class TGLCameraMarkupStyle

TGLCamera

Abstract base camera class - concrete classes for orthographic and
persepctive cameras derive from it. This class maintains values for
the current:
i)   Viewport
ii)  Projection, modelview and clip matricies - extracted from GL
iii) The 6 frustum planes
iv)  Expanded frustum interest box

It provides methods for various projection, overlap and intersection
tests for viewport and world locations, against the true frustum and
 expanded interest box, and for extracting eye position and direction.

It also defines the pure virtual manipulation interface methods the
concrete ortho and prespective classes must implement.