1. Computer Graphics Imaging Ying Zhu Georgia State University
Lecture 18
Path Animation

2. Path animation Make an object follow a path Path animation steps
Benefit: may save the time of key framing
Path animation steps
Create a path, give it a name
Select the object
Add a “Follow Path” constraint to the object
Adjust parameters so that the object is aligned with the path orientation
Use “Speed” curve to control the path animation speed

3. Create a path In 3D view, press Space bar, add Curve  Path
You can also add a Bezier curve and then make it a path
Give the path a meaningful name
To extend a path
Go to Edit mode, select an end point on path
Either press E key (to extend), or ctrl + LMB
Can manipulate a path like any Bezier or NURBS curve

4. Create a path
In Editing (F9) panel, under “Curve and Surface”, you can change the number of frames for the path in “PathLen”

5. Add constraint
Select Object, in the Object (F7) panel, add a “Follow Path” constraint
In “Target OB” field, type in the name of the path
Press “CurveFollow” button

6. Align object with the path
Press N to bring up the “Transform Properties” window
Set LocX, LocY, and LocZ to 0.0, 0.0, 0.0
Set RotX, RotY, and RotZ to 0.0, 0.0, 0.0
This is important. Otherwise, the object may not be placed on the path.
In the “Constraint” panel, select the appropriate “Fw” and “Up” axis so that the object is aligned with the path
For example, the front end of the object should point to the forward direction of the path

7. Control the speed of path animation
By default the object will travel on the path at the same speed
You can add a Speed curve to vary the speed of path animation
For example, slow down the animation for uphill motion and speed up the animation for downhill motion (e.g. a roller coaster)

8. Speed curve Select the path in the 3D view
Go to IPO Curve editor, set IPO type to Path (default is Object), you’ll see a Speed curve
The vertical axis represents the percentage of the path
0.2 means 20% of the path, 1.0 means 100%, etc.

9. Speed curve
How to speed up the animation for certain segment of the path?
Drag the green vertical line to find the percentage number for the start point and end point of the segment
Add key points on the Speed curve for the start and end point of the segment
In edit mode, move these two key points closer to each other along the horizontal axis (don’t change their vertical values)
This means that it takes fewer frames to cover this segment of the path

10. Speed curve
How to slow down the animation for certain segment of the path?
Drag the green vertical line to find the percentage number for the start point and end point of the segment
Add key points on the Speed curve for the start and end point of the segment
In edit mode, move these two key points away from each other along the horizontal axis (don’t change their vertical values)
This means that it takes more frames to cover this segment of the path

11. Rotate the object on the path
You may want to rotate the object at certain point of the path
Play the animation with right arrow () key until the object reach the target location
Select and rotate the object
Press I to insert a key frame, and so on …

12. Camera path animation
You can animate a camera along a path to create dramatic camera motion
The process is the same as path animation with an object
Create a path
Add a “Follow Path” constraint to the camera
Press N, set LocX, LocY, LocZ to all 0, set RotX, RotY, RotZ to 0
Give camera an aim to track to (usually an empty object)