Programmable graphics

Graphics commands and functions

In RR there are two graphics commands to control the line graphic element: setting the points, and the location.
There are two other functions that can be useful, setting the angle and the length. (The existing angle property in LC relates to the arc length which is not applicable to a line. There is a geometrical angle defined for images and regular polygons, but none for the lowly line.)

I have also added a command to join two lines together, placing the tail of the second on the tip of the first, all the while preserving the angles. Another useful function is the "perpProjPt", the point of intersection when a perpendicular is dropped from a point to a line. This is particularly useful in collision detection and dragging a object along a defined path.

There is also a function that returns the intersection points of two circles. I have recently considered putting down sod, which involves finding the area of an irregular polygon so that I may place a order. Surprisingly this involved intersecting circles.

There is also some applications doing for ellipses what we usually reserve for circles.

I have always restricted myself to objects moving relative to the window. But I find that it is not difficult to to do a kind of programmed motion within motion, specifically motion of objects moving within a moving group. This opens up an interesting new possibilities--beyond those abailable to concurrent "move" commands.

After 40 years of teaching, I have learned one immutable fact: an example is worth a thousand pictures--and we all know how many words a picture is worth. (My God, that's a million.The verbosity is staggering.) It is not enough to know the graphic language, but more importanly, recognize how to use it. Many of the examples are frivolous, but one man's frivolity is another's reality. a description of your stack here>