Real-Time 3D Graphics with WebGL 2 - Second Edition

Projection Transform

The next operation is called the projection transform. This operation determines how much of the view space will be rendered and how it will be mapped onto the computer screen. This region is known as the frustum and it is defined by six planes (near, far, top, bottom, right, and left planes), as shown in the following diagram:

These six planes are encoded in the Projection matrix. Any vertices lying outside the frustum after applying the transformation are clipped out and discarded from further processing. Therefore, the frustum defines clipping coordinates, and the Projection matrix that encodes the frustum produces ...