Curve Path

This entry will cover the use of a Curve called a Path, which can be used to guide an object to follow along its path.  A very obvious application for this is to create a roller coaster, which we will do for this example.

First add [SHIFT+A] a Path through the add Curve menu.  In Edit Mode [TAB], you can manipulate the curve by moving the control handles and extruding [E] points as necessary.  A vague idea of the shape of my coaster can be seen in the image below.

Next is the process of adding an object to follow the curve.  In this case I'll be using the Camera so that I can view a first person perspective of riding along the path.  Joining the two is done by parenting the object (i.e. Camera) to the curve, selecting both and [CTRL+P], and selecting Follow Path.

The time of the animation created by this can be controlled in the curve properties panel on the Path itself.  By default the animation length is 100 frames.

Note that the point at which the following object (camera) is attached to the curve will be based on the animation frame that is selected.  If frame 1 is selected, that will be connection reference point for the camera.

For fun, I created another curve in the shape of a slice of the track to give the track a physical presence.  The curve can be seen highlighted in the image below.

To apply it to the curve, select it in the Bevel Object box of the Geometry section in the Curve properties.

Finally, adding some support poles and a base floor, the track is complete, and the animation of the roller coaster can be run.  Note at certain curve points, the orientation of the following object may rotate, and so correction may be necessary with keyframes [I] on the following object.

Video of the roller coaster animation.