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Easy Method for Drawing Perspective Figures on a Graphic Editor

IP.com Disclosure Number: IPCOM000113561D
Original Publication Date: 1994-Sep-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 4 page(s) / 105K

Publishing Venue

IBM

Related People

Asaka, S: AUTHOR [+2]

Abstract

It is very difficult to draw perspective figures by using a graphic editor on a computer system, because editors do not support any techniques for drawing perspective relations among graphic primitives. Disclosed is an easy method of overcoming this problem. The method applies to the editing operations of a graphic editor technique for drawing figures in perspective by using a Vanishing Point (VP).

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Easy Method for Drawing Perspective Figures on a Graphic Editor

      It is very difficult to draw perspective figures by using a
graphic editor on a computer system, because editors do not support
any techniques for drawing perspective relations among graphic
primitives.  Disclosed is an easy method of overcoming this problem.
The method applies to the editing operations of a graphic editor
technique for drawing figures in perspective by using a Vanishing
Point (VP).

      There are two main types of perspective drawing method.  The
first deals with one VP.  Briefly, the operations for drawing
perspective figures on a graphic editor are as follows:
  1.  A user first sets up a VP on the screen by using a pointing
       device such as a mouse.
  2.  Graphic primitives are drawn by using perspective drawing
      techniques implemented on a graphic editor, as described later.
      Those graphic primitives are constrained by a VP.
   3.  Perspective graphic primitives are also edited, which are
       similarly constrained by the VP.

      The second types of method for drawing perspective figures
deals with two Restriction Points (RPs) on the horizon.  A user draws
perspective figures by using graphic primitives that are constrained
by two RPs.  The other operations are almost the same as in method of
the first type:
  1.  First, a user sets up a horizon that passes through the VP, and
      sets up two RPs separated by an appropriate interval.
  2.  Graphic primitives are deawn by using perspective drawing
      techniques implemented on a graphic editor.  Those graphic
      primitives are constrained by RPs.
  3.  Perspective graphic primitives are also edited, which are
      similarly constrained by RPs.

      Next, the detailed drawing operations for perspective figures
are explained for each type of method.  These operations should be
supported by a graphic editor.  Fig. 2: Example of drawing a
persective rectangle by using restriction points on the horizon
  1.  Drawing operation using a VP

          For a straight line segment - First, a user should sets up
    an appropriate VP on the screen if he/she starts a perspective
    graphic drawing mode that is supported by a graphic editor.  An
    operation for drawing a line segment is as follows:  In a
    perspective graphic drawing mode, a user first specifies the
    starting position of a line segment by using a pointing...