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Re: New graph packages [message #35603 is a reply to message #35601]

Sun, 04 March 2012 13:48

Didier
Messages: 680
Registered: November 2008
Location: France

Contributor

Hi Koldo,

I think DataSource used in ScatterDraw should go template:

The only reason for this is to enable high performance if needed:

class DataSource {
public:
	typedef double (DataSource::*Getdatafun)(int id);

	DataSource() : isParam(false) {}
	virtual ~DataSource() {};	
	virtual double z(int id) 	{return Null;};
	virtual double y(int id) 	{return Null;};
	virtual double x(int id) 	{return Null;};
	virtual int GetCount()		{return Null;};
	bool IsParam()				{return isParam;};

	virtual double MinX() {return Min(&DataSource::x);}	
	virtual double MinY() {return Min(&DataSource::y);}	
	virtual double MinZ() {return Min(&DataSource::z);}	

	virtual double MaxX() {return Max(&DataSource::x);}				
	virtual double MaxY() {return Max(&DataSource::y);}	
	virtual double MaxZ() {return Max(&DataSource::z);}	

	virtual double AvgX() {return Avg(&DataSource::x);}	
	virtual double AvgY() {return Avg(&DataSource::y);}					
	virtual double AvgZ() {return Avg(&DataSource::z);}

Class DataSource is a pure virtual class
==> so all method calls need to go by the virtual table ==> poor performance
This is specially true for the x,y,z methods which get called for each point drawn.

If Scatter Draw had was defined the following way:

template<class DATASOURCE = DataSource>
class ScatterDraw {
public:
...

The following high performance trivial class could be used intead:

template<int NBPOINTS>
class DataSource {
private:
	double _x[NBPOINTS];
	double _y[NBPOINTS];
	double _z[NBPOINTS];
public:

DataSource() {}
inline double z(int id) 	{return _x[id];}
inline double y(int id) 	{return _y[id];}
inline double x(int id) 	{return _z[id];}
inline int GetCount()		{return NBPOINTS;}
inline bool IsParam()		{return false;}

inline double MinX() {return ....;}	
inline double MinY() {return ....;}	
inline double MinZ() {return ....;}	

inline double MaxX() {return ....;}				
inline double MaxY() {return ....;}	
inline double MaxZ() {return ....;}	

inline double AvgX() {return ....;}	
inline double AvgY() {return ....;}					
inline double AvgZ() {return ....;}	
};

The backdraw to this is that most of ScatterDraw should go in the header
But after all that is not such a big issue.

NB: I know that most of the performance is due to drawing speed but all enhancements are welcome I think

What do you think ?

[Updated on: Sun, 04 March 2012 14:42]

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