Timelines & Triggers - Learn SpriteBuilder for iOS Game Development - page 133

spans the Timeline's full duration of 6 seconds. It should look like the one shown in Fig-
ure 5-3 .
Figure 5-3 . A Timeline animation of the Scale property with three keyframes
Caution If you were to animate the Scale property of a node that has physics
enabled, this would trigger an assertion in debug builds. The problem is that
one naturally assumes the physics shape would scale along with the node, but it
does not.
Editing Animation Settings
Okay, but how does the animation determine which values to interpolate? Right now,
nothing happens when you play this animation.
The important point here is that the keyframes allow you to edit the given property at the
given point in time. Right now, the Scale property is set to 1,1 for all keyframes, so even
though the animation runs, it doesn't alter the Scale property values.
With the doughnut image still selected, switch to the Item Properties tab. Then move the
Timeline Cursor back and forth anywhere between 0 and 6 seconds and notice how the
Scale property is grayed out most of the time. In fact, you can change the values of an an-
imated property only when the Timeline Cursor is exactly on top of a keyframe for the
given property.