真實(shí)的運(yùn)動(dòng)（Authentic motion）
In the world of material design, motion describes spatial relationships, functionality, and intention with beauty and fluidity.
在material design的世界，動(dòng)效美觀及流暢地描述了對(duì)象的空間關(guān)系，功能及意圖。
體積和重量（Mass and weight）
在物理世界，物體的運(yùn)動(dòng)需要有動(dòng)力，運(yùn)動(dòng)也不會(huì)瞬間發(fā)生。material design的運(yùn)動(dòng)也有類似的表現(xiàn)，同時(shí)也不失優(yōu)雅、簡(jiǎn)樸與美觀。
1.自然的加速和減速（Natural acceleration and deceleration）：加速和減速的變化是平滑的，而且加速和減速的變化是不對(duì)稱的；避免線性運(yùn)動(dòng)，突然的速度變化是機(jī)械的，不自然的。
2.進(jìn)入和離開（Entrances and exits）：
An object’s change in speed as it enters or exits the frame suggests the distance it is traveling.
一個(gè)對(duì)象進(jìn)入和離開框架時(shí)的速度變化表達(dá)了它運(yùn)動(dòng)的距離。
物體從外部減速進(jìn)入而逐漸加速離開更為自然真實(shí)，而快速的進(jìn)入和緩慢的離開會(huì)過于吸引用戶的注意，分散了用戶的注意力。
3.關(guān)于“ease”（About “ease” term）：
The terms “ease in” and “ease out” are used in both traditional animation and UX animation. However, depending on the context, these terms have opposing meanings.
“ease in”和“ease out”的概念在傳統(tǒng)的動(dòng)畫和在UX動(dòng)畫中均有被使用，但是確實(shí)兩種相反的含義。
在傳統(tǒng)動(dòng)畫中，描述的是對(duì)象進(jìn)出關(guān)鍵幀時(shí)的時(shí)間曲線。而在UX動(dòng)畫中，描述的是對(duì)象進(jìn)出轉(zhuǎn)場(chǎng)時(shí)的時(shí)間曲線。
4.做出調(diào)整（Making adjustment）：
Not all objects move the same way. Lighter or smaller objects may move faster because they require less force, and larger or heavier objects may need more time to speed up.
不是所有對(duì)象都有相同的運(yùn)動(dòng)方式。更輕或更小的對(duì)象因?yàn)樾枰〉膭?dòng)力而運(yùn)動(dòng)得更快，而更大或更重的對(duì)象需要更多時(shí)間去提速。
Find a curve that fits that character of motion you are describing.
找出符合你想表達(dá)的運(yùn)動(dòng)特征的曲線。
