VARKON Version 1.15 1997-10-16

### Points and lines

A point is a geometric entity occupying a specific position in space. Points are created using one of the following methods....
poi_proj(id,p1);
poi_free(id,p1);
The proj version indicates that position p1 is projected onto the XY-plane of the active coordinate system before the point is created. The free version creates a point anywhere in 3D space.
There is also a proj and a free version of the line entity....
lin_proj(id,p1,p2);
lin_free(id,p1,p2);
A line entity is always straight and limited. There are no infinite or semi infinite line entities in VARKON. (If you need something with direction and infinite length you can use the VECTOR datatype). Other ways to create a line are....
lin_ang(id,p1,angle,length); ! From p1 with angle and length
lin_offs(id,other_line,distance); ! Offset to other line at distance
lin_perp(id,p1,other_line,length); ! From p1 perpendicular to other line
lin_tan1(id,p1,other_entity,alternative); ! From p1 tangent to arc or curve
lin_tan2(id,other_entity_1,other_entity_2,alternative); ! Tangent to two arcs
The parameter named alternative in lin_tan1 and lin_tan2 is used to distinguish between different possible solutions. In lin_tan1 for example it could very well be the case that a straight line from p1 can find more than one point of tangency on a curve or arc. For a closed circular arc there is always two points of tangency and for a curve that oscillates there could be more than two.
VARKON enumerates solutions (tangency points) in the order they appear when traveling along the curved entity in its right sense of direction and the parameter named alternative above is then used to select the right solution. A 1 for the first, 2 for the second and so on.
A line can be converted to a curve using cur_comp.

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