canvas.Arrow(screenPos, screenPos + Vector<int>(e.vel * 10.0f));
cout << "entity: pos " << e.pos << ", vel " << e.vel << ", acc " << e.acc << endl;
canvas.Arrow(screenPos, screenPos + Vector<int>(e.vel * 10.0f));
cout << "entity: pos " << e.pos << ", vel " << e.vel << ", acc " << e.acc << endl;