| 摘要 |
PROBLEM TO BE SOLVED: To define the set operation for a complicated curved-surface shape in an easily handleable shape at high speed by performing set operation on polyhedrons constituting the original shape and finding the curved-surface shape from the shapes of the operated polyhedrons. SOLUTION: In this set operation method for three-dimensional curved-surface shape, curved-surface shapes are generated respectively by applying rounding-off operation to polyhedron shapes. The polyhedron shapes and the generated curved-surface shapes are held in a set in a system (STEP 1). Before performing sum-of-sets operation and sum of sets of the polyhedrons, the curved-surface shapes are temporarily deleted. Then difference set operation and product set operation are performed (STEP 2). Of the polyhedron shapes obtained as a result of the set operation, recessed surfaces are divided into projecting surfaces (STFP 3) and the above-mentioned processing is recurrently performed on both divided surfaces. Finally, the set-operated shape of generated curved-surface shapes is obtained by generating the curved-surface shapes by applying rounding- off operation to the projecting surfaces obtained by dividing the recessed surfaces of the polyhydron obtained as a result of set operation (STEP 4). |
