VARKON Version 1.15 1997-10-16

### Coordinate systems

There are two ways to create a coordinate system in VARKON. You can use....
csys_1p(#1,name,p1,vx,vy,vz);
which creates a coordinate system with origin in p1 rotated in order vx degrees around the X-axis then vy degrees around the Y-axis and finally vz degrees around the Z-axis. The other way is...
csys_3p(#1,name,p1,p2,p3);
where p1 is the origin, p2 a position on the X-axis and p3 a position in the XY-plane indicating the direction of the positive Y-axis. In both cases the coordinate system should be given an appropriate name indicating its purpose.
Coordinate systems created like this are LOCAL systems. A LOCAL system is activated using...
mode_local(id);
where id is the identity of the system to activate. When a LOCAL system is activated all coordinates and angles used to create new geometry is treated as relative to the LOCAL system. Geometric operations requiring a 2D plane also use the XY-plane of the LOCAL system when this is active. There is no limit to the number of systems that can be created and any system can be activated in any order as often as needed.
Every module has a default coordinate system created and activated automatically when it starts its execution. This system is called the module's GLOBAL system and is always active until a LOCAL system is activated with mode_local. To activate the GLOBAL system again use....
mode_global();
There is also a coordinate system in VARKON called BASIC. The BASIC system is the superior main coordinate system that all other systems are related to and also the system to which all geometry is transformed when saved in the GM database. GLOBAL and BASIC may seem the same but GLOBAL systems can change when one module calls another and therefore there is also a....
mode_basic();
in VARKON for those modules who want to be absolutely sure that something is done relative to the BASIC system.

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