
The best way to think of Paper 2D Flipbooks (or Flipbooks for short) is in the form of hand-drawn animation, where a series of images that are slightly different are "flipped" through to produce what appears to be motion. In Unreal Engine, Flipbooks consist of a series of keyframes, each of which contains a Sprite to be displayed and a duration (in frames) to display it. A Frames Per Second option determines how fast the frames will be displayed, indicating how many animation "beats" will occur in a second and the keyframes themselves can be edited in the Details panel or by using a Timeline which can be found at the bottom of the Flipbook Editor.
Creating a Flipbook
There are a couple of ways you can go about creating a Flipbook. You can either create a blank Flipbook that you populate with sprites yourself or you can auto-generate a Flipbook based off a series of selected sprites.
You can import a JSON-formatted sprite sheet description, which will import associated textures and create sprites and a Flipbook for the described frames as well. See Paper 2D Import Options for more information.
Blank Flipbooks
Creating a blank Flipbook can be achieved by following the steps below.
From the Content Drawer:
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Click the +Add button, then in the context menu under Animation, select the Paper Flipbook option.
You can also Right-click inside the Content Drawer to open the context menu instead of clicking Add New.
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You will then be prompted to enter a name for your new Flipbook.
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After you select a name, your Flipbook asset has been created.
The asterisk symbol in the lower-left corner indicates that the asset has not been saved yet and will go away when you save it.
Auto-Generated Flipbooks
To create an automatically generated Flipbook, follow the steps below.
From the Content Drawer:
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Locate and select each of the sprites you would like to include in the Flipbook in the Content Drawer.
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Right-click on any of the sprites, then select the Create Flipbook option from the context menu.
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You will then be prompted to enter a name for your new Flipbook.
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After you select a name, your Flipbook asset has been created.
When you mouse over the Flipbook in the Content Drawer, you will also be able to preview the Flipbook animation.
When auto-generating a Flipbook, the naming convention you use for the sprites included is very important as the sprites will be added to the Flipbook in alphabetical order. In the example above, we've named each of our sprites for creating an Idle to Idle_x where X is the order in which we want the sequence to appear.