Numerical controller

A numerical controller that displays, on a display device, a three-dimensional model of a workpiece after machining based on CAD data in association with a machining program generated based on the CAD data, the numerical controller comprising:

• an optimum data amount calculation unit that calculates an optimum value of at least one of the number of vertices and the number of polygons of a workpiece after machining, the number of vertices or the number of polygons being extracted from the CAD data;
• a three-dimensional data reduction unit that reduces the number of vertices or the number of polygons of the workpiece after machining extracted from the CAD data based on the optimum value of the number of vertices or the number of polygons of the workpiece after machining calculated by the optimum data amount calculation unit;
• a three-dimensional model generation unit that generates a three-dimensional model of the workpiece after machining based on the vertices or the polygons reduced by the three-dimensional data reduction unit;
• and
• a display unit that generates display data for displaying the three-dimensional model generated by the three-dimensional model generation unit and display the generated display data on the display device.