auto cad 的 (TRIM)點用?

Click the icon and press F1 key.....

Trims objects at a cutting edge defined by other objects
Command line: trim
Current settings: Projection = current Edge = current
Select cutting edges...
Select objects: Select one or more objects and press ENTER, or press ENTER to select all objects (implied selection)

Objects that can be trimmed include arcs, circles, elliptical arcs, lines, open 2D and 3D polylines, rays, splines, hatches, and xlines.

Select the objects that define the cutting edges at which you want to trim an object, or press ENTER to select all objects as potential cutting edges. Valid cutting edge objects include 2D and 3D polylines, arcs, circles, ellipses, lines, layout viewports, rays, regions, splines, text, and xlines. TRIM projects the cutting edges and the objects to be trimmed onto the XY plane of the current user coordinate system (UCS).

Select object to trim or [Project/Edge/Undo]: Select an object to trim, press SHIFT and select an object to extend, or enter an option

When AutoCAD prompts you to select boundary edges, you can press ENTER and select the object to be trimmed. AutoCAD trims the object against the nearest candidate. You can use only the single, crossing, fence, and implied selection options to select boundaries that include blocks.

Object to Trim
Specifies the object to trim. AutoCAD repeats the prompt for the object to trim so that you can trim multiple objects. Pressing SHIFT while selecting an object extends it to the nearest boundary rather than trimming it. Pressing ENTER ends the command.

If the selection point is between the end of the object and a cutting edge, TRIM removes the portion of the object that extends beyond the cutting edge. If the selection point is between two cutting edges, the portion between is deleted and the portions outside are preserved, turning one object into two.

AutoCAD trims 2D wide polylines at their center lines. If the polyline is tapered, the width at the cutting edge is the same after trimming. The ends of a wide polyline are always square. Cutting a wide polyline at an angle causes portions of the end to extend beyond the cutting edge. Trimming a spline-fit polyline removes the curve-fit information and changes the spline-fit segments into ordinary polyline segments.

Project
Specifies the projection AutoCAD uses when trimming objects.

Enter a projection option [None/Ucs/View] : Enter an option or press ENTER
None

Specifies no projection. AutoCAD trims only objects that intersect with the cutting edge in 3D space.

UCS
Specifies projection onto the XY plane of the current UCS. AutoCAD trims objects that do not intersect with the cutting edge in 3D space.

View
Specifies projection along the current view direction. AutoCAD trims objects that intersect the boundary in the current view.

Edge
Determines whether an object is trimmed at another object's implied edge or only to an object that intersects it in 3D space.

Enter an implied edge extension mode [Extend/No extend] : Enter an option or press ENTER

Extend
Extends the cutting edge along its natural path to intersect an object in 3D space.

No Extend
Specifies that the object is trimmed only at a cutting edge that intersects it in 3D space.

Note When trimming hatches, do not set Edge to Extend. If you do, gaps in the trim boundaries will not be bridged when trimming hatches, even when the gap tolerance is set to a correct value.

Undo
Reverses the most recent change made by TRIM.

2007-12-19 02:09:59 補充：
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