ParametricGeometry 允许你用数学公式来定义形状。这里的 klein 函数生成了一个著名的数学模型——克莱因瓶。它是一个没有“内”和“外”之分的奇怪瓶子。对于初学者，你只需要知道：只要你能写出 x, y, z 的方程，Three.js 就能帮你画出模型。
Sketched out concepts, using Excalidraw[2]
，这一点在WPS官方版本下载中也有详细论述
Petrochemicals – of which plastics are the dominant output – now account for roughly 75% of net global oil-demand growth, and are projected to become the largest driver of future oil demand. Plastic production has already doubled in the past two decades. Major oil companies are responding accordingly. Recent consolidation – including a $60bn merger creating one of the world’s largest plastics producers – reflects a deliberate pivot toward petrochemical assets as a long-term demand anchor.
The paid plans are a bit pricey because they include many tools for content optimization.