Domarius's animation tips
First you should check out the Motion Builder tutorial if you haven't already.
The overall process
Here's a summary of the steps;
- Record your reference footage. Or search for it, or act it out in the mirror.
- Set the distance the character moves
- Rough out the animation with key frames for the entire body at the main pose changes of the animation, like a slide show.
- Make the transitions less constant by inserting the extra key frame after the start key frame and before the stop key frame, for each pose. Still with the whole body selected, so your adding these key frames for each body part.
- Randomly shuffle those key frames around differently for each body part, then tweak it to look nice
- Shift the feet "landing" keyframes to some point earlier than when the mass of the body stops moving as a result of the foot landing down. This can sort of be part of the previous step.
- Apply the extra secondary movements caused by velocity, keeping balance, etc. pick them out carefully from the reference footage. You could do this on a separate layer.
- Can always add a "pose tweaks" layer if you come back and decide character is too hunched over in one part, or for the whole anim, etc.
If possible, film yourself or someone else going through a few variations of the animation you want (exaggerated, minimalistic, theatric...) and if it's a complex motion, you may want to capture each example from a few angles. If you can't film your own footage, act it out in front of a mirror, paying particular attention to the small sub movements.
Actually I really can't stress how good it is to have reference footage. Even if you just do a rough job of the overall movement, adding in the little sub movements that you can pick up from playing the footage over and over (arms swaying due to torso movement, shifts of the legs or arms to maintain balance, etc) the "believability" of the animation will increase ten fold. The viewer's brain will pick up on these "physics" cues and tell them the animation is "real".
Set the distance the character moves
If this is a "movement cycle" animation - All the animation tutorials I have read, have said to start animating with the stride pose - the point where the heel first makes contact with the ground. This is the base for the entire walk cycle. Depending on your needs, you might want to set the distance, or the stride length first. If the distance traveled is important, then begin by having the character float straight from their start position to their end position (by just setting a start and end keyframe for the origin), and then pose up a stride length on the first frame, to cover half that distance. If the distance is not important, then just start with the stride length with whatever looks right.
Don't forget to give the "origin" bone to the same key frames and positions as the character origin point. Motion builder's origin handle and Doom 3's origin bone are not the same thing. The origin bone is basically telling Doom 3 how far the character is actually moving.
Rough out key poses
If this is a movement cycle, then you should always start with two poses - the contact point (where the heel hits the ground) and the passing point (the mid point between each step where one leg is passing the other). Those two will form the base of the walk. Also you can repeat movements (such as arms swinging) over to the other limbs by copying and pasting key frames to other limbs and shifting them forward in time.
For other animations;
- To get the timing right, play the empty anim, and stop it where you think the peak of the first pose should happen
- Select all body parts and pose the character roughly the way they should be at that moment, and hit KEY to set a key frame for all body parts.
- Continue on for each major pose.
This way you can "sketch out" the general movement without dealing with a lot of key frames, since all the body part key frames will line up with each other and appear as one key frame, as long as all body parts are selected.
And later if you need to tweak the overall position for the entire duration of the animation, even after you've added a lot of detail key frames, you can always make a new layer and do it there. See the Motion Builder tutorial.
Whenever a foot or any body part makes contact with the ground or anything solid, you'll have a key frame where it makes contact, and then you'll have a keyframe where it leaves the surface. You'll notice by default, that even though both keyframes were made with the foot in the same place, the foot still moves weirdly between the two frames... as if sort of bouncing from the previous movement. To avoid this, you will want to kill any animation curves (in the Fcurves window in MotionBuilder) on the foot, after the point the foot hits the ground, and before it leaves the ground. This ensures it stops solid and stays perfectly still between the two frames.
Less consistant transitions
"Humanize" the overall movement with this technique - consider the transition from one pose to another, it takes 2 key frames; start, and then stop.
With these 2 keyframes
- Add a keyframe just after the start keyframe, and drag that forward to some point less than halfway between the start and stop.
- Add a key frame just before the stop keyframe, and drag that backward to some point more than halfway between the start and stop.
This makes for a slow movement at the start, and then a sharper transition into the final position, and then a small wobble as they hold the position. First big step to making it look less robotic.
Break up the perfect timings
Randomly adjust the timing of starts and ends of movements of each body part so that different movements are not starting and stopping at the same times at each other. Start random, and then use your artistic eye or reference footage to tweak it.
Contrary to what you might think, the part where the foot makes contact with the ground is the part of the animation with the least weight. It's the movement directly after this, (eg. downward movement of body) that sells the weight.
Whenever the center of mass changes and the character moves its feet to another position to maintain balance, the feet must reach their destination before their center of mass reaches the end of its movement. Because the feet is what causes the center of mass to slow and then stop moving.
So drag the feet "landing" key frames to occour before the rest of the body's frames they were previously aligned with.
Apply the more subtle movements, such as "secondary" movements - other indirect movements caused by the main action (eg. arms swinging gently after the torso has reached the peak of it's movement when leaning). Refer to the original footage for this. If you have used the mirror, go back and do the action again and this time look for the subtle movements.