
RogCAD home back to RogCAD history Original notes and derivations for RogCAD, April 1993 preCAD planning sketch The first nine images below are of the non generalized derivation (predefined perspective point and focal point) of the floating image plane and projection of a structure. The second batch of nine images is of the generalized derivation (variable perspective point and focal point) which is much more complicated. Vector crossproduct is used to create a floating image plane with a normal vector that passes through the origin of the xyz axes. Points on the structure are projected onto the floating image plane. Vector dotproduct is used to test from which side of the zaxis each projected point stems. After the initial vector considerations, it's just algebra. But the magic of algebra fascinates me, especially when it goes on for many pages and it actually works. If you are using a laptop or desktop computer, you might want to magnify this page to 150 percent. Microsoft Edge browser users should click on the three dots ... at the upper righthand corner, then use the "zoom" feature. Vertical three dots for Chrome browser users. Those derivations produced the original program code for a specific perspective point and focal point: The program printout on the dotmatrix printer: The first RogCAD output. The points had to be plotted on paper: Derivation of floating image plane and projection of structure, generalized, next nine images: The generalized calculator kernel printout on the dotmatrix printer: back to RogCAD history RogCAD code  complete RogCAD home 
