VARKON Version 1.15 1997-10-16

### Composite curves and trimming

Straight lines, circular arcs, cubic rational curves, UV-curves, offset curves and composite curves can be combined in any order to create new composite curves using...
cur_comp(#1,cur_id_1,cur_id_2,.......cur_id_n);
VARKON checks that C0 continuity is preserved but lets you define a kink if that's what you want to. Composite curves act exactly as all other curves in VARKON. You can create an offset to a composite, you can use a composite for intersects and you can even define a surface using a composite.
If you need to reverse the sense of direction for a curve or just need to make it shorter then the following method can be used.....
cur_trim(#1,cur_id,parval_1,parval_2);
cur_trim changes the parametrisation of a curve by making the position corresponding to parval_1 its new start and the position corresponding to parval_2 its new end. By simply supplying the old end as the new start and the old start as the new end a new curve is created with opposite sense of direction. By supplying values elsewhere the curve is cut and reparametrised on the new interval. This is the same as trimming. Splitting is a similar operation (opposite to cur_comp) where cur_trim is used to divide a curve in two or more separate pieces each piece being a new curve of its own.
cur_trim can also be used for extrapolation of the first or last segment of a curve. Extrapolation is made by first creating a new segment using the same coefficients as the old segment but the new (larger) interval for curve parameter and then reparametrise the new (longer) segment to the standard interval 0 -> 1.

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