公开(公告)号：FR2656717B1

公开(公告)日：1994-02-04

申请号：FR9100007

申请日：1991-01-02

Applicant: APPLE COMPUTER INC

Inventor： VENOLIA DANIEL S.

IPC: G06F3/033 ,  G06F3/048 ,  G09G5/08 ,  G09G5/32

Abstract: A method for changing the orientation of a graphic object in response to changes in the variable position of that object on the display of a computer is disclosed. The position of the graphic object on the display is determined by the position of a control point having a fixed position in relation to the object and a variable position in relation to the display. The control point is operative to change its position in response to translational signals received by an interactive control device, and the computer is operative to display the object at each position of the control point. A change in the orientation of the object to be displayed at the new position of the control point is determined by establishing a following point having a fixed position with respect to the object and a variable position with respect to the display, and tracking the variable position of the following point behind the path of the motion of the control point. The path of the control point is tracked by the following point by determining the direction and magnitude of change in a vector extending between the control point and the following point and then changing the variable position of the following point to normalize the magnitude of the vector in that direction of change.