The distortion consists of "point" distortion. Namely, the distortion involves determining a point in the image to serve as the "dragging" point and another point to serve as the target point, or the point up to which the dragging point will be pulled.
The dialog for determining the two points reads input from the mouse in terms of the coordinates of the canvas.
The two columns on the left indicate the x-y coordinates of the "dragging" point, and the two columns on the right indicate the x-y coordinates of the objective point. Both columns are updated interactively by a click of the mouse.
The algorithm used to distort follow the Molecular Dynamics algorithm by applying a force to the initial point, in the direction of the final point. The points that make up the image are tied to one another by springs with constant "k" and a hard core interior. The options for the grid springs, update step, and viewing options are setup by the options dialog.
|The "stiffness" tab sets the spring constant "k" and the size of the hard core of the grid points.||The "update" tab sets the frequency of updating in the screen as the distortion occurs, and the size of the step that the hard cores move.||The "view" tab sets the display parameters, whether to draw the picture as a solid image or a mesh, and whether to show the hard cores as circles of radius equal to their size.|