Sketch-based editing of curves

A method for interacting with a user of an interactive graphics system, comprising:

• displaying a curve on a display device;
• providing to the user a smoothing tool operable under control of the user through a graphical user interface;
• receiving a gesture from the user moving the smoothing tool over a part of the curve to indicate a selection of the part of the curve;
• and
• smoothing the selected part of the curve by applying a smoothing filter to the selected part of the curve.

A method of editing a brush stroke in a graphics system in which a brush stroke includes a trajectory curve, an envelope curve, and envelope information, comprising:

• displaying a brush stroke on a graphical user interface;
• editing a trajectory curve of the brush stroke by sketch-based editing, sketch-based editing comprising receiving through the graphical user interface a sketch curve as input and modifying the trajectory curve based on the sketch curve;
• and
• calculating a new envelope curve for a new brush stroke using the edited trajectory curve and the envelope information of the existing brush stroke.

A computer program product stored on a computer-readable medium for interacting with a user editing a curve, the product comprising instructions operable for causing a programmable processor to:

• display an existing curve on a graphical user interface;
• receive through the graphical user interface a sketch curve as input from a user, the sketch curve having two end points and being separately defined from the existing curve;
• define a target section of the existing curve by finding a point in the existing curve nearest each of the end points of the sketch curve, the target section being the part of the existing curve between the found points;
• and
• replace the target section of the existing curve with a new section.

A computer program, residing on a computer-readable medium, comprising instructions for causing a computer to:

• provide to the user a smoothing tool operable under control of the user through a graphical user interface;
• receive a gesture from the user moving the smoothing tool over a part of the curve to indicate a selection of the part of the curve;
• and
• smooth the selected part of the curve by applying a smoothing filter to the selected part of the curve.

A system for editing a brush stroke in a graphics system in which a brush stroke includes a trajectory curve, an envelope curve, and envelope information, comprising:

• means for displaying a brush stroke on a graphical user interface;
• means for editing a trajectory curve of the brush stroke by sketch-based editing, sketch-based editing comprising receiving through the graphical user interface a sketch curve as input and modifying the trajectory curve based on the sketch curve;
• and
• means for calculating a new envelope curve for a new brush stroke using the edited trajectory curve and the envelope information of the existing brush stroke.