Friday

Selecting overlapping entities.

7 Comments Jan-12-2007 | Posted by Eren Pala | Printable Version | Level |

All of you have ever encountered that when we would like to select only one of two or more number of entities that are overlapping, somehow AutoCAD never selects the entity that we want to select and always selects the one that is last drawn. It becomes a suffering for us to select the one that is drawn before.

For example, we have a rectangle and we would like to draw a 3DFACE over it and then erase the rectangle. When we draw a 3DFACE over the rectangle with the same dimensions, it is impossible to select one entity by using the method of selecting by enclosing window. Always two numbers of entities are selected. Moreover, if we try to select by clicking on it, always the last drawn entity and the 3dface will be selected. When I first started using AutoCAD, I used to move the entity on top a little to the side, and then do whatever I want to do over the one under it and then move back the first entity with the same amount to its original position. As you can see it is a very tedious work to do.

Now, let’s come to the point of making this selection in an easier way. We will select one of the entities that are overlapping as if we are selecting by the usual method. Only difference will be holding down CRTL button while selecting. As you can notice, “Command: [Cycle on]” is written on the command line. During this, every time we click on any location on the screen we want with left mouse button, another of the overlapping objects will be selected one by one. This time, the sequence is just the reverse of what I explained before. First, object that is drawn at the beginning is selected. After that, at every click, the next drawn entity will be selected. And the entity appears in the drawing as highlighted by dashed lines. As soon as the object we would like to select is selected, we exit by pressing enter. After selection is completed, the object we would like to select will be appearing on the screen as selected and “[Cycle off]” will be written in the command line.

Below, you can see the step-by-step explanation of the process by figures:

Drawing order: First of all, the quadrilateral on the left, and then the one on the right is drawn. And finally, the line in their intersection is drawn.

While holding down the CTRL button, I am clicking on the location where the three objects are intersecting. Figure will be as shown above. Now, you can release the CTRL button. When we click on any location on the screen, entity that is drawn next is selected as shown above. 

When we click once more the third entity is selected. 

Unless we confirm the selection by pressing ENTER, there will be a cycle of these overlapping entities by clicking this way. As soon as the entity that we would like to select appears on the screen, we confirm by pressing enter and make the entity selected.