Читать книгу AutoCAD For Dummies онлайн

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 It’s possible for a drawing file to contain much more than you can see at any one time. The computer screen is not really the drawing; it is just a viewer that lets you look at all or part of the drawing file.

AutoCAD uses the Cartesian coordinate system to define all locations in the drawing. This includes things such as the starting and ending points of lines, the centers of circles, the locations of text notes, and so on. Cartesian coordinates are named for French philosopher René Descartes, who is famous for statement “I think, therefore I am,” although today he might say, “I tweet, therefore I am” — although tweeting doesn’t always involve thinking.

In his Discourse on Method, Descartes, wearing his mathematician’s hat, came up with the idea of locating any point on a planar surface by measuring its distance from the intersection of a pair of axes (called, by convention, the X-axis and the Y-axis). (That’s axes as in more than one axis, not several tools for chopping wood.) By convention, the intersection of these axes are perpendicular to one another, and their intersection point is identified as 0,0 — or the origin.