Make an existing block into a mask block

[igroup.kskoog]

Can I take an existing block I already have and turn it into a mask block? We use custom 2x4 fluoroescent light fixture blocks that we want to be masked. I tried to do a block edit and covert the 2x4 polyline edge to mask and doesn't mask Even when I attach to ceiling grid (using ceiling grid program). Autocad Architecture 2014 is what I am using.

Thanks in advance

Kory Skoog

CADD Technician

[MilneJB]

Is there any reason not to use a wipeout instead?

[David_W_Koch · Accepted solution]

Draw a closed polyline for the area you want the Mask Block to mask. (I would do it on Layer 0, with ByBlock properties.) Insert an instance of your existing block (AutoCAD block or ACA Multi-View Block; the latter can be set up to respond to the Display System) and position it as desired relative to the closed polyline.

You cannot directly "convert" a block or Multi-View Block into a Mask Block, but you can create a Mask Block Definition and use the block or Multi-View Block as the "additional graphics" associated with that definition.

In the Style Manager, create a new Mask Block Definition. Right click and choose Set From.

The Style Manager will disappear and you will be prompted to select a closed polyline, spline, ellipse or circle. Select the polyline that represents the extents of the masking.

Assuming that you have no other mask-defining "rings" to add to the Mask Block, respond "No" to the Add another ring? prompt.

Indicate the insertion base point for the Mask Block.

Now choose the instance of your current block in repsonse to the Select additional graphics prompt. When done selecting additional graphics, press ENTER.

The Style Manager will reappear. Select OK to ratify the new Mask Block Definition in your drawing. Save the drawing file.

You can now add the new Mask Block Definition (type MASKADD at the Command prompt) and place an instance. If it is on a ceiling grid (or other AEC object), after the instance is placed, select it, and, on the Mask Block Reference contextual ribbon tab, on the Modify panel, choose the Attach Objects tool. Select the ceiling grid, note the currently active Display Representation(s) for ceiling grids in the Select Display Representation dialog. If more than one is active, select the one to which you want the mask to apply. Select OK and the mask will be applied.

You can find a more detailed explanation, with some screen captures, in these blog articles, if you are interested:

http://architects-desktop.blogspot.com/2012/12/aca-ceiling-grids-mask-blocks.html
http://architects-desktop.blogspot.com/2013/01/aca-ceiling-grids-creating-mask-block.html

[David_W_Koch]

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@MilneJB wrote:

Is there any reason not to use a wipeout instead?

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I have had issues with plotting wipeouts in the (distant) past, and have not used them much recently.  Perhaps you have not experienced problems with wipeouts.  Here are some features of mask blocks which you may or may not see as a reason to use one over a wipeout:

1.  I have not had problems when plotting Mask Blocks.  We have our plot settings set to merge pens, so that if a halftone (screened) line is on top of a full intensity line, the merging of the pens results in the full intensity line showing through the screened line.  This has defeated the wipeout effect.  I have also had wipeouts plot black.

2.  Mask Blocks only work on AEC objects.

3.  Mask Blocks only mask an AEC object to which it is attached, and only for the selected Display Representation of that object.  This allows for a Mask Block to mask one object but not others.  For example:  I can use a Mask Block to mask a portion of a Ceiling Grid while allowing a column center line that passes through the Mask Block to remain in view; a Wipeout would mask both, without playing with draw order.

4.  When externally referencing a file that contains wipeouts, you cannot control the draw order of the objects within the external reference and sometimes that does not work out the same way as in the main file and the masking is not as desired.

If wipeouts work for you and your workflow, there is no reason to switch to Mask Blocks.  I find Mask Blocks are quite useful for ceiling-based objects when using Ceiling Grids, particularly if you have objects that span more than one grid cell.

[igroup.kskoog]

That worked. I was hoping to have fewer steps that's all. We have over 500 light fixtures and now wanted to attach and mask out where we have 2x2 grids without reinserting. I will try a replace block command and see if that will work. Thanks again.

Kory Skoog

CADD Technician

[Dana.Baumann]

For me using wipeout was the easiest