Three-dimensional arrow for computer graphics
AssigneeAutodesk, Inc.
InventorKenneth Jamieson Hill
Life of this patent
Estimating the term…
Abstract
A method, apparatus and article of manufacture for generating and rendering arrowheads that approximate the direction of the arrowhead. A base and an axis vector for the arrowhead are created, and a view direction vector, approximating the direction that a user of a computer is viewing the arrowhead, is determined. The angle between the axis vector and the view direction vector is calculated, and the arrowhead is displayed rotated by the angle between the view direction vector and the axis vector. Silhouette lines and portions of the base are selectively displayed depending on the angle that the arrowhead is viewed from.
Claims12
A method for generating an arrow for display on a computer wherein the shape of the arrow approximates a direction that the arrow is pointing, comprising the steps of:
- (a) computing a base for the arrowhead using an axis vector for the arrowhead, the axis vector being substantially normal to the base of the arrowhead and pointing from a center of the base to an apex of the arrowhead;
- (b) determining an angle between a view direction vector and the axis vector, the view direction vector being substantially normal to a three-dimensional frame of reference displayed on the computer;
- and
- (c) displaying the arrowhead on the computer wherein the arrowhead is rotated by the angle between the view direction vector and the axis vector.
An apparatus for generating an arrowhead for display on a computer wherein the shape of the arrowhead approximates a direction that the arrowhead is pointing, the apparatus comprising:
- (a) a computer;
- (b) means, performed by the computer, for computing a base for the arrowhead;
- (c) means, performed by the computer, for determining an axis vector for the arrowhead, the axis vector being substantially normal to the base and pointing from a center of the base to an apex of the arrowhead;
- (d) means, performed by the computer, for determining an angle between a view direction vector and the axis vector, the view direction vector being substantially normal to a three-dimensional frame of reference displayed on the computer;
- and
- (e) means, performed by the computer, for displaying the arrowhead on the computer wherein the arrowhead is rotated by the angle between the view direction vector and the axis vector.
A program storage device, readable by a computer, tangibly embodying one or more programs of instructions executable by the computer to perform method steps of generating an arrowhead with a computer wherein the shape of the arrowhead approximates a direction that the arrowhead is pointing, comprising the steps of:
- (a) computing a base for the arrowhead;
- (b) determining an axis vector for the arrowhead, the axis vector being substantially normal to the base and pointing from a center of the base to an apex of the arrowhead;
- (c) determining an angle between a view direction vector and the axis vector, the view direction vector being substantially normal to a three-dimensional frame of reference displayed on the computer;
- and
- (d) displaying the arrowhead on the computer wherein the arrowhead is rotated by the angle between the view direction vector and the axis vector .
Dependencies are inferred from the claim text.