At this point, you should all be familiar with how to pose your character. Rather than give exact values for rotations, translations, etc, we'll be looking mainly at poses and example animations. We'll also talk about important things to remember when animating particular actions. This tutorial will guide you through a process of making your character jump with both feet from one spot to another.
Comments on Squash and Stretch
The animation principle of "Squash and Stretch" are particularly important in a jump. You used squash and stretch in the walk, but in a more subtle way. In a jump, the body compresses and extends in a more extreme manner. The following is an outline of the key stages of a jump, and how this principle applies:
Recall the bouncing ball exercise. You used the same ideas in that animation.
Comments on Arcs
In the real world, almost all action moves in an arc. When creating animation, one should try to have motion follow curved paths rather than linear ones. It's seldom that a character or part of a character moves in a straight line. Nothing is ever perfectly straight. When a hand/arm reaches out to reach something, it tends to move in an arc.
Pose to Pose Animation
This tutorial will take a slightly different approach to blocking out your animation than the previous walk/run cycle tutorials did. We will be placing the character in full pose at our keyframes, rather than animating just the legs first, followed by the hips, torso, etc... The latter technique is called "layered" animation.
Starting Pose
We'll start by placing the character in a neutral, relaxed pose. This is a good point to start from, because it allows us to go through all the important stages that are required to complete a jump.
Here is an example of a neutral pose. Adam's torso was adjusted to reduce his straight posture. The arms were moved down to appear hanging to either side, and the torso and head were rotated slightly.
Squat before the jump
Here is Adam's first "squash". We'll set this pose at frame 30. Move Adam's ROOTCONS down and back a bit, rotating it positively about the X-axis. In our example, we've also adjusted the Bend Forward and Back attribute to give a nice arc to Adam's back.
You can also see in the front view that Adam's knees are bowed out a bit, the knee controls were moved outward to achieve this effect.
Position your character in a similar position and set keyframes on the controls.
30 frames may seem like a long time for your character to get to this position, but we're blocking out the animation right now, we want a rough sense of timing, but not necessarily exact. We will go over some tips on how to adjust the timing after we've finished blocking out the poses.
Take off extension
It can be very helpful to draw out the trajectory of your character's jump. The trajectory will determine much of your poses and animation. This extension in particular will vary depending on where and how high you want your character to jump. For example, if you want your character to jump a far distance, the body will make a smaller angle with the ground. Whereas if you want your character to jump higher, not farther, the body would remain more upright.
Below, we've drawn a curve in space to represent the trajectory we want Adam to follow.
Before you choose what frame to set your next pose in, think about how heavy you want your character to be. A heavier character would require more time to push it's weight up off it's feet, whereas a lighter character could get airborne pretty quickly. Adam is fairly slim and athletic, so we'll animate him as a lighter character.
We've chosen to set the next keyframe at frame 36. Adam's body is at it's fullest extension here. Here, his hands are leading the direction that he is taking off the ground. We've moved the arms, reversed the arc on the back, and moved the root forward and up a bit. Position your character properly and set keyframes.
Mid-Air
In our example, we've placed this pose at frame 44. In this pose Adam is tucking his legs, with his hands closer to his face, his body more in a "crouched" position, and his head up slightly as Adam looks to see where he's landing.
Pre-landing Anticipation
We decided that when jumping, Adam will be off of the ground for about 15 frames. Since Adam lifts off the ground at frame 36, he is about to touch down onto the ground at frame 51. Here, Adam is anticipating the ground. As he is about to land, his feet are going to be the first to touch the ground. Notice that he is landing heels first. If he were jumping straight up and down, he'd be more likely to land toes first instead. His arms, which had initially lead, now trail the rest of the body. We've moved the arms back, reduced the amount of arc on his body slightly, and rotated the root in the opposite direction.
Note that you can either rotate the root or the TORSOCONS in order to obtain the tilt in the body. We preferred to rotate the root instead since rotating the root gives for a smoother line in Adam's profile.
At this point, your animation should look something like this from the Side, Front, and Top.
The Landing
At frame 60, we set the landing pose. Here, Adam is given enough time to reach the ground and his pose is right after his body has absorbed the shock of hitting the ground. His legs are bent and his feet are flat on the ground. The hands are moved forward and down. His head is facing the ground a bit, his ROOTCONS is rotated forward, and his back is arched forward again.
From here, Adam stands up and the major key poses are done. We put the timing of this at frame 90 for now. Adam's weight is once again a factor here as well. How "heavily" he lands and how quickly he stands up will determine the frame position for his final stand. Does he stand up quickly or slowly? How quickly he stands up is also determined by how far his jump was or from what height he is landing from (the harder the jump, the longer the recovery time since his body is absorbing more energy and will be squashed lower to the ground).
Your animation should look something like this from the Side, Front, and Top.
Tweaks and things to keep in mind
Looking at the videos above, there are many things that obviously need to be tweaked with the jump. The poses above are the major compression/extension poses. There are quite a few in-between poses that need to be added.
Below is an example of how this could be done, and the resulting animation.
You can see that the hands still do not make a smooth arc. You can either manipulate tangents, or add a couple more keyframes until you get the desired swing. This is an example of the tweaked arm swing with a much smoother arc (NOTE: the arm swings were slowed down for clarity).
The timing during the first 30 frames was broken up to reduce the "smooth robotic" look. Adam gets close to the bottom of his squat faster, then slowly eases into his extreme squatting position.
Also, to break up the first 30 frames further, some anticipation was added to the arms. They now swing forward before swing back.
Tweaked version of the jump: Side, Front, and Top.
This jump is very similar to the regular jump. The major differences are outlined below.
For this exercise, create a cube that is a little past knee height for your character. Make sure that the top of the cube has enough room for your character to land on. When you're placing your cube, think about the trajectory you want your character to follow to get on top of the cube. We've drawn out trajectories below. Depending on your character's abilities, you will want to vary these.
By now, you should be quite familiar with posing your character, and which controls to use to get the character as you like. For the remainder of this tutorial, we will simply show example poses and example frame numbers to set the poses at. Also, many of the poses below are very similar to the regular jump poses.
Preparation
Here is the preparation pose. Adam will have to jump up to a good height to make it onto the box, so we have him squat pretty low. This is set at frame 27.
Takeoff
The takeoff is set at frame 37. You can see by Adam's positioning that he will be going up more than out, which is what we want.
Mid-Air
Here is the mid-air pose. We've set keyframes for this pose at frame 41.
Pre-Landing
This pose has been set at 47. Because Adam has to land on the box, which is closer to his high point in the air, his legs remain bent. This is different than the pre landing pose in the regular jump.
The Landing
This pose is set at fame 55. One thing to notice about this landing is that it does not take Adam as much distance to absorb the impact. As noted earlier, this is because the vertical drop from Adam's high point to his current position was not as great a distance as in the regular jump. Less distance means less time to accelerate, and thus less force.
Recovery
We've set this pose at frame 76. The timing between the landing and the recovery is important as usual. In this case, it shouldn't take Adam as long to recover, since the amount of force driving him into the landing wasn't as strong.
We've left some time between the last pose we used in the portion where Adam jumped onto the box, and the start of this portion. We do this in case we want to easily add to the previous animation, or to the beginning of this animation when we're through, it's basically a "cushion". This section starts at frame 90.
Preparation
We set this pose at frame 120. This gives us ample time to add some details, such as Adam looking down to spot his landing, and to give him some time to look like he's preparing to jump down. This makes Adam seem a bit pensive and careful, as he prepares to jump down.
"Takeoff"
Adam does not need (or want) to jump high since he already has a larger drop to deal with. Notice that the angle of Adam's body looks as though is is falling forward. This is good, since it makes it so that Adam's drop is as small as possible. You could have your character really jump off the box if you choose, just keep in mind that during the landing and recovery, your character will have more force to overcome than we will show in our example. This pose is at frame 134.
Mid-Air
Frame 138. Adam is already descending rather than at the height of his jump. The reasons are as noted above. Notice also that Adam's arms are dragging behind him as he falls.
Pre-Landing
Frame 141. Just before Adam lands. The arms continue to drag and the legs are bent to prepare for impact. There is very little time between the last pose and this one since Adam has had some distance to accelerate.
The Landing
Frame 152. Adam's squat is pretty low, since he has had a larger drop to absorb.
Recovery
Frame 190. We've given Adam plenty of time to recover from his "large" fall. Depending on the height of your box, this timing will vary.
Tweaks and things to keep in mind.
Things that need to be tweaked are fairly similar to the standing jump. As before, timing and tweaking the key frames, among other things, are important to keep Adam from looking too robotic. Be sure to go through your checklist of things to pay attention to to get a better animation.
In our final version of the box jump, we've removed the arm constraints in order to use forward kinematics on the shoulders and elbows. This is a matter of preference and what you feel would make things easier for you as you animate.
Here is a version of the above animation complete with some tweaks and details added. Side, Front (with the box-semi-transparent), Top, and Perspective
Try varying your trajectory. Animate jumps of varying distance and height. Try animating a trajectory that isn't humanly possible. What problems arise?
Jason Ilano, 09/2000
