that coz laurent said to inherit sf::Drawable  ?

[zarka]

could i have any problems with that coz laurent said to inherit sf::Drawable  ?

depends on how Laurent have implemented sf::Shape if it has a virtual destructor it should be safe to inherit from.

if you inherit from sf::Drawable you will have to implement all the drawing yourself (using openGL). if you inherit from sf::Shape you also inherit Shapes render code meaning you do not need to implement it yourself

sdo i would say you definatly whant to inherit from sf::Shape.. and if that is unsafe you should go with composition

[ravenheart]

:cry:
i never understood virtual destructors, could u tell me how one could work with sf::shape?

edit: i do not understand ANY destructor

[r1nux]

:cry:
i never understood virtual destructors, could u tell me how one could work with sf::shape?

edit: i do not understand ANY destructor

By making the Base class Destructor virtual, both the destructors will be called in order.

One thing im confused about is that the shape-class dosnt declare
a default constructor.
Dosnt that mean that the shape-class gets a "regular" non-virtual destructor?

Edit:
Think of the destructor as the function that gets called when the object gets
destroyed or gets out of scope.

Example:

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class AClass
{
public:
AClass(); // Constructor
~AClass(); // Destructor
};


int main(int argc, char** argv)
{
AClass* testClass = new AClass; // Constructor gets called

delete testClass; // Destructor gets called

return 0;
}

or

int main(int argc, char** argv)
{
AClass testClass; // Constructor gets called

return 0; // Destructor gets called.
}

Class Reference

[ravenheart]

so far so good but what do i have to do??

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class bat: public Shape
{

bat();

...
~bat();
}


what should the funtion ~bat() look like ? somehow i should set the memory free how do i do that?

[quasius]

what should the funtion ~bat() look like ? somehow i should set the memory free how do i do that?

You need to delete any objects you new'd, or you get a memory leak.  If that doesn't make sense, google "c++ new delete."

[ravenheart]

as far as i know

new and delete are for dynamic memory;

im sorry bur i dont have any clue how i should use it in my class

when i create a bat

bat x;;
do i need to add some code concerning destruction?

and when i creat it by pointer?

bat *x = new bat;
do i have do add something like

~bat(){ x = NULL);  ?