Online QCad Newbie
is our listing of typical train wreck issues while learning QCad on
setup requirements to get started
The object snap toolbar automatically appears when the previous drawing tool selection choice can use this object snap concept for new entity placement. It also appears automatically when a previous tool selection choice can use this object snap concept to modify or relocate an existing entity. It can also be called upon with a right arrow in a tool list on some occasions. This is very confusing for a beginner, but makes perfect sense after you learn the reason for object snaps.
Basically you can relocate a previous entity or draw a new entity relative to points on or nearby to previously drawn entities. This allows the new entity to have a precise physical location on the drawing that is relative to some previous entity. The snap object tool icons depict pictures that show the points of relationship for each tool.
You can also combine the relative zero point with a previous entity snap point to derive a new snap point relative to both the relative zero point and the selected entity point. This is much harder to say than it is to actually do. This is called a snap restriction. To understand snap restrictions, you must first understand the relative zero point.
The relative zero point is that little red dot which follows you around as you draw entities. This little red dot always resides at the last point you set. For example, when using the line tool, you click for the first point on the new line, and then you click on the last point of the new line. Then QCad draws the line on the screen connecting those two points. The relative zero point is the point that terminated this new line. This is a good thing because you can now continue a new line segment in any direction from this relative zero point and a single mouse click sets the next line segment. That click also resets the relative zero point to the end of the newest line drawn. This is why I say that the relative zero point follows you around. The next starting point is by default, relative to the last drawing point. This results in a chain of actions with common physical drawing position relationships.
This relative zero point "puppy dog" can be broken with a right click of the mouse, or by selection of a different tool. This relative zero point can also be locked so it does not follow you around. This lock tool is found in the Snap Objects toolbar. While the relative zero point is locked, it will no longer follow you around, but it can still be moved manually with another tool in the Snap Object toolbar even while it is locked.
When you lock and reposition the relative zero point, you can basically combine this locked relative zero point with a snap object point of a previous entity to create a new virtual snap object point that is basically an offset snap object point. To reduce the confusion lets use an example. First we must understand that an orthogonal tool restricts motion either in a vertical line, a horizontal line, or in all four 90 degree directions. Suppose that you want to place a point of a new entity that is exactly 1-inch below the end-point of a previous line. Just set the locked relative zero point 1-inch below the desired end-point of that line (doesn't have to be under the previous line either), and then select the end-point of that previous line using the snap restrictions orthogonal vertical tool, and the new snap object point will be 1-inch below the end point of the previous line. In other words, the new snap object point will be offset 1-inch below that previous line end-point while using the vertical orthogonal tool, because the orthogonal snap restriction tool causes the relative snap object point to fall precisely under the previous line point.
With this snap object understanding, all your drawing tools will make much more sense as you learn how to use those drawing tools. By the way, there is a new button in the <object snap> tools called <auto>. When you select auto, the snap jumps to the nearest snap entity be it endpoints, midpoints, intersection points, grid points or whatever is near by. This could be very useful for many situations, and the Help does not explain what it does.
Snap User Issues
While placing the dimension for an entity, the instructions are quite clear in the help; or are they! Many new users run into this dimensioning problem. Let us use the example of placing an aligned dimension of a line that is drawn at an angle. You select the dimensioning tool <Aligned dimensions> and the toolbar changes to the <Object snap> toolbar as expected. You decide to use the <Snap to endpoints> since you want the dimension of a line. You place the mouse pointer near one endpoint of the line and left click the mouse. This sets one end of the dimension. Then you place the mouse near the other endpoint of the line and left click the mouse again to end the dimension. Isn't life just Grande! But wait a moment, when you try to set the dimension-position, the third mouse click has no effect. What the
Believe it or not, this is the way it is supposed to work! When you selected the <Snap to endpoints> tool modifier for the <Aligned dimensions> tool, it accurately found both endpoints of the line dimension. But now for that third mouse click to set the dimension position, you are no longer near another endpoint, so the third mouse click is ignored. To resolve this issue, you must move the mouse pointer over to the <Object snap> toolbar and select the upper <+> tool which means free positioning without snap limits. Now move the mouse pointer back to the location for the dimension position, and the third dimension mouse click will now work and set the dimension position offset as specified by the third mouse click. Before you learn this, it all seems like un-cooperating magic. Now that you know what is happening, these same issues can occur while using other drawing tools in combination with the <Object snap> toolbar. The snap limits that you select, remain in effect until you change them, or you change the drawing tool. Keep this in mind, and many drawing issues will disappear for the new user.
<Auto snap> to the Rescue
Version 184.108.40.206 and above includes a new <Auto-snap> tool selection on the <Object snap> toolbar. This precious little gem eliminates the problems described above. Instead of having to change <Object snap> tool while you work, just use the new <Auto snap> tool which snaps to most everything.