Monday, December 15, 2014

Commands for Drawing Entities

Once the drawing environment has been set, these commands are used to actually draw the entities.
· Line: Allows for the sequential drawing of one or more straight lines. Once engaged, this command elicits a prompt of “From Point”., at which point the user specifies a starting point for a line, or they may press RETURN, which starts the line at the end of the previous line or arc that was drawn. Next, the prompt “To Point” is displayed, allowing the user to specify a sequence of points to which the line will extend. They may also type the letter C to close the polygon, or the letter U to undo the previous line segment, or they may simply press RETURN to complete the command.
· Point: Draws a single marker/point, which is, by default, a single dot, but may be changed to something else if desired.
· Circle: Draws a circle by letting the user specify the center point, then dictating the circle’s size by entering a value for either the circle’s radius or its diameter. Another option to creating a circle with this command is to specify three points on the circle’s circumference, two end – point of its diameter, of its radius along with two other lines or circles to which the new circle will be tangential.       
· Arc: This command draws arcs, and, like circles, may be dictated in one of several ways. This various methods for constructing arcs with this command are as follows.
i)             Specify three different points.
ii)            Starting point, center and end point.
iii)           Starting point, center, and included angle.  
iv)           Starting point, center and length of chord.
v)            Starting point, ending point, and radius.
vi)           Starting point, ending point, and starting direction and finally.
vii)         Starting point and direction of previous line or arc, plus ending point.
· Ellipse: Ellipse are constructed by specifying the two end points of one of the major or minor axes, followed by a distance value defining half the length of the other axis.
· Pline: Draws 2D polylines, which are continuous sequences of straight lines and / or arc segments with varying line length, dictated by the user. You are able to close a polyline to form a polygon. This AutoCAD 2D fundamentals will help you  navigate  the Pline command and others. It also may be helpful to know the Polylines may be exploded into separate line and arc entities if necessary.
· Polygon: Draws regular polygons by entering the number of edges, then specifying the shape;s center and radius, or by locating the endpoints of any of its edges. Once created, polygons arc to be treated as closed polylines.   
· Hatch: Within one or many closed boundaries, a cross hatch pattern may be created with the Hatch command. The boundaries must be well defined, otherwise, the cross hatch may leak out unexpectedly. The user may select predetermined patterns supplied by AutoCAD, or they mnay enter their own and add them to the set that’s already there.      
· Bhatch: A newer command in the AutoCAD quiver, it helps the user to better use the previously discussed Hatch command. It supports boundary hatching, allowing the user to pick points that is adjacent to the boundary they wanted, and this new command lets AutoCAD search for the nearest entity, then constructs a closed boundary by tracing in a counterclockwise fashion to look for intersection points as well as connecting liens or arcs. Bhatch is convenient in that it allows the user to preview adjustments without having to start over each time.                   

· Dtext: Allows you to draw text dynamically, changing text height and rotation, allowing it to be moved, centered, stretched between two points, aligned, overscored, have symbols added, fonts changed, etc.  

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