perspective()

T更小，变化的幅度决定于属性值的变化大小

语法

```perspective(l)
```

参数

l

Cartesian coordinates on ℝ2 Homogeneous coordinates on ℝℙ2 Cartesian coordinates on ℝ3 Homogeneous coordinates on ℝℙ3

A perspective is not a linear transform in ℝ3 and cannot be represented using a matrix in the Cartesian coordinates system. $\left(\begin{array}{ccc}10& 0& 0\\ 01& 0& 0\\ 0& 0& 1& 0\\ 0& 0& -1/d& 1\end{array}\right)$

TBD