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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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