bouncefun.cpp

C++&datastructure书籍源码,以前外教提供现在与大家共享

#include "canvas.h"
#include "randgen.h"
#include "dice.h"
#include "mathutils.h"

// illustrates iteration over all canvas objects by a shape/bouncer
// The MoleBouncer class bounces, but when a MoleBouncer object collides
// with a shape it removes itself and replaces itself by a MoleBouncer
// that's BLUE, located in the grid (0..WIDTH/10, 0..HEIGHT/10) of the
// canvas it's bouncing in, and travelling in close to the opposite direction
// namely 2*PI - angle

class MoleBouncer : public Bouncer
{
  public:
    MoleBouncer(Shape& s, double angle, double v)
     : Bouncer(s,angle,v)
   {  }
    
    Shape * clone()
    {
        return new MoleBouncer(*this);
    }
    virtual void update(AnimatedCanvas& ac)
    {
        RandGen rgen;
        Iterator<Shape> it(ac.makeIterator());
        bool collided = false;               // collision or still bouncing?
        Point p = getLocation();
        double angle = getAngle();
        for(it.Init(); it.HasMore(); it.Next())
        {   // check for collision, but not with myself
            if (it.Current().id() != this->id() && it.Current().overlaps(*this))
            {   ac.removeShape(this);
                ac.addShape(
                  new MoleBouncer(CircleShape(Point(rgen.RandReal(0,ac.width()/10),
                                                    rgen.RandReal(0,ac.height()/10)),
                                              RADIUS, CanvasColor::BLUE),
                                   2*PI - angle, 4));
                collided = true;
                break;
            }
        }
        if (!collided)           // no collision, update
        {   Bouncer::update(ac); 
        }
    }
    static int RADIUS;  // of new molecule/bouncer 
};

int MoleBouncer::RADIUS = 4;
 
class MakeBouncer : public MKAdapter
{
  public:
    MakeBouncer()
    { }
    void processClick(const Point& p, AnimatedCanvas& ac)
    {
        Dice d(6);
    
        CircleShape circ(p,d.Roll()*5, CanvasColor::MAGENTA);
        ac.addShape(new MoleBouncer(circ,2*PI/d.Roll(),d.Roll())); 
    }
};

int main()
{
    const int WIDTH=300, HEIGHT=200;
    AnimatedCanvas ac(WIDTH, HEIGHT, 20,20); 
    MakeBouncer mc;
    
    ac.addShape(mc);  
    ac.runUntilEscape(10);
    
    return 0;
}