Autodesk Maya provides a wealth of tools for animating scenes in 3D.
However, before tackling complex animations with many moving parts,
it’s best to learn some basic animation techniques first.
In this tutorial series, we’ll show you how to give life to this assembly line with keyframe animation,
driven key animation, and animated textures.
Let’s start with keyframe animation.
Open the scene "assembly_line_part1_start.mb".
As with traditional hand-drawn animation, Maya creates the illusion of movement
by producing a series of still-frames in sequence where each image is subtly different from the last.
Each of these images corresponds to a single frame in the Time Slider,
located at the bottom of the Maya interface.
The Time Slider shows you the number of frames in the scene,
as well as highlighting the current frame displayed in the workspace.
A scene can have as many frames as you want. This scene is comprised of 480 total frames.
Because the Time Slider is measured in still frames and not seconds,
the actual length of your animation is determined by the “Playback Speed” setting in Maya.
Click the Animation Preferences button below the Time Slider to open the Time Slider properties.
Make sure that Playback Speed is set to Real-time [24fps].
This is a typical standard in film and animation,
and indicates that 24 frames will compose 1 second of animation,
and that Maya can skip over frames if necessary to maintain that speed.
That works out to a 20 second animation.
Let’s start animating our minion’s tentacles.
In order to move the minion_bottom_AST across the conveyor belt,
we’re going to use a process called keyframing.
A keyframe is a snapshot of an object’s attribute values on a certain frame.
By setting keyframes at different points in time,
Maya automatically calculates the movement in between those frames.
Click the timeline on frame 36 to set it as the current frame.
Now using the Move Tool or the Channel Box,
translate the minion_bottom_AST to -786 in the Z-axis.
In the Channel Box, right-click the Translate Z attribute and select “Key Selected”.
Notice that the attribute turns red and a red line appears on the current frame in the Time Slider.
Now click the timeline on frame 325.
Move the mesh along the Z-axis to 333 and set another keyframe.
Now click the rewind button to go back to the beginning,
and then click the play button.
The tentacles start moving across the conveyor belt from frame 36 to 325.
If you want more minute control over the playback,
you can scrub through the animation by dragging the mouse over the Time Slider.
With your first animation finished,
let’s go back further and animate the tentacles falling down this chute.
Scrub to frame 0.
Then use the Move and Rotate tools to position the tentacles at the top of the chute.
This time, we’ll need to keyframe both the translation and rotation since both have changed.
Let’s use the Animate > Set Key command, or the shortcut key “S”.
This is a quick way to key all the attributes in the Channel Box at once.
Scrub the Time Slider.
There’s a problem. Although the tentacles move correctly in the Z-Axis,
they remain at the initial height and rotation of the chute.
This is because at frame 36, we only keyed the Translate Z value.
Let’s reset the Translate Y and Rotate X values back to 0
and key all the attributes with the “S” key again.
Scrub through the animation again
and you can see that the tentacles correctly descend to the conveyor belt.
That said, they don’t adhere very closely to the chute.
This is because with just two keyframes for reference,
Maya only calculates a linear path from the first position to the last.
To smooth out the animation, we’ll add some interim keyframes.
Let’s keep track of the changes in attribute values by using Maya’s Auto Key feature.
Auto Key will automatically generate keys
whenever you change the value of an attribute that was keyed in a previous frame.
Go to frame 10 and re-adjust the tentacles so they sit on the chute.
This is easiest if you set the Move Tool to Object space.
With Auto Key enabled, Maya automatically sets keyframes.
Repeat this for frame 20 and 30.
The more keyframes you set, the more precise your control over your animation becomes.
Play the animation again and you’ll see the tentacles adhere much more closely to the chute.
If you look closely you’ll notice that the speed of the animation tapers at the beginning and end.
At the top of the chute the minion_bottom_AST begins falling slowly,
then speeds up towards the middle of the chute and across the conveyor belt,
before slowing down on the transport.
Maya creates these slow-in, slow-out tapers in animation by default.
This makes sense for the chute, since the tentacles start falling from a dead stop.
However, on a conveyor belt that moves at a fixed rate,
the minion_bottom_AST should actually move at a constant speed.
Right now, they start slowing down while still on the conveyor.
We can adjust this using the Graph Editor.
The Graph Editor displays your animation keys in a grid,
where frames are listed horizontally and attribute values vertically.
Each key connects to the next via animation curves, which represent their interpolation.
Thus by adjusting these curves, you can change the speed and timing of your animation.
Select the minion_bottom_AST and open the Graph Editor
from the list of Animation Editors in the Window menu.
You can navigate this editor using the same track and dolly hotkeys you use in the workspace.
Here we see the graph of the tentacles’ movement.
Focusing specifically on the Translate Z value,
notice that the curve tapers at frames 0 and 325.
We can leave frame 0 alone, since we want the tentacles to speed up as they go down the slide.
Let’s even out the speed at the end of the conveyor belt.
Select the keyframe at frame 325 and then the left tangent handle, also known as the ‘in tangent’.
Select Tangents > Linear to straighten out the tangent.
Let’s also straighten out the tangent at frame 36 when the tentacles first board the conveyor belt.
Now the animation curve is a straight line, indicating a constant speed over time,
which you can confirm by playing the scene.
However, we actually do want the tentacles to slow down gradually
once they’re off the conveyor belt.
Scrub the Time Slider to frame 300.
Set a keyframe on the Translate Z attribute.
Notice that a new point corresponding to that frame is added in the Graph Editor.
Now select the in tangent at frame 325 as before and select Tangents > Auto.
You once again have a taper at the end of the animation,
but it only stretches as far as the new keyframe you inserted at frame 300.
You can manually tweak the tangent further by using the Move Tool and dragging it.
Note that by default the in and out tangents are joined and thus move together.
To move only one tangent, use the "Break Tangents" command to separate them.
For now though, we’ll leave them as is.
Thus far we’ve animated our minion’s tentacles down the chute and across the conveyor belt.
In the next movie, we’ll finish assembling him by delving further into keyframe animation.