For Blender: 2.33 - Version française disponible(fr)

::Basics::

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 Scene menu (F10 key), in the Format tab and the Frs/sec (frames per second) parameter. Thus, with the default value of 25 Frs/sec, a frame "lasts" exactly 1/25th second. This means that when your animation is at the 25th frame, the animation already last one second; at the 50th frame, two seconds; at the 75th frame, three seconds, etc.

::How to define animation keys::

Start with downloading the starting file, unpack it and the open it within Blender. You will pay attention, on the upper left corner of the screen, to the IPO Curve Editor window. This is where the changes made through the use of the I key will be recorded, and could be edited later. In the Scene menu (F10 key) and in the Format tab, you will note that we set the speed of animation to 24 Frs/sec.

scene-format-settings

Select the cube, and make sure that the Frame number is set to 1.>

3Dview-frame-01

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. Choose LocRot and pay attention to how the IPO Curve Editor window changes.

IPO-curve-editor

Six curves just appeared: 3 for Loc, 3 for Rot. This is because the location (Loc) of your object in a tridimensional space needs three componants (x, y and z) in order to be defined. The same for the rotation (Rot), three 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).

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 side view (3 key from the num pad) and translate (G key) your object two units upward (keep the CTRL key pressed during this operation) and strike the ENTER key in order to validate the new location.

Still in the same view, rotate (R key) your object by -180° around its origin and strike the ENTER key in order to validate the new rotation.

3dview-frame-48

Now, strike again on the I key. In the pop-up menu, just like before, choose LocRot. Two out of the six curves from the IPO Curve Editor window have just changed.

IPO-frame-48

Now jump to the Frame number 96 (another two seconds later, in our animation). Still in side view, translate (G key) your object two units downward (keep the CTRL key pressed during this operation) and strike the ENTER key in order to validate the new location. Strike for the last time on the I key, but this time, choose only Loc, and pay attention to the changes in the IPO Curve Editor window.

IPO-frame-96

  • We will now comment it, before playing with it. On the 48th frame, we have a cube moded upward while in side view; this is a translation along the Z axis, so this the LocZ curve which will be effected in the IPO Curve Editor window. In this very same view, the cube has been rotated around its pivot poin; this is a rotation around the X axis, so this is the RotX curve which is effected.

::The IPO Curve Editor window::

It shows three parts. The main 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. The green cursor can be moved using the left mouse button, in order to show the state at a given moment (the current Frame automatically updates, as well as the 3D views).

  • Good to know: You can select a given curve, either by using the right mouse button directly on the curve, or by using the left mouse button on its name in the list on the right. A selected curve could be edited, using the TAB key. From then, you gain access to the key points that builds it, and you can modify them according to your wishes, using the now classic G key in order to translate the selected points.

On the right you can read all the parameters available for animation. They change according to the kind of parameters choosen, and this choice is made through the button menu IPO type, in the bar at the bottom of the window: you can get access to Object, Material, World, Texture, Vertex, Constraint, and Sequence parameters. Each of this option displays a different list of parameters available for animation.

Under the IPO Curve Editor window, you can find a menu bar. Most importantly, you will find there the IPO type button menu we already wrote about, and the Curve sub-menu, in which we will have a specific interest hereafter.

  • Interpolation mode: now that we have inserted a few animation keys, using the I key,we still have to define what lays between these points. For example, if we would like a discontinuous and jittery animation, we would coose the Constant option; for a smooth and continuous animation, we would choose Linear; and for a smooth and slightly dampened animation, we would choose the Bezier option.
  • Extend mode: this option lets you set what is the behavior of Blender when it reaches the very last animation key defined. By default, beyond the last key, the curve becomes horizontal, meaning that the animated parameter won't vary anymore as time passes; this is the Constant option. When choosing the Extrapolation option, the curve is then "extended" according to the last slope defined. The Cyclic option, on the other side, makes sure that the curve will repeat itself indefinitely according to the curve segments defined until now. And at last, Cyclic Extrapolation lets you both cycle indefinitely (as previously) and also extrapolate the increase in amplitud of the cycles, according to the animation keys previously defined.

::Final words about our animation::

In the IPO Curve Editor window, select the LocZ curve with the left mouse button. In the Curve > Interpolation mode menu, choose Bezier, and then, in Curve > Extend mode, choose Cyclic. The movements sequence defined with the animation keys will lead to a cyclic curve, with a smooth and continuous interpolation, slightly dampened.

LocZ

Now select the RotX curve with the left mouse button. In the Curve > Interpolation mode menu, choose Linear, and then, in Curve > Extend mode, choose Extrapolation. Doing thus, we make sure that the rotation speed of the cube around the X axis will stay constant (the curve show a single slope) up to infinite. We are done with our animation!

RotX

In the Scene menu (F10 key), in the Format tab, choose Jpeg, Quality: 90 and 24 Frs/sec. Finally, in the Anim tab, press the ANIM button in order to start the rendering of the animation, and PLAY in order to play it back within Blender once all the renderings are done.

simple-animation-part1-final