The key to animating a walk cycle is to understand how the legs PUSH THE MASS of the body forward, and how the feet connect with the ground.
When we walk we move our MASS in four stages:
This illustration shows one step - remember to animate the second leg!
Key frames for a walk cycle
To animate a walking cycle, you need three key frames (1, 2 and 3 in the list above), and one breakdown position ( 4 ) the passing position.
Most walking cycles work best at 9 frames per step = 18 frame cycle for both feet.
The animation presented here below is slower - this is a 24 frames walkcycle (for both legs) at 24 fps:
The most important question of all is:
Where is the MASS?
The mass needs to be above the feet and slightly forward.
The more forward it leans, the faster your character should walk.
Look out for a common mistake - check each frame and make sure the body didn't get left behind... (maybe it doesn't want to go? :-)
The best way to animate is to move the big mass first, and then the rest of the body.
Whenever you get confused, ask yourself this:
Which leg supports the weight in the frame I'm animating now?
The answer will solve 90% of all your problems.
This leads us to the second most important thing:
Keep your feet on the ground!
Make sure the feet keep good contact with the ground -
Don't let them slip.
Here is the logic of it:
If a foot now supports the body weight, then IT CANNOT MOVE!
SO when you animate - determine which foot supports the weight,
and FREEZE it.
Disable the tweens.
Delete foot keyframes until you reach a frame when this foot must move again - and the other foot takes on the weight.
The body mass goes up and down
As we walk, our legs push our bodies upward as well as forward, and we rise and fall with each step.
The lowest part is the bounce, key frame #2, when the front leg receives the weight and bends under it.
The highest part is the passing position, where we stand on one straight leg. (Green Passing Position break-down frame)
The above formula is just that:
You need to modify it for your characters.
Here are some things to consider:
If you're creating a walk cycle animation for a game, you might want it to happen "on the spot".
In my experience it's best to animate a normal advancing double step first, and only when you're happy with it, "squeeze" the key frames in.
Mark the center of gravity with a guide line and cut and paste the character in each frame to this center.
The arms swing back and forth opposite to the legs.
When the right foot is forward - the right arm goes backwards.
Passing position for the arms happens together with the legs passing position.
Now all you have to do is walk the walk :-)