A SIMPLE VIEWING GEOMETRY

Publisher Summary This chapter describes a simple viewing geometry. Sometimes, it is handy to be able to set up a simple viewing geometry; for example, packages without matrix libraries, quick preview hacks, and simple ray tracers all can benefit from a simple viewing construction. This chapter describes one such simple viewing geometry. The input is a viewpoint E , a gaze direction and distance G , an up vector U , and viewing half-angles θ; and φ. The output is a screen midpoint M and two vectors, H and V , which are used to sweep the screen. The chapter illustrates the setup for this viewing geometry. If the origin is assumed in the lower left, then any point S on the screen may be specified by ( sx , sy ), both numbers between 0 and 1.