4
我有一些問題,實現一個母親類的虛函數: 所以基本上我的代碼是:問題,實現虛擬功能
class Shape
{
public:
virtual ~Shape();
virtual bool Intersect (const Ray& ray, double& t) const =0;// to premit abstraktion (definition in sub-classes)
virtual Vector GetNormal(const Vector& at) const =0;
protected:
Color color;
double dc; //diffusive component
};
class Ball: public Shape
{
public:
Ball(const Color& col,const double diff,const double x,const double y,const double z,const double radius):
cx(x),cy(y),cz(z),r(radius)
{
Shape::color=col;
Shape::dc=diff;
assert(radius!=0);
}
virtual bool Intersect (const Ray& ray, double& t)
{
Vector c(cx,cy,cz), s(ray.xs,ray.ys,ray.zs);
Vector v(s-c);
double delta(std::pow(v*ray.dir,2)-v*v+r*r);
if(delta<0) return false;
const double thigh(-v*ray.dir+std::sqrt(delta)), tlow(-v*ray.dir-std::sqrt(delta));
if(thigh<0) return false;
else if (tlow<0){t=thigh; return true;}
else{t=tlow; return true;}
assert(false);//we should never get to this point
};
virtual Vector GetNormal(const Vector& at)
{
Vector normal(at - Vector(cx,cy,cz));
assert(Norm(normal)==r);// the point where we want to get the normal is o the Ball
return normal;
};
private:
// already have color and dc
double cx,cy,cz; //center coordinates
double r;//radius
};
,並在主球*球=新球(參數);
我收到以下消息「無法分配類型球的對象,因爲實現的funktions在球內是純的」。
我不明白爲什麼這是行不通的,因爲在子類中實現...
,傑克? – Shoe