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Animation > Editing animation keys > Example: additive animation
Example: additive animation
This example uses additive animation to make a ball bounce up and down as it moves along a path. In the first animation, the sphere moves along a path on the ground; in the second animation, the sphere bounces straight up and down. When the bouncing animation is added to the path animation, the sphere bounces up and down as it moves along the path. By converting the bouncing animation into a reaction, you can let the surfer bounce the sphere as it moves along the path.
Create a sphere, a path, and a ground plane:
- Choose Modeling > Preset Surfaces > Sphere.
- Choose Modeling > Preset Surfaces > Horizontal Plane. Translate the plane along the Y axis so that the sphere sits on the ground.
- Choose Modeling > Draw Curve, and draw a curve in the Top viewport. In the curve geometry parameters, increase Steps to smoothen the curve.
Animate the sphere along the curve:
- Multi-select the sphere and the curve, in that order, and choose Animation > Path Animation.
- Go to time 0, and turn on Play. The sphere moves along the curve. Notice a path constraint animation appears in the Sequencer.
- Turn off the path animation while you create the bouncing animation. In the Sequencer, select the animation, then turn off Active in the Parameter Editor.
Create the bouncing animation with 3 position keys (down, up, down):
- Turn off Play and go to time 0.
- Select the sphere, turn on the Translate tool, and choose Animation > Add Animation Sequence.
A position animation appears in the Sequencer, with the first key at time 0. This is the first key with the sphere on the ground.
- Without moving the sphere, go to time 2, and press Ctrl+K to add a key. This is the third key, where the sphere is back on the ground.
- To create the up position key, turn on Record, go to time 1 and drag the sphere up 2 units in front view.
- In the Sequencer, drag the playhead to scrub the animation.
- Select a key to display the key values in the Parameter Editor, then set the keys to the following:
- Go to time 0 and turn on Play to preview the bouncing animation.
- Select the bounce animation, then in the Parameter Editor, set the Interpolation to Smooth, and turn on Cycle.
Now when you play the animation, the sphere bounces more smoothly, over and over again.
- In the Sequencer, double-click the animation sequence to display the animation curve. You can fine-tune the animation further by adding keys and adjusting the shape of the animation curve.
- To speed up the bouncing motion, increase the Time scale in the Parameter Editor.
Combine the bounce animation with the path animation:
- Select the path animation and turn on Active.
- Select the bounce animation and turn on Additive.
Turn on Play to preview the result. The sphere bounces up and down as it moves along the path.
Make the bounce interactive:
- Instead of bouncing on its own, make the sphere bounce when the surfer presses the Up arrow key. Select the bounce animation and turn off Cycle, then choose Interaction > Reactions > Play Animation.
- In the Interaction Editor, expand the ArrowKeySensor and link OnKeyPress:Up to the PlayAnim reaction.
Switch to Browse mode to test the interaction. Press the Up arrow key to make the sphere jump up.
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