# TGraph2D, aspect ratio of axes

Hi,

I am drawing a TGraph2D using “LINE”, and I’d like to be able to interactively manipulate it in the TCanvas. Right now, if I grab-and-rotate, the aspect ratio of the three axes scales to fill the canvas. I’m drawing trajectories through space, so I’d like to be able to visualise the shape of the trajectory easily.

Can I somehow have it so that the aspect ratio is fixed, and the same in all directions, no matter how I rotate the view?

you can use a 3d polyline for that:

``````{
c1 = new TCanvas("c1","PolyLine3D & PolyMarker3D Window",200,10,500,500);

// Creating a view
TView3D *view = TView::CreateView(1);
view->SetRange(5,5,5,25,25,25);

// Create a first PolyLine3D
TPolyLine3D *pl3d1 = new TPolyLine3D(5);
pl3d1->SetPoint(0, 10, 10, 10);
pl3d1->SetPoint(1, 15, 15, 10);
pl3d1->SetPoint(2, 20, 15, 15);
pl3d1->SetPoint(3, 20, 20, 20);
pl3d1->SetPoint(4, 10, 10, 20);

// Create a first PolyMarker3D
TPolyMarker3D *pm3d1 = new TPolyMarker3D(12);
pm3d1->SetPoint(0, 10, 10, 10);
pm3d1->SetPoint(1, 11, 15, 11);
pm3d1->SetPoint(2, 12, 15, 9);
pm3d1->SetPoint(3, 13, 17, 20);
pm3d1->SetPoint(4, 14, 16, 15);
pm3d1->SetPoint(5, 15, 20, 15);
pm3d1->SetPoint(6, 16, 18, 10);
pm3d1->SetPoint(7, 17, 15, 10);
pm3d1->SetPoint(8, 18, 22, 15);
pm3d1->SetPoint(9, 19, 28, 25);
pm3d1->SetPoint(10, 20, 12, 15);
pm3d1->SetPoint(11, 21, 12, 15);
pm3d1->SetMarkerSize(2);
pm3d1->SetMarkerColor(4);
pm3d1->SetMarkerStyle(2);

// Draw
pl3d1->Draw();
pm3d1->Draw();
}
``````

Ok, that works, but can I also draw the axes?

`` view->ShowAxis();``

Nice, thanks!