1. Basics

1.1 How does it work?

We are about to make an animation by defining the locations and rotation angles of our main object at key moments; the instantaneous states thus generated are called animation keys. In order to define them, we will start with activating an object, simply by selecting it. At a given moment, set by the current Frame number, we will record the position and rotation angle of the object by striking the I-Key, and then we will choose, in the pop-up menu, the LocRot option. Then we will change the current Frame number, and for this new moment, we will give to our object new locations and rotation angles. Again, we will record them for this key moment, by striking the I-Key and by choosing, again, in the pop-up menu, the LocRot option. We will repeat all of this for as much animation keys as needed. Blender will then interpolate, for all the intermediate frames between the defined animation keys, the intermediate locations and rotation angles.

Frames and speed of the animation

There's obviously a strong tie between both of them. The speed of the animation can be set in the Rendermenu, in the Dimensions panel, in the Frame Range area with the FPS (frames per second) parameter. Thus, with the default value of FPS: 24, a frame "lasts" exactly 1/24th second. This means that when your animation is at the 24th frame, the animation already last one second; at the 48th frame, two seconds; at the 72th frame, three seconds, etc.Capture-01.png

1.2 How to define animation keys

Start with downloading the attached start file, unpack it and the open it within Blender. In the main menu, at the top of the window, you can select a Screen type among the classic prototypes: choose Animation.


You will especially locate the Graph Editor, the view in which the changes made through the use of the I-Key will be recorded, and where you would be able to make some edition on a later stage.


2. Setting the animation

2.1 Storing the initial state of the Cube

Select the Cube, and make sure that the Frame number is set to 1. i, the Timeline view, at the bottom of the Screen.


We will now insert the first key for the Frame number 1. Simply strike the I-Key. A pop-up menu appears, so that you could record the status of many available parameters. The Property panel (toggle N-Key) will highlight in yellow the Transform parameters of the Cube for this frame, to warn you that a key is set and that the Location and Rotation settings are currently constrained.


Hint: Setting keys for any parameter or setting in Blender

Thanks to the refactoring of Blender 2.50 and upper, every single parameter is animatable in Blender. If you want to animate a specific parameter, just use the Right-mouse button on the parameter in Blender's GUI, and select in the dropdown menu the most appropriate action you want. If you want to animate the Diffuse color of the Cube, for example, right click on the Diffuse colorband and select Insert Keyframes from the dropdown menu. The Graph Editor view is then updated to show the R, G and B Diffuse Colors of the selected object for the current frame.

Choose LocRot and pay attention to how the DopeSheet view and the Graph Editor view change. In the DopeSheet view, each frame for which a key has been added for the selected object will appear with a small mark. More inerestingly, in the Graph Editor view, function curves are drawn in order to match the Transformation parameters that have been captured by the I-Key. For now, there are only flat lines ; you can expand the tree in the Graph Editor view down to each individual function, like Z Location, X Euler Rotation, and such.


Six curves just appeared: 3 for Locations, and 3 for Euler Rotations. This is because the location of your object in a tridimensional space needs three componants (x, y and z) in order to be defined. The same for the rotation, three Euler angles (around the x axis, around the y axis and around the z axis) are needed in order to define its angular rotations in the same tridimensional space. However, you will note that these six curves are perfectly plane. This is because you have juste defined the initial state of your object (regarding its location and rotation) and that each individual value remains the same thorough the whole Timeline.

2.2 The cube at its apex

Now, jump to the Frame number 48 (with an animation set at a speed of 24 Frs/sec, the 48th Frame matches exactly with two seconds of animation). Toggle to the Right view (3-Numpad Key) and translate your object two units upward (G-Key, Z-Key and then optionnally hold the Ctrl-Key during your mouse movement in order to constrain it to entire values, or directly type in 2 while in Transform mode) and hit the Enter-Key in order to validate the new location.

Still in the same view, rotate your object by -180° around its X axis (R-Key, X-Key and then optionnally hold the Ctrl-Key during your mouse movement in order to constrain it to stepped rotation values, or directly type in -180 while in Transform mode) and strike the Enter-Key in order to validate the new rotation.


The cube is now slightly higher, floating in the middle of the air, and has rolled around itself, but this position has yet to be recorded as a key of the animation.

Press again the I-Key. In the pop-up menu, just like before, choose LocRot. Two out of the six curves from the Graph Editor view have just changed, and accordingly, new marks are now shown on the DopeSheet view for the Frame 48. The two updated curves are obviously the Z Location (the cube has been moved upward) and the X Euler Rotation (it also made a half-turn around itself).


2.3 Taking the cube back to the ground

Now jump to the Frame number 96 (another two seconds later, in our animation). Still in side view, translate your object two units downward (G-Key, Z-Key, -2 or hold the Ctrl-Key during the mouse transformation) and strike the Enter-Key in order to validate the new location. You can then use once again the I-Key, but this time, select only the Loc option, and pay attention to the changes in the Graph Editor view.


The cube is now back to the ground, and only the Z Location channel has been updated.

3. Extending the existing curves

The Graph Editor view is made of 3 parts: (1) The primary part is occupied by a graphic showing the curves, with the time (the Frame numbers of the animation) as the X-coordinate, and the value of the animated parameters as the Y-coordinate. (2) On the left vertical menu, you can see the list of all the chanels, the parameters keyed for animation. (3) In the header at the bottom of the view, you can sort the various types of chanels to display, by toggling on/off the small icons, or access specific functions through the menu entries.

3.1 Repeating ad nauseam the rise and descent of the cube

With the Z Location channel selected in the Graph Editor view, use the Key entry and then choose the Add F-Curve Modifier (or use Ctrl+Shift+M-Key combination) option. In the pop-up list of modifiers, select Cycles. From now on, its curve, which was depicting only a single rise and descent, will now continuously repeat this movement.


3.2 Setting the continuous rotation of the cube around its pitch axis

Now select the X Rotation channel in the Graph Editor view. Due to the high values of rotation angles, you will most probably have to zoom out a lot to see this curve with the two keys you set.

First of all, by default, the curve is interpolated between the keys using a Bezier Interpolation Mode. While this is ok for the cube translation movement (Bezier is fine for simulating some kind of damped movement), we would like the rotation speed to be perfectly constant over time: we have to choose the Linear Interpolation Mode (using the menu: Key > Interpolation Mode > Linear or Shift+T-Key).

Then, we can extend the straight line up to infinite by selection the Linear Extrapolation mode (using the menu: Key > Extrapolation Mode > Linear Extrapolation or Shift+E-Key). As we planned to extrapolate the initial line, this explains why we previously added only a Loc Key in §2.3.


Thanks to these two steps, we make sure that the rotation speed of the cube around the X axis will stay constant (the curve show a continuous slope) up to infinite.

It might sound unbelievable, but we are done with our animation!

4. Rendering the animation

At first, you have to specify the duration of the rendered animation. This could easily be done by setting the Start and End values in the Timeline view, at the bottom of our Screen. For our animation, if we want it to last 10 seconds with a FPS of 24, then we should set the End value to 240.


Hint: repeating playback of animation

Seamlessly repeating animation is tricky to figure out, but only the first time. For example, our animation starts on Frame 1 with the Cube laying on the ground. In Frame 192, it is exactly on the same position. If you render the animation from frames 1 to 192, and if you play repeatedly the animation, you will notice that the animation would "hang" during one frame, because the cube would virtually stay at the same position (on ground) two consecutive frames: No 192 of the previous play and No 1 of the next play. To avoid this, simply render your animation from frames 1 to 191.

Then you have to specify the dimensions of images rendered during the animation. This is discussed in the Dimensions panel in Render menu. Instead of fiddling yourself with the Resolution, you might find comfortable to use any of the Presets offered in the Dimensions panel. For example, the HDTV 720p preset should produce results interesting enough to be displayed on a modern TV.


Finally, the Output panel is the trickiest part, as it requires from you that you know what you want. By default, the File format is PNG which is good enough for rendering still images. Of course, an experimented Blender user knows how to convert a serie of still images using the Video Sequence Editor, but you can directly use more appropriate Movie file formats: AVI Jpeg, H.264, Xvid or Ogg Theora, for example. You can also select Ffmpeg that provides you with even more controls and Encoding formats. For simplicty's sake, please use any Free format available in the default Movie file format: Xvid or Ogg Theora.

In the Output panel, also make sure to specify the path to the directory where the rendered animation shoud be saved. Once done, you can use the Animation button in the Render panel, or simply use Ctrl+F12-Key to start rendering your animation.

That's it!

Article written on March the 8th, 2005.
Updated on July the 16th, 2010 for Blender 2.50 Alpha 2. Comments re-initialized.