Writing instrument

A method for tracking a writing instrument when contacting a writing surface, the method comprising steps of:

• providing a set, the set comprising:
• the writing instrument;
• a holder for a smart device;
• and
• the smart device, wherein the writing instrument includes:
• a body having an axis with a first window made of a transparent material and a second window made of the transparent material, wherein the first window and the second window extend annularly around the axis;
• a writing element with a writing tip, a first visual mark, and a second visual mark;
• and
• a shutter coupled to the writing tip, wherein the second window is separated from the first window along a length of the body such that the first window is closer to the writing tip than the second window;
• placing the smart device onto the holder;
• orienting a camera of the smart device toward a 3D space comprising the writing surface;
• and
• detecting a presence of the first visual mark and the second visual mark, wherein the first visual mark and the second visual mark are visible to the camera, through the first window and the second window respectively, when the writing tip is in contact with the writing surface, wherein the first visual mark and the second visual mark are hidden from the camera, within the body of the writing instrument, when the writing tip is fully extended but distant from the writing surface, wherein the shutter is actuated and opened to reveal the first visual mark and the second visual mark to the camera when the writing tip is in contact with the writing surface, and wherein the shutter is actuated and closed to hide the first visual mark and the second visual mark from the camera when the writing tip is not in contact with the writing surface.

A computer program including instructions for tracking a writing instrument when contacting a writing surface by a computer or smart device detachably coupled with a holder, the computer program comprising steps of:

• detecting a presence of at least one visual mark of the writing instrument, wherein the writing instrument includes a body having an axis with at least one transparent window and a writing element, wherein at least one transparent window is made of a transparent material, wherein the at least one transparent window extends annularly around the axis, wherein the writing element includes a writing tip, a reservoir containing ink or leads, a shutter coupled to the writing tip, and the at least one visual mark,
• wherein the body includes a rear barrel and a front part, wherein the at least one transparent window is formed in a wall of the rear barrel, wherein the front part is configured to circumferentially couple and decouple to the rear barrel, and wherein the front part is closer to the writing tip than the rear barrel,
• wherein the computer or smart device detachably coupled with a holder includes a camera, wherein, when the computer or smart device is coupled with the holder, the camera is oriented towards a 3D space comprising the writing surface,
• wherein the at least one visual mark is visible to the camera, through the at least one transparent window, when the writing tip is in contact with the writing surface and the at least one visual mark is hidden from the camera, within the body of the writing instrument, when the writing tip is distant from the writing surface, and
• wherein the shutter is actuated and opened to reveal the at least one visual mark to the camera when the writing tip is in contact with the writing surface and the shutter is actuated and closed to hide from the camera the at least one visual mark when the writing tip is not in contact with the writing surface.