VARKON Version 1.15 1997-10-24

sur_cyl - Geometric procedure

Creates a surface


Description

Creates a cylindrical surface by translating (sweeping) a profile (line, arc or curve) a specified distance perpendicular to the plane of the profile. If the profile is not a plane curve or if the profile is a line VARKON automatically creates a "best possible" plane. If this is not satisfactory an arbitrary sweep direction may be specified.

Syntax

sur_cyl(id, profile, distance, reverse, dir:attributes);

REF	id;
REF	profile;
FLOAT	distance;
INT	reverse;
VECTOR	dir;

Principal parameters

id	- Local identity
profile	- Identity of arc or curve
distance	- Length of cylinder (surface V-direction). May be negative.

Optional parameters

reverse	- Controls the parametric directions of the resulting surface
	1 = No reversal of input (default)
	-1 = The profile curve (U-direction) is reversed
	2 = The sweep (V-direction) is reversed
	3 = Both are reversed
dir	- Sweeping direction if not perpendicular to the plane of the curve. Default = (0,0,0)

Attributes

PEN	- Pen or colour number
LEVEL	- Level number
BLANK	- Visible(0) or invisible(1)
SDASHL	- Dashlength

Example

sur_cyl(#2, #1, 50);

Creates a surface by sweeping #1 50 units in the same direction as the normal of the plane of #1.

sur_cyl(#2, #1, 50, -1);

Geometrically the same surface but with parametrisation reversed with respect to U.

sur_cyl(#2,#1,50,1,vec(2,5,10));

Sweeps the curve 50 units in the direction of (2,5,10).

Comments

The parameter of the profile becomes the U-direction of the surface and V is mapped to the sweeping vector. The optional "reverse" parameter can be used to alter this.