Each different output display that uses the Simple projection type renders the scene from the current camera's position using a frustum that is defined by a rectangle with a defined size and placement in the 3D VR space. Each of these rectangles is defined by a screen configuration. Usually, each of these projection screens has the same dimensions in space as the physical screen that you'll use to render it.

The pivot point of a screen is always in its exact midpoint.

这段描述的是：针对每一路不同的显示输出来说，（这里仅涉及采用简单投影关系的输出），它们输出或显示的内容是对场景的渲染结果，这个渲染的（在场景里的）范围，是用当前相机的位置和一个视锥体来描述的，而这个视锥体是由3D空间中一个有确定尺寸和位置的矩形来定义的。每一个这样的矩形，都由一个Screen配置（或说Screen Component）来定义。通常，每个这样的投影Screen（组件）都与用来显示这个（Screen组件定义的渲染范围的）渲染结果的物理屏幕拥有相同的尺寸。