Producing a blending function mesh for inferring a blending function for a t-nurccs surface model defining a smooth surface

A system comprising:

• a non-transitory storage medium having instructions of a computer aided design program stored thereon;
• and
• one or more data processing apparatus able to run the instructions of the computer aided design program to perform operations comprising:
• obtaining a control mesh for a T-spline surface;
• generating a blending function mesh for inferring a blending function for a control point of the T-spline surface by defining a topology for the blending function mesh, wherein defining the topology for the blending function mesh comprises
• defining a central vertex and central edges of the blending function mesh that are inferred from the control mesh, and
• generating further topology for the blending function mesh by directly inferring further faces and edges for the blending function mesh from the defined central edges of the blending function mesh;
• inferring the blending function for the T-spline surface from the generated blending function mesh;
• and
• providing the inferred blending function for use for computing the T-spline surface.

A non-transitory computer-readable medium encoding instructions operable to cause data processing apparatus to perform operations comprising:

• obtaining a control mesh for a T-spline surface;
• generating a blending function mesh for inferring a blending function for a control point of the T-spline surface by defining a topology for the blending function mesh, wherein defining the topology for the blending function mesh comprises
• defining a central vertex and central edges of the blending function mesh that are inferred from the control mesh, and
• generating further topology for the blending function mesh by directly inferring further faces and edges for the blending function mesh from the defined central edges of the blending function mesh;
• inferring the blending function for the T-spline surface from the generated blending function mesh;
• and
• providing the inferred blending function for use for computing the T-spline surface.