Method to animate on a computer screen a virtual pen which writes and draws

摘要

A method to animate on a computer screen a virtual pen which writes and draws on a virtual blackboard in order to simulate a real pen writing on a real blackboard. Graphemes and drawings (50) are created by specifying a subset of knot points (106, 107, 108, 109) from the set of points forming the lines (50) to draw. All the attributes concerning the knot points, as coordinates (201), pauses, speed, thickness, etc., are stored in a file. Subsequently the user types on the keyboard the word to write or selects from a list the drawing to draw. At this point all the attributes of the knot points of the graphemes to write or of the drawing to draw are retrieved from the file and interpolated, and the data obtained are used to animate a virtual pen in such a way it writes and draws looking like a real pen, pausing at the sharp angles, detaching from and landing on the writing surface of the virtual blackboard, varying the thickness and the speed of drawing, using block letters or joined-up writing.

主权项

1. A method to animate on a screen a virtual pen, said method configured for generating on said screen an output consisting of said virtual pen writing a drawing or grapheme by means of lines, in such a way that said lines are written slowly on said screen by said virtual pen in order to mimic the way a teacher would write said drawing or grapheme on a blackboard; comprising the steps of:
creating the drawing/grapheme as a sequence of line portions separated by knot points, each knot point having at least a pair of coordinates; attributing to each knot point a parameter selected among: kind of interpolation and relative weights, virtual pen status up/down from the writing surface, duration of a possible pause, writing speed downstream of the knot point, thickness of the line downstream of the knot point, or a combination thereof; storing said knot points and said parameters attributed to each knot point for each drawing/grapheme to be written; generating from said stored knot points and parameters an output comprising a determined trajectory that passes through all said knot points; said determined trajectory being formed by visible line portions and invisible line portions between said knot points; said determined trajectory taking into account the values of said parameters of said knot points and/or the values of said parameters interpolated between said knot points; causing said virtual pen to write slowly said determined trajectory to mimic the way a teacher would write said trajectory on a blackboard.