The present invention relates to an automatic figure drawing apparatus and method, and particularly relates to an automatic figure drawing apparatus and method in a computer aided design system (hereinafter abbreviated as "CAD system").
CAD (Computer Aided Design) is an art which has the purposes of making design high in speed, high in quality, and so on. In a CAD system, in order to attain these objectives, it is important to make automatic figure drawing efficient by re-using figure data and using standard parts figure data.
FIGS. 9(a)-(c) are block system diagrams illustrating a conventional automatic figure drawing apparatus.
FIG. 9(a) shows an apparatus for figure drawing by a parametric system, in which data described in a book or the like, such as inner and outer diameters, width, etc. of a bearing are put into a CAD system, and automatic figure drawing is performed in accordance with a drawing program of this CAD system. There have been problems in this case in that if erroneous data is put into a CAD system, an erroneous figure is drawn on the basis of the erroneous data, and in that it is troublesome to input data in accordance with the order of a predetermined format.
The figure drawing by a parametric system is that in which, for example, a parallelogram is expressed by variables a, b and .alpha. as shown in FIG. 8(c); a regular square being expressed if a=b and .alpha.=90.degree., a rectangle being expressed if a b and .alpha.=90.degree., a parallelogram being expressed if a b and .alpha. 90.degree.. Thus, various quadrilaterals different in kind or size can be expressed in accordance with the variables a, b and .alpha.. There is another figure drawing system, which is called a vector data system. This is a system to express a regular square and a regular triangle by variables a' and b' as shown in FIGS. 8(a) and 8(b) respectively; the variable a' can express only a regular square, while the variable b' can express only a regular triangle. That is, for example, if a rectangle is to be expressed, other variables, such as x and y are used. In the above-mentioned example of quadrilaterals, this system has co-ordinates of start and end points of respective lines as data; in the regular square in FIG. 8(a), its four sides are expressed by co-ordinates a1, a2, a3 and a4 of the constant a', and in the quadrilateral in FIG. 8(c), its four sides are expressed by co-ordinates b1, b2, b3 and b4. Those co-ordinates vary if the size of the figure vary.
Being different from a figure drawing method using a figure drawing program as shown in FIG. 9(a), a figure drawing method shown in FIG. 9(b) is such that necessary data is selected, by inputting a command, from figure data (so-called electronic catalog data) stored in advance in a memory means such as a magnetic disk in which a data base is built. Being different from the case where a person reads catalog data values in a book and inputs the read-out catalog data values into a CAD system as shown in FIG. 9(a), figure data entry error is less because of the electronic catalog data on a magnetic medium. There are however problems in that all the necessary figure data must be stored on a magnetic medium, so that a magnetic disk having a large capacity is required which thereby results in a disadvantage in cost and space, and in the case of using floppy disks, the number of the disks becomes large which results in combersome management thereof.
A figure drawing method shown in FIG. 9(c) is a method in which figure data for CAD is produced by a figure drawing program of a parametric system having a data base which is not running on CAD, and the figure data are read into a CAD system to perform figure drawing. In the method, therefore, there has been a problem of troublesome operation in that another CAD system is required and switching is also necessary.