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

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

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

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

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

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

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)

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.

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

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

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 …

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)