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Snapping in TAD and CAD. <break time=“750ms”/>
All CAD software have many snap commands. Such as snapping to vertices <break time=“450ms”/> (that is; corners). intersection points, nearest points, mid-points and so on.
Before understanding the concept of “snaps”, we need to understand essentially why they are needed. Both in TAD as well as CAD.
In CAD software; the mouse cursor plays a crucial role in guiding the graphic shape creation and editing actions.
The draftsman can easily shift his focus to any graphic entity; at will. Remember that a CAD software does not understand the logic of what you are designing. Designing happens purely in the mind of the human only when you use CAD.
However, the CAD software is ever ready to handle the graphical entities that were drawn by the draftsman. That human is free to pick any graphical entity with his mouse. The CAD software does a good job to freely allow the draftsman whatever editing or creation action that he may invoke.
In order to ensure that the editing happens accurately; the CAD software gives the draftsmen the capability to “snap” the mouse to the correct points just as the editing is going on.
Those familiar with CAD software would know all this.
TAD does not work like CAD. Firstly; the mouse cursor is simply a “mouse cursor” most of the time. It is used to click on the user-interface elements such as menu items, buttons, etc. It can be used to select the objects in the TAD model. It can also drag or rotate objects. But except for those, the mouse cursor does NOT participate in either creation nor editing of the model.
For helping you with creation and editing; there are three special “persons” on the site. Yes, you can actually think of three human beings present right inside the model. Think of this like a computer game; where there are three persons simulated on the screen.
These three persons are shown using 3 shapes. The first person is called the “architect”. It looks like a tilted capital letter <break time=“350ms”/> “A” <break time=“350ms”/> placed inside a square. The other two persons are called “helpers” The first helper is shown as a red square dot. The second helper is a blue circular dot.
The visual size of the simulated architect on the screen can zoom up and down; depending on the zoom setting of the TAD model. The visual appearance of the two helpers do not change with the zoom setting.
Now where does the snapping happen in TAD? Is it done with the mouse?
No!
As explained earlier; the mouse is never really used in TAD as one would use in CAD software.
Instead the location of the simulated architect is the point of interest for TAD. And therefore; the snap commands would shift that architect precisely.
Snapping in CAD software happens in the middle of the editing. But in TAD; the architect is snapped into the correct location <break time=“250ms”/> BEFORE <break time=“250ms”/> any editing/creating happens. Those starting with TAD should get accustomed to this difference from CAD.
Remember; the simulated architect inside TAD is always located at some visible location.
By the way; this architect can never be moved out of visibility. If you happen to zoom to another part of the site; where the simulated architect was absent; you would find that magically TAD would shift the architect into visibility: It would get transported to the centre of the new view of the model; even though the architect was not located there in the earlier view.
Why should snap work on this architect? The reason is; that architect is pointing out the exact point where creation and/or editing happens next in TAD.
TAD allows five types of snaps on this simulated architect. It can snap the architect onto the location of the first helper. Or the architect can be snapped to the second helper. Or the architect can be snapped to the foot of the perpendicular of that infinite line which contains the edge that has the two helpers.
TAD also allows the architect to snap on a point of intersection between two edges. If that be the case; then one of the edges should be the one with the current helper.– and also; the architect should be roughly located visually on the intersection.
Lastly; TAD allows the architect to snap on to any corner in the model. Again, for this snap to happen; the architect should be roughly located visually on the corner you expect to snap to.
What does “roughly located architect” mean? Remember that the icon used for this simulated architect is drawn inside a square. For the last 2 snaps; you need to drag and drop that architect so that the expected point is somewhere within the square of the architect's icon.
Summary:<break time=“500ms”/>
Snaps in drafting software happens in the middle of the editing or creation action. In TAD; snapping has to be done on the simulated architect, BEFORE you decide to invoke an editing or creation action. The architect can also be shifted precisely using mathematical commands – but let me explain that later.