动画的12条基本原理
1 Timing 节奏
It may seem kind of silly to even have something as basic as timing on the list. Obviously timing is the essence of animation. The speed at which something moves gives a sense of what the object is and why it is moving. Something like an eye blink can be fast or slow. If it's fast, a character will seem alert and awake. If it's slow the character may seem tired and lethargic.
有些人会觉得把timing（节奏）放在法则列表里似乎很愚蠢，因为这个对动画制作来说实在是太基本了。显而易见，“节奏”是动画的基本要素。物体运动的速度说明了物体物理本质，和运动的成因。仅仅是“眨眼”的动作就可或快或慢。如果眨的快，角色看上去就处在“警觉或者醒着”的状态，如果眨得慢，角色就会显得比较慵懒，疲惫，昏昏欲睡。
John Lasseter gave a good example in his famous Siggraph paper using a character with a head that turns left and right. Essentially, he gives different durations for the exact same head turn motions, and shows how it can be 'read' differently based merely on the timing. If the head turns back and forth really slow, it may seem as if the character is stretching his neck. A bit faster it can be seen as saying "no". Really fast, and the character is reacting to getting hit by a baseball bat.
John Lasseter在他的那篇著名的Siggraph论文里使用了一个关于头部从左向右的转动的范例。虽然是同一个转头的动作，但他按照不同的时间节奏做出来，却表现出不同的意思，而本质上他仅仅是改动了运动的timing“节奏”而已。如果头从后往前转的很慢的话，角色看上去只是在活动颈部而已。加快一点速度，看上去就象是在说：NO! 再快点，角色看上去就很象被物体砸到头部一样。
Having a good sense of timing is critical for good animation. Cartoony motion is usually characterized as fast snappy timing from one pose to another. Realistic tends to have more to do about going between the poses. But both require careful attention to the timing of every action.
对于好的动画来讲，好的“节奏”感非常重要，非常基本。动作的卡通风格一般要求物体从一个pose(姿势)到另外一个pose的变换很灵活简洁。写实风格的则要求在pose之间细节上要有变化。但是无论哪种风格，都要注意每一个动作的timing节奏问题。
I think it was Chuck Jones who said "The difference between the right timing and the almost right timing, is the difference between lightning and a lightning bug."
记得Chuck Jones曾经说过：“好的timing节奏和差强人意的timing节奏之间的差别就有如“光”和发光的萤火虫之间本质的差别”。
2 Ease In and Out (or Slow In and Out) 渐进和渐出（或慢进慢出）
Ease in and out has to do with gradually causing an object to accelerate, or come to rest, from a pose. An object or limb may slow down at it approaches a pose (Ease In) or gradually start to move from rest (Ease Out).
渐进和渐出的规律通常是运用在物体pose的加速或减速变化过程中。一个当物体接近某个POSE时，通常是减速变化的（称之为渐进或慢进）；相反地当它从一个POSE开始向另外一个POSE变化时，应该是加速的（称之为渐出或慢出）。
For example, a bouncing ball tends to have a lot of ease in and out when at the top of its bounce. As it goes up, gravity affects it and slows down (Ease In), then it starts its downward motion more and more rapidly (Ease Out), until it hits the ground.
比方说，一个弹跳的小球凡是在它达到顶点的时候都会有渐进和渐出。当它起跳时，受重力影响速度应该越来越小(即渐进)。当它向下运动的时候应该逐渐的加速(渐出)，直到它触地为止。
It's important to note that "gradually" here doesn't have to mean slow. It just means the object isn't moving 100% and then in one frame coming to a complete stop. For snappy cartoon motion, you may have ease in and out over only a couple of frames. But even 3 frames of ease in and out may help a limb from looking too stiff or mechanical.
需要注意的是这里“通常“并不意味着速度慢。真正的意思是物体运动不必本来是全速前进但只是用一帧就嘎然而止，这是不行的。卡通类型的动作里你只要2帧来做这个渐变过程就可以，但如果是用3帧来做，看上去就会比机械的僵硬的动作好很多。
As applied to character animation, you usually use ease in and out for most movemnts. Even if the character is just turning their head, you will probably want a few frames to soften up the start or end of the motion.
对于角色动画，你总是要在运动中加入渐进或渐出的处理。即便角色只是旋转了一下头部，你也可能需要在动作的起始和结束的地方加一些帧使之更平滑些。
3 Arcs 运动弧线
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 is very seldom that a character or part of a character moves in a straight line. Even gross body movements when you walk somewhere tend not be perfectly straight. When a hand/arm reaches out to reach something, it tends to move in an arc.
在现实生活中，所有的运动都是有弧线的。当做动画的时候你应该让动作沿着曲线运动而不是线性的直线。很少有角色或者角色身上某个部位的运动是直来直去的。甚至当你整个身体在行走过程中也不是呈一条直线运动的。当手或者胳膊伸出去触摸物体时，都是按照曲线来运动的。
Sticking with the head example, the head rotates in an arc like fashion. That is if a characters head rotates from left to right, at the halfway point, it should actually be dipped or raised slighly depends on where it is looking. This stops the rotation from being perfect linear or mechanical looking.
还是拿头部运动来做范例，头部象扇子一样呈弧线旋转运动。也就是当头部从左象右转动时，在中间位置头部应该根据他视线看的方向加一点低头或者抬头的动作，而不是纯线性的旋转或者机械式的动作。
