Baking is a fundamental technique in the world of 3D animation, allowing you to convert dynamic simulations or animations into keyframes. By learning this process, you get the ability to easier transfer animations to other software.

To bake a rigid body animation, select the animated object(s) and go to the Object dropdown at the top left of the 3D viewport. From this dropdown, select Animation > Bake Action. In the available popup, set the starting and ending frames as well as the frame step and any other settings you require. To bake the animation, press OK.

To bake a physics simulation, select the domain of the simulation and go to the Physics tab in the Properties panel. Go to Field > Cache and select an output folder for the simulation to be baked to. Set a starting and ending frame and set the Type to All. Enable the Is Resumable checkbox in case you'd like to pause the bake at any point. Press Bake All to bake the simulation. To delete the bake, press Free All.

Now let's take a deeper dive into why you would want to bake an animation and what type of animations you can use it for.

Why bake an animation or simulation to keyframes

By converting animations to keyframes, you optimize performance, especially for resource-intensive simulations.

Pre-calculating and storing animation data results in smoother playback and faster rendering, even in complex scenes. Baking simulations to keyframes frees up computational resources and eliminates the need for continuous recalculations.

This means that you can iterate on the animation without waiting for simulations to run each time, saving time and improving efficiency.

How to bake an animation to keyframes in Blender?

If you have an object that is animated using drivers or even rigid body simulations, baking the animation is quite straightforward.

Start by creating or setting up the animation you want to bake. As an example, let's consider a scenario where a sphere is moving along the Y-axis, following a sine wave pattern. To achieve this, select the sphere object and add a keyframe to its Y-location property at frame 1. In the input field for the Y-location, enter the following function: #sin(frame/(2*pi)). Playing the animation now shows the sphere cycling from left to right along the Y-axis.

Alternatively, the following steps outlining how to bake an animation also apply for rigid body simulations as well:

• With the animated object selected, go to the Object menu in the 3D viewport header, then navigate to Animation > Bake Action from the dropdown menu.

• In the "Bake Action" panel that appears, you can customize the settings according to your needs. Ensure that the "Bake to" option is set to "Keyframes." This tells Blender to bake the animation into keyframes. You can adjust the start and end frames to define the range of the animation you want to bake. For our example, set the start frame to 1 and the end frame to 250.

• Once you have configured the settings, click the "OK" button to initiate the baking process. Blender will calculate the animation and convert it into keyframes.
• Each baked keyframe can now be seen on the timeline and can be selected and deleted or manipulated to your liking.

Optionally, you can also adjust the Frame Step property in the bake settings. This setting allows you to control the interval between keyframes when baking an animation for an object. By specifying a frame step value, you can determine how frequently keyframes will be generated during the baking process.

For instance, if you set the frame step to 2, every other frame will be baked as a keyframe, effectively reducing the overall keyframe density.

How to bake a fluid simulation to keyframes?

Baking a fluid, smoke, or fire simulation to keyframes requires a slightly different approach than outlined above. This is because these simulations are more complex than rigid body simulations. For this reason, Blender provides specialized systems to handle these simulations.

Let's first set up an example simulation:

• Add a new sphere and go to the Object menu in the header of the 3D viewport. From here, select Quick Effects > Quick Liquid in order to set up a simple fluid simulation.
• Select the sphere and head to the Physics Properties tab. Here, under Fluid Settings, set the Flow Behavior to Inflow so that the liquid is flowing continuously rather than having a small fixed volume.
• Press play on the timeline (or press spacebar) to now view your simulation.

You will notice that, for most devices, this is a rather simple simulation that runs smoothly, and hence you might not consider needing to bake the simulation. Still, it is a good habit to bake the simulation in order to get even faster playback. So let's now bake the simulation:

• Select the liquid domain of the simulation while in object mode. This is generally the extra cube that has automatically been added while creating the Quick Liquid.
• Head to the Physics Properties tab and go to the Fluid > Cache settings.
• Select the output folder for the bake to be saved to.
• Change the cache Type to 'All' - this allows you to bake the entire simulation with the press of a single button.
• Optionally, enable the 'Is Resumable' checkbox. This allows you to pause the bake by pressing the ESC key and resuming it at a later time, instead of needing to delete the bake and recreating it entirely. This might save you some time with more complex simulations that might require minor changes during the bake.
• Next, press Bake All and wait for the bake to finish.
• The Bake All button has now changed to Free All. This option can now be used if you need to delete the bake and bake the simulation again, in case any changes are made to the simulation settings.

These same steps can also be applied to any other physics simulation, such as an object with smoke or fire.

Final thoughts

We have gone over the simple steps of baking rigid body animations or any other fire, smoke, or liquid simulations in Blender. Even with simpler animations that don't require many resources, it is always a good habit to bake a simulation to keyframes. This especially applies for cases where you might want to manually change how the animation looks for a few specific frames, as this can't be done when using physics or drivers to animate your objects.

Thanks for reading and start animating!