Drawing Curves

To draw a curve, first you place the circle, then attach the legs.  If you do this right, the circle disappears and a curved track is generated between the leg segments.

To draw the circle:

1. Choose the Circle tool.
2. Press the mouse button near where you want the center of the circle.
3. Drag to adjust the circle's radius.
4. To move the circle instead of resizing it, press the Shift key as you drag.
5. Continue dragging, toggling the shift key as necessary, until the circle is where you want it; then release.

To draw the first leg:

1. Choose the Straight Track tool.
2. Position the cursor on the circle where you want the leg to join the curve.  The circle highlights.
3. While the circle is highlighted, press the mouse button.
4. Drag to where you want the other end of the leg.  While you drag one end, the other end adjusts automatically to remain tangent to the circle.

You can draw a leg in either direction, either starting on the circle or ending on it.  Just be sure that before you press or release the mouse button, the circle is highlighted so the segment will connect.

To complete the curve:

Draw the second leg as you did the first.  This time, when you release the mouse button, the circle disappears and the arc section between the two legs becomes a curve. 

When the train comes down one leg, it will go smoothly into and around the curve and exit on the other leg.

Notes

• All curves must be horseshoes.  That is, if you go clockwise from leg A onto the curve, then you must also go clockwise from the curve onto B.  In other words, when you draw the second segment, don't orient it backwards, as in the picture at right.
  
   
• Avoid crowds.  If you are working in a crowded area, and a track end happens to lie near the rim of a circle, then as soon as you draw the first leg to that circle, it will automatically form a curve with that track end. 

In the picture at right, when you draw the tangent segment at the top (green), the curve will automatically connect to the track end at A, whether you meant it to or not.

If this happens, Undo and try a different approach: draw the other leg first, or temporarily move the offending track end away from the circle.

• Watch the highlights.  If the curve doesn't form automatically after you release the second leg, it probably means you didn't get one leg close enough to the circle.  Be sure the circle is highlighted when you start or end drawing the leg segment.,