OpenGL SuperBible读书笔记(Introduction to 3D Graphics and OpenGL)

学习OpenGL的一大难点就是OpenGL里的一些基本概念，需要一定的基础积累

关于3D real time 的机制：将3D场景投射到2D的屏幕上，其原理就同真实场景投射到视网膜上的原理是一致的。

Viewports: Mapping Drawing Coordinates to Window Coordinates

Rarely will your clipping area width and height exactly match the width and height of the
window in pixels. The coordinate system must therefore be mapped from logical Cartesian
coordinates to physical screen pixel coordinates. This mapping is specified by a setting
known as the viewport. The viewport is the region within the window’s client area that is
used for drawing the clipping area. The viewport simply maps the clipping area to a region
of the window. Usually, the viewport is defined as the entire window, but this is not
strictly necessary; for instance, you might want to draw only in the lower half of the
window.

关于Perspective

2D + Perspective = 3D