VARKON Version 1.15 1997-10-24

sur_conic - Geometric procedure

Creates a conic lofting surface.


Description

Creates a conic lofting surface. Input data is a number of longitudinal curves (directrices), scalar functions and a spine curve. The cross-section curves (generatrices) will always be of the cur_conic() type. The cross-section curves are defined by intersection points between the longitudinal curves and planes, which are perpendicular to the spine curve.


Syntax

sur_conic(id, spine, lim1, tan1, m1, mcur1, lim2, tan2, m2, mcur2, lim3, ...... :attributes);

REF	id;
REF	spine;
REF	lim1;
REF	tan1;
STRING	m1;
REF	lim2;
REF	tan2;
STRING	m2;
REF	mcur2;
REF	lim3;
REF	....

Principal parameters

id	- Local identity
spine	- Spine curve
lim1	- Limit 1 curve (will be the V= 0.0 curve in the surface)
tan1	- Tangent definition curve 1
m1	- Flag defining the type of mid curve
	Eq. M: Mid curve is a R*3 curve
	Eq. P: Mid curve is a P-value curve
	A function with X= spine length and Y = P value
mcur1	- Mid curve 1
lim2	- Limit 2 curve (will be the V= 1.0 curve in the surface)
tan2	- Tangent definition curve 2

Optional parameters

m2	- Flag defining the type of mid curve
mcur2	- Mid curve 2
lim3	- Limit 3 curve (will be the V= 2.0 curve in the surface)
...	....

Attributes

PEN	- Pen or colour number
LEVEL	- Level number
BLANK	- Visible (0) or invisible (1)
SFONT	- Solid boundary and dashed midcurves (0)
SDASHL	- Dashlength

Example

sur_conic( #10, #1, #2, #3, "M", #4, #5, #6, "P", #7, #8);

Creates a conic lofting surface (type LFT_SUR) with spine curve #1. The number of patches in the V direction will be two since the number of limit curves (#2, #4, #7) and tangent definition curves (#3, #5, #8) is three. The number of patches in the U direction is defined by the segments in the longitudinal curves and the spine.

The mid curve in the first V strip is a R*3 curve and in the second V strip a P value function.


Comments

The created surface LFT_SUR is of the procedural type.