3D Shape Code in C ++

Here is the complete program listing.

The result is a rotating red star following the cursor. Written without OpenGl.

Explain to me a couple of points.

There is unit1.h in it there is a trace. strings, and what do they mean?

class TForm1 : public TForm { __published: TTimer *Timer1; void __fastcall FormMouseMove(TObject *Sender, TShiftState Shift, int X, int Y); void __fastcall FormMouseWheel(TObject *Sender, TShiftState Shift, int WheelDelta, TPoint &MousePos, bool &Handled); private: // User declarations public: // User declarations __fastcall TForm1(TComponent* Owner); void DrawPoints(); SortTriangles(); Graphics::TBitmap*BackBuffer; }; 

PS on the form there is a timer that is responsible for the rotation of the shape.

Next, what's the z-buffer? and generally where about him read the sensible material?

Then it is not clear the last lines in the listing, namely these:

 void TForm1::DrawPoints() { TFPoint point1,point2,point3; BackBuffer->Canvas->Brush->Color=clBlack; BackBuffer->Canvas->FillRect(Form1->GetClientRect()); BackBuffer->Canvas->Brush->Color=clRed; BackBuffer->Canvas->Pen->Color=clOlive; BackBuffer->Canvas->Pen->Width=1; TPoint p[3]; SortTriangles(); for(int i=0;i<TrCol;i++) { point1=XYZtoXY(StarPoints[Triangles[i].p1].X,StarPoints[Triangles[i].p1].Y,StarPoints[Tri angles[i].p1].Z); point2=XYZtoXY(StarPoints[Triangles[i].p2].X,StarPoints[Triangles[i].p2].Y,StarPoints[Triangles[i].p2].Z); point3=XYZtoXY(StarPoints[Triangles[i].p3].X,StarPoints[Triangles[i].p3].Y,StarPoints[Triangles[i].p3].Z); p[0].x=point1.X; p[0].y=point1.Y; p[1].x=point2.X; p[1].y=point2.Y; p[2].x=point3.X; p[2].y=point3.Y; BackBuffer->Canvas->Polygon(p,2); } Canvas->Draw(0,0,BackBuffer); } //--------------------------------------------------------------------------- void __fastcall TForm1::FormMouseMove(TObject *Sender, TShiftState Shift, int X, int Y) { rotation-=(X-oldX)/50.0; plane-=(Y-oldY)/100.0; DrawPoints(); oldX=X; oldY=Y; } //--------------------------------------------------------------------------- void __fastcall TForm1::FormMouseWheel(TObject *Sender, TShiftState Shift, int WheelDelta, TPoint &MousePos, bool &Handled) { distance+=WheelDelta/1000.0; DrawPoints(); }