Through Points

Synopsis

obj = BSURF/objlist,numlist1[,VERT[,numlist2]][,DEGREE,num1[,CLOSED],num2[,CLOSED]][,IFERR,label:]

Description

Creates a B-surface using a series of existing points. The points in the list are placed in rows, based on the values in the first number list which represent the number of points desired in each row.

The default creation mode is to define the surface "through" the points. However, the minor word VERT causes the system to interpret the points as control vertices. The optional number list included with the VERT parameter can assign weights to these vertices.

The system automatically decides whether to create a single or multi-patch surface based on the input data.

If the minor word DEGREE is not specified, the system creates a single patch surface. The degrees of a single patch surface are equal to one less than the number of control vertices in that direction.

If DEGREE is specified, the resulting surface possesses the specified degree values. If the number of points/rows specified is greater than the degree plus one in that direction, then the system creates a multi-patch surface.

Parameters

Parameter

Description

objlist

A list or array of existing points which is used to create the surface. The surface either passes through the points or is controlled by them as vertices. The first point in the list represents the first point in the first row, the second point represents the second point of the first row, and so on.

numlist1

A numerical list or array which represents the number of points in each row. The first number in the num list determines the number of points in the first row, as specified in the previous object list.

A single patch surface has degree based on the number of rows and points per row so maximum rows and points per row is based on maximum degree = 24. A single patch surface can have from 2 to 25 rows, with each row containing from 2 to 25 points. The degree of the surface in the U direction is one less than the largest number of points in a row.

A multi-patch surface is not limited in the number of rows and points per row. The degree of the surface can vary between 1 and 24 in either U or V directions. The minimum number of points in any row is forced to be one point greater than the surface degree in the U direction. The minimum number of rows is forced to be one greater than the degree of the surface in the V direction.

VERT

Minor word that indicates that the points in the object list represent control vertices.

numlist2

A numerical list or array which contains the positive weights which is assigned to each corresponding point in the object list.

DEGREE

Minor word that indicates that the degree of the surface is to be specified causing a multi-patch surface to be created unless the degree values meet the requirements of a bezier surface.

num1

A positive numerical value or variable which represents the degree of the surface in the U direction.

CLOSED

Minor word which indicates the surface is to be closed in the U direction.

num2

A positive numerical value or variable which represents the degree of the surface in the V direction.

CLOSED

Minor word which indicates the surface is to be be closed in the V direction.

IFERR,label:

Specifies a label to which program execution jumps if the system cannot create the surface from valid data. This may occur if you are trying to create an extremely large multi-patch surface with varying row counts.

Parameter	Description
objlist	A list or array of existing points which is used to create the surface. The surface either passes through the points or is controlled by them as vertices. The first point in the list represents the first point in the first row, the second point represents the second point of the first row, and so on.
numlist1	A numerical list or array which represents the number of points in each row. The first number in the num list determines the number of points in the first row, as specified in the previous object list. A single patch surface has degree based on the number of rows and points per row so maximum rows and points per row is based on maximum degree = 24. A single patch surface can have from 2 to 25 rows, with each row containing from 2 to 25 points. The degree of the surface in the U direction is one less than the largest number of points in a row. A multi-patch surface is not limited in the number of rows and points per row. The degree of the surface can vary between 1 and 24 in either U or V directions. The minimum number of points in any row is forced to be one point greater than the surface degree in the U direction. The minimum number of rows is forced to be one greater than the degree of the surface in the V direction.
VERT	Minor word that indicates that the points in the object list represent control vertices.
numlist2	A numerical list or array which contains the positive weights which is assigned to each corresponding point in the object list.
DEGREE	Minor word that indicates that the degree of the surface is to be specified causing a multi-patch surface to be created unless the degree values meet the requirements of a bezier surface.
num1	A positive numerical value or variable which represents the degree of the surface in the U direction.
CLOSED	Minor word which indicates the surface is to be closed in the U direction.
num2	A positive numerical value or variable which represents the degree of the surface in the V direction.
CLOSED	Minor word which indicates the surface is to be be closed in the V direction.
IFERR,label:	Specifies a label to which program execution jumps if the system cannot create the surface from valid data. This may occur if you are trying to create an extremely large multi-patch surface with varying row counts.