Changing Walking Style

First we derive a new class from Boy and update the walking style:

#include <boy.h>

class BoyEx : public Boy

{

public :

BoyEx () : Boy ()

{

}

void GoesTo ( double dX, double dY, double dDuration,

double dStepDuration = 1 )

{

double dStartTime = GetTime (); // remember start time

SetPos ( GetX (), GetY () ); // initial control point

// lets split a step into 4 stages

for ( int i=0; i<dDuration * 4 / dStepDuration; i++ )

{

// set time for current stage

SetTime ( dStartTime + i * dStepDuration / 4 );

// if this is a first stage

if ( i%4 == 0 )

{

LeftLeg.SetShift ( 0, 0 );

LeftLeg.SetAngle ( 0 );

RightLeg.SetShift ( 0, 0 );

RightLeg.SetAngle ( 0 );

continue ;

}

// if this is a second stage

if ( i%4 == 1 )

{

LeftLeg.SetShift ( 0, -30 );

LeftLeg.SetAngle ( - 45 );

RightLeg.SetShift ( 0, 0 );

RightLeg.SetAngle ( 0 );

continue ;

}

// if this is a third stage

if ( i%4 == 2 )

{

LeftLeg.SetShift ( 0, 0 );

LeftLeg.SetAngle ( 0 );

RightLeg.SetShift ( 0, 0 );

RightLeg.SetAngle ( 0 );

continue ;

}

// if this is a fourth stage

if ( i%4 == 3 )

{

LeftLeg.SetShift ( 0, 0 );

LeftLeg.SetAngle ( 0 );

RightLeg.SetShift ( 0, -30 );

RightLeg.SetAngle ( - 45 );

}

}

// ending control point

SetTime ( dStartTime + dDuration );

SetPos ( dX, dY );

LeftLeg.SetShift ( 0, 0 );

LeftLeg.SetAngle ( 0 );

RightLeg.SetShift ( 0, 0 );

RightLeg.SetAngle ( 0 );

}

};

void Scene1 ()

{

Image Back ( "backgrounds/house.svg" );

Back.SetVisible ( true );

BoyEx Max;

Max.SetVisible ();

Max.SetPos ( 300, 290 );

Max.GoesTo ( -300, 290 , 5 );

}

If you compile the above example you will see that walking style is changed and Boy bends his legs when walking and does not move his hands at all:

Although we have created a new sub-class for Boy, the Boy class is unchanged and can also be used to instantiate “boys” who will swing their arms when walking.