Window Grafics2
When you have chosen dato ta and latitude bg the angle of sun against horizon is shown obviously only during daytime. The slide td gives the time by a special table calculation. If it is animated the sun moves in the lightblue field of daylight and the point Bg in 3D-Grafics. If you want to observe that you should shut down all animations in the "Grafics"-window.
The line of function is no projection of the suns way to any plane because that would give a singularity if sun is running through zenith.