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NURBS mesh

A NURBS mesh is a series of NURBS patches. The NURBS mesh is described in a .nrb file. following this format.

Look at the definition of a .nrb file:

{ NURBS

{ patch

orderx 4;

ordery 4;

dimx 4;

dimy 4;

{ 0; 1; 2; 3; 4; 5; 6; 7; }

{ 0; 1; 2; 3; 4; 5; 6; 7; }

(1.40000, 0.00000, 2.40000),1;

(1.40000, -0.78400, 2.40000),1;

(0.78400, -1.40000, 2.40000),1;

(0.00000, -1.40000, 2.40000),1;

(1.33750, 0.00000, 2.53125),1;

(1.33750, -0.74900, 2.53125),1;

(0.74900, -1.33750, 2.53125),1;

(0.00000, -1.33750, 2.53125),1;

(1.43750, 0.00000, 2.53125),1;

(1.43750, -0.80500, 2.53125),1;

(0.80500, -1.43750, 2.53125),1;

(0.00000, -1.43750, 2.53125),1;

(1.50000, 0.00000, 2.40000),1;

(1.50000, -0.84000, 2.40000),1;

(0.84000, -1.50000, 2.40000),1;

(0.00000, -1.50000, 2.40000),1;

}

}

.

This file contains only a patch, but you can have .nrb files with more patches.

orderx and ordery are the order of the surface for x and y parameters.

dimx and dimy are the dimension of the array of control points.

The two sections without names are the knot section for x and y parameter; the follows a the list of control points, in the form:

( x , y , z ) , w;

where w is the weight.

If you have .nrb file you can add it to a .rt file in the same way that a .brp file.


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