A new capability in AutoCAD 2011 allows you to set transparency as an object property. You can set transparency Bylayer, Byblock or as a percentage value from 0 to 90. Transparency can come in handy when you have overlapping objects and want to view those underneath.

Caption: Sample drawing from Autodesk illustrates the new transparency property.

You can set transparency for individual objects, just like with other properties such as color and linetype. Setting a transparency value for an individual object overrides the layer transparency setting for that object.

You can access object transparency from a number of places in AutoCAD 2011. The ribbon features a Transparency control and slider in the Properties panel of the Ribbon Home tab. You can also view and change the Transparency value for an object in the Properties palette.

The Layer Properties Manager features a new column for transparency in model space. There is also a new column for transparency (VP Transparency) in layouts and floating model space viewports.

Transparency is an option in the Chprop, Change, -Layer, Vplayer, SetByLayer, and List commands.

Caption: Transparency is an option in the SetByLayer Settings  dialog box.

The new CETRANSPARENCY system variable sets the transparency property for new objects. The default setting for layers and objects is 0 (zero).

If you don’t want transparent objects, use the new button on the status bar to temporarily turn off transparency display. This button governs the TRANSPARENCYDISPLAY system variable (On by default). 

Caption: Use this status bar button to toggle transparency on and off.

Note that this toggle does not affect plotting.

To turn off transparency when plotting, the Plot and Page Setup dialogs both include a checkbox for Plot transparency (PLOTTRANSPARENCY system variable), similar to the behavior for plot styles. When this option is enabled, AutoCAD rasterizes the entire drawing for plotting, slowing down the plotting process.

Caption: Plot transparency option in the Plot and Page Setup dialog boxes controls whether transparency settings are reflected in the plot.

Because of this performance hit, there is a global system variable that turns transparency on and off for all plots. That system variable is quite a mouthful: PLOTTRANSPARENCYOVERRIDE. When PLOTTRANSPARENCYOVERRIDE is set to 0, transparency is off for all drawings when they are plotted. When PLOTTRANSPARENCYOVERRIDE is set to 2, transparency is on for all drawings when they are plotted. As its name implies, PLOTTRANSPARENCYOVERRIDE overrides the Plot Transparency setting in the Page Setup and Plot dialog boxes. Autodesk suggests you use this system variable sparingly because it doesn’t update the Plot and Page Setup dialog box settings, which could cause confusion.

You can now use grips to edit the boundary of a clipped external reference. Ensure that the XCLIPFRAME system variable is set to 1, and then select the clipped xref and grab a grip. In addition to using grips to edit the clipping boundaries, a new grip located at the midpoint of the first edge of the clipping boundary enables you to quickly invert the clipping area. Click the grip to invert the display of the reference clipped inside or outside the boundary.

Caption: Grips allow you to edit xref clipping boundaries in AutoCAD 2009 and up.
When creating clipping boundaries for xrefs, keep these guidelines in mind:

• You can specify a clipping boundary anywhere, but it is always applied planar to the current UCS.
• If you select a polyline, the clipping boundary is applied in the plane of that polyline.
• Images in xrefs or blocks are always clipped within the rectangular extents of the reference. When you apply polygonal clipping to images in xrefs, the clipping boundary is applied to the rectangular extents of the polygonal boundary, not to the polygon itself.

One common complaint about the Ribbon introduced in AutoCAD 2009 is that it lacks any mention of the Express Tools. If this omission is bothersome, one enterprising user has posted an Express Tools CUI replacement to the Autodesk discussion groups. The replacement modifies the standard acetmain.cui to include a ribbon tab and panels for all Express Tools. 

Before installing, be sure to back up your customization files. Also read and follow the installation instructions carefully.

Here’s a nifty mline trick from the Xanadu web site.

To draw multicolored lines in AutoCAD, use the Mlstyle command to define a new multiline style. Define two line elements, both with offset equal to 0 (zero). Set each element to a different color (red and green in our example), and also assign different linetypes to each. For example, set one to DASHED and one to DASHED2.

Caption: Define a new mline style with two elements of different colors.

You may need to experiment with different linetypes to get the results you want, and quite possibly define your own linetypes. Note that you may need to load more linetypes by pressing the Load button.
When you’re done, save the Mline style.

Caption: Note that the preview of the new style shows only one of our colors.

Next, use the Mline command to draw a polyline using your new style. The line that results will be red and green.

Caption: Two-colored mline.

Note that you can create lines of three and even more colors in this manner.