29 The Power of Inheritance and Polymorphism

Implementation: class Dungeon 1055int Dungeon::ClearSemiVertical(Pt p1, Pt p2, int max,Pt path[]){int ychange = p2.Y() - p1.Y();if(abs(ychange) > max) return 0;int xchange = p2.X() - p1.X();int deltax = (xchange > 0) ? 1 : -1;int deltay = (ychange > 0) ? 1 : -1;float slope = ((float)xchange)/((float)ychange);float error = slope*deltay;}int x = p1.X();int y = p1.Y();for(int i=0;i0.5) {x += deltax;error -= deltax;}error += slope*deltay;y += deltay;Pt p(x, y);if(!Accessible(p)) return 0;path[i] = p;if(p.Equals(p2)) return 1;}return 0;29.3.3 DungeonItemsDungeonItemClass DungeonItem implements a few basic behaviours shared by all variants. Itsconstructor sets the symbol used to represent the item and sets the link to theDungeon object. The body of the destructor is empty as there are no separateresources defined in the DungeonItem class.DungeonItem::DungeonItem(Dungeon *d, char sym){fSym = sym;fD = d;}DungeonItem::~DungeonItem() { }The Erase() and Draw() functions operate on the Dungeon object's main mapWindow. The call fd->Display() returns a Window* pointer. The Windowreferenced by this pointer is asked to perform the required operation.void DungeonItem::Erase(){