Introduction

In this tutorial you will learn how to animate a quadrupedal cycle, in particular a horse as they are one of the most common animals to be animated. A horse can move in several different ways from walking, ambling or trotting but we're going to look at the gallop; it's fastest form of movement, allowing us to make  full use of it's muscles and limbs. This tutorial is intended for beginners with a basic knowledge of Maya and the animation principles.

Getting Started

The first thing is to find some real horse galloping reference and Eadweard Muybridge is a good place to start. Below is a page from his book Animals in Motion and it'll provide the key poses for our animation.

Now you'll need to find a rig. I found a pretty decent free rig which I'll be using in this tutorial, but of course you can use your own.

This is Rhett the Clydesdale

Modeled by Tim Mayo

Rigged by Christopher Carson

Downloaded at Creative Crash 

Setting up the Scene

With Muybridge's images for reference and a downloaded rig, we can begin. Firstly open up Maya and create a new project file and put the horse rig into the scene folder. Now open the scene and bring out the Preferences window inthe bottom right corner.

Under Settings set the Time to "PAL (25fps)". And under Animation, select "Flat" for both in and out tangents.  This will give a nice ease-in and ease-out. In the Timeslider section set the Playback to "Play every frame" and "Real-time (25fps)" and click save.

Now turn on Autokey by clicking the key icon next to preferences inthe bottom right hand corner. It should now be red. This tool will make our lives easier, as Maya will now automatically keyframe any changes.

Starting to Animate

In our Muybridge reference there are 16 poses, so set the whole animation to 16 frames.

In the side view, key frame the first pose concentrating on just the legs by translating and rotating the ankle controls and rotating the hoof controls. You don't need to be perfect but just to get a basic idea of the poses, as we'll be tweaking parts as we go along.

The first and last frames need to be the same to create a cycle, so select all the controls on frame 1, and with the middle mouse button click on frame 16 and press "S". This allows us to keep the pose the same whilst moving along the timeslider.

Blocking out the Poses

Now we just need to continue posing out each frame according to the Muybridge image, and remember to concentrate on just the legs.

Your key frames should look something like this, and notice that in some of the frames the legs aren't straight enough or need to be stretched out further but this can be altered later on.

Shoulders

After key-framing the legs we work our way up to the shoulders. They need to be furthest out when the legs are extended out to their maximum. Let's start with the right shoulder. 

Start at frame 1 and select the shoulder control. Rotate X forward slightly to about 15units and Translate Z back to around -0.5. Notice the leg is slightly bent now, but we want it to be completely straight, so select the ankle control again and move it back until it's fully straight but still touching the ground.

Your first frame should look something like this. When we rotate the shoulders it allows the legs to stretch out much further giving more extreme poses. With the first frame done, shift select the shoulder and ankle control and middle mouse click on the last frame and press "S" because again, the first and last frames must be the exact same. So any changes to the first frame, you need to remember to do the same for the last. 

With the first shoulder key frame done we need to find the next frame where the shoulders would be furthest rotated and translated, which I think would be frame 8 as this is where the leg is highest and just about to kick out and down. So we'll do the opposite of what we did for frame 1, by rotating X back and translating Z forward a little.

Now we need to repeat the same process for the left shoulder, first scrubbing through the frames to see where the leg is furthest forward and back.

So for the left shoulder, at frame 5 the leg reaches it's maximum height so we can Rotate X back and Translate Z forward, only slightly like for the right shoulder as we want the shoulders to look natural.

And at frame 13, where the leg is stretching back do the opposite as before, of Rotating X forward and Translating Z back. As this gallop is an asymmetric cycle, the leg positions won't be the exact same on the right to the left so there's no need to worry about having the same units for both legs. Making each leg move slightly differently to each other will make it look less mechanical and give a much more realistic feel to the run.

Hind Legs

We also need to do the same with the back legs, but they can be much more exaggerated than the front as they're more flexible and use more power to push off the ground. Again we'll need to scrub through the frames and judge where the legs is furthest forward, which I think is frame 6 for the right leg. Start by selecting the "rt_rearLeg_CTRL" and Rotate X back to about -30, and Translate Z forward slightly.

And frame 12 where the legs are kicking out, Rotate X forward so the leg is higher and Translate Z back so they are further out. 

And now we begin the same process for the left back leg. For the left side, at Frame 2 where the leg curls up and forward before kicking down, select "lf_rearLeg_CTRL" and Rotate X back and Translate Z forward.

The left back leg kicks out again at Frame 11 just before the right leg falls back down, so Rotate X forward and Translate Z back, again no need to worry about exact units.