Method for designing a 3D object by using a virtual 3D grid and hand drawn sketches

A non-transitory computer-readable data-storage medium having stored thereon computer-executable instructions that when executed by a computer system cause the computer system to carry out a method for designing a 3D object in a scene, the method comprising:

• a) obtaining a 3D grid of cubes in the scene, said 3D grid of cubes controlling a subdivision surface, said subdivision surface modeling the 3D object;
• b) receiving a user stroke of a curve on at least one external face of at least a cube of the 3D grid of cubes;
• c) determining a first set of cubes which intersect with the curve on the external face, a second set of cubes which is adjacent to the first set of cubes, perpendicularly to the external face, and a third set of cubes, including the first set of cubes and the second set of cubes;
• c′) computing a number of cubes of the 3D grid of cubes on both sides of the cube of the first set of cubes in a plane of the external face, removing, from the scene, a set of cubes on one side which has a lower number of cubes than a set on the other side, and removing the corresponding cubes of the second set of cubes;
• and
• d) for each cube of the third set of cubes, deforming the cube by moving at least one vertex of said cube to fit the curve, thereby deforming the subdivision surface.

A computer system comprising:

• a processor coupled to a memory, the memory storing computer-executable instructions for designing a 3D object in a scene that when executed by the processor cause the processor to be configured to:
• a) obtain a 3D grid of cubes in the scene, said 3D grid of cubes controlling a subdivision surface, said subdivision surface modeling the 3D object,
• b) receive a user stroke of a curve on at least one external face of at least a cube of the 3D grid of cubes,
• c) determine a first set of cubes which intersect with the curve on the external face, a second set of cubes which is adjacent to the first set of cubes, perpendicularly to the external face, and a third set of cubes, including the first set of cubes and the second set of cubes,
• c′) compute a number of cubes of the 3D grid of cubes on both sides of the cube of the first set of cubes in a plane of the external face, remove, from the scene, a set of cubes on one side which has a lower number of cubes than a set on the other side, and remove the corresponding cubes of the second set of cubes;
• and
• d) for each cube of the third set of cubes, deform the cube by moving at least one vertex of said cube to fit the curve, thereby deforming the subdivision surface.