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# Coordinate Container Class

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In the little tetris clone I'm building, I've been using the STL std::vector<int> to store lists of X-Y coordinate pairs so far (storing block shapes, etc.). Unless I'm mistaken (and correct me if I'm wrong here, please), sets and maps are not a good solution for this because they automagically sort new entries into the list. So, I've just come to the point in the code where I'm going to need to code in motion of the blocks, and I realized that it would be much more efficient if I created a custom template container class which derives from vector and stores pairs of values. That way, you could just code something like
Coord offset  ( 0, 1),
Position( 3, 4);

Position+=offset;
// Position is now (3,5)


with overloaded addition and subtraction operators and save yourself the overhead of typing the for loop to add them together every time. Now, I'm sure this is something that's been done before for both 2d and 3d (and better than my meager efforts can come up with). Is there something like this in the STL or somewhere similar that my beginner book isn't listing? Thanks, [Edited by - enigma555 on March 3, 2006 1:14:57 AM]

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... and if there isn't something readily available, can someone take a look at the header file I put together? I think all the functions are fairly evident from the comments.

/* X-Y Coordinate    Container Template Class   XY.h   my name */#ifndef XY_H#define XY_H#include <vector>#include <algorithm>template< class T >class XY{public:	// Constructors	XY( T = 0, T = 0 );         XY( std::vector<T> & );	XY( const XY<T> & );	// Overloaded additive operators	XY operator+( const XY<T> & );	XY operator-( const XY<T> & );	XY &operator+=( const XY<T> & );	XY &operator-=( const XY<T> & );		// Overloaded comparison operators	bool operator==( const XY<T> & ) const;	bool operator!=( const XY<T> & ) const;	// Get functions	XY<T> GetXY() const;	XY<T> GetCoords() const; 	T GetX() const;	T GetY() const;	T Get1st() const;	T Get2nd() const;	// Set functions	// Set both values entering a 2 element vector	bool SetXY( const std::vector<T> ); 	bool SetCoords( const std::vector<T> );	// Set first value from type <T>	void SetX( const T );	void Set1st( const T );	// Match first value from input coordinate	void SetX( const XY<T> & );	void Set1st( const XY<T> & );	// Set second value from type <T>	void SetY( const T );	void Set2nd( const T );	// Match second value from input coordinate	void SetY( const XY<T> & );	void Set2nd( const XY<T> & );	private:	std::vector< T > Coords;};#endif

Anything I should add or am doing inefficiently? I doubled up the set and get functions to help avoid confusion if working in a different coordinate system (like the row/column coord system I'm using for the tetris clone).

[Edited by - enigma555 on March 3, 2006 1:34:33 AM]

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Quote:
 Original post by enigma555... and if there isn't something readily available, can someone take a look at the header file I put together? I think all the functions are fairly evident from the comments.*** Source Snippet Removed ***Anything I should add or am doing inefficiently? I doubled up the set and get functions to help avoid confusion if working in a different coordinate system (like the row/column coord system I'm using for the tetris clone).
Basically you're implementing what's usually called a 'vector' class. (Just to avoid confusion, such classes are different than the stl vector in that they deal with a vector of values in a geometric sense.) There are countless such classes out there; just about everyone has written his or her own, and they can be found online in various libraries and in professional source code (try the Doom 3 sdk, for example). A google for 'vector class' should turn up quite a few hits.

Your class will probably work (especially for a simple Tetris game), but there are various issues with nomenclature and efficiency that you'll want to address if you use it for anything more demanding. I think the easiest thing to do would be to look around a bit and see what other people have done, which I'm guessing will give you many ideas for possible improvements (IMO).

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Quote:
 Original post by jykI think the easiest thing to do would be to look around a bit and see what other people have done, which I'm guessing will give you many ideas for possible improvements (IMO).

One of which would possibly re-thinking making it a template class. Because then, if I wanted to, I could make an XY<std::list<int> > object.

If you want to keep it that way, no problem since at this stage you'll probably be the only one using it. Personally I've kept my Vector3d class just floats. You could always leave the class as a template and then just make a couple of typedefs.
typedef XY<float> XYf;typedef XY<int> XYi;

Or something like that.

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Quote:
 Original post by EndarOne of which would possibly re-thinking making it a template class. Because then, if I wanted to, I could make an XY > object.

I actually was going to create it as an <int> and turned it into a template so I could easily port it to <float>. There are only specific locations that the blocks can hold, so <int> seems more natural to me.

Thanks for your comments, guys. I'll rummage around and see what others have done.

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