MANIPULATING OBJECTS

INDEX

MANIPULATING OBJECTS

The first point to mention in this chapter is the one related with the selection of objects. Selecting objects in MG can be very simple or, in some way, tricky; and it depends on the number and the type of objects on the screen. Once used to the application, all difficulties desappear, but, I must confess that I have been criticized in relation with this item. So, a clear explanation seems needed. It must be said that there are three ways of selecting an object, and one of them never fails. The simplest way of selection, as has been said, is to click on the object. If this one is "alone" it will change to "red" immediately, so, no trouble. BUT, if the object is "inside" another one, bigger and more recent, its selection by the direct method is not possible. In this last (and only important) case, there are two option. Once more the simplest is to click the "double-arrow" button. Each time this button is clicked, a different object is selected. Theoretically, this would be enough for the goal, but if the screen is plenty of different objects, it is needed to click many times, what can be cumbersome and boring. And, what is worse, it is possible to click too quickly and "overpass" the right object. Then the whole operation must be repeated. A small improvement is to use the "Q" key instead of the button. The effect is the same but it is easier and simpler.

A third possibility, and the one used by myself almost always, is to use the "mouse-dragging" method. As has been said before, it is possible to select an object by clicking and dragging the mouse -in reset state- over it in such a way that the object is included in its totallity inside the red rectangle visible as long as the button of the mouse is not released. With some short practice, it is very simple to use this method. The only point to remember is to include ONLY the object wanted in its totallity. So, some simple technique must be acquaired. The sequence of operations proposed can be seen in those pictures:


Final drawing.



METAGRAF screen.



Text to be modified.



Rectangle created by clicking and dragging the mouse.



Line of text selected


To use this method is very simple and really quick. Nevertheless, sometimes it seems almost impossible to select just one object as there is another one very close to it. In those cases, the best thing is to group the close object with some other far away. Then the problem doesn't exist any more.

In short, for selecting objects there is always a quite simple way if the capabilities and way of using MG are well known. Anyway, the actual situation will not be the final one, as with implementation in full of the 3-D capabilities, there will be "true" layers corresponding to distance along the "Z" axis.

Now it will be explained in short which other buttons do we have to manipulate objects changing its default settings.


  • Clicking this button the small screen for selecting the kind of line to be used appears. It is needed to have an object already selected -as ususal- and it is possible to choose a different kind of lines, from plain ones to five other "models" acording to the size and separation of traits.

  • With this button a clone of the selected object will be created. Extremely useful for repeated objects it is one of the buttons that I use almost continually. It must be said that groups can also be cloned and this is something not possible in first distributions. It is not recommended for cloning the all new "geometrically-attached" objects, a new feature in this first version of the 1.2 series. Some of them, will not be cloned.
  • ,
    Those buttons serves for grouping and ungrouping the selected objects or groups. Very useful they simplify a lot some activities inside MG.

  • Button for giving any color wanted to points, lines, contours...etc. It is possible to come back always to the original color -black- just by selecting it and chossing black.
  • ,
    Those buttons are for filling and unfilling colors in closed objects. Now, its capabilities have been expanded so it is possible to fill with color non-closed objects, as polylines and bezier curves. The color will fill the open object supossing that the last line correspond to the join of the first and last point of the polyline. This capability is very interesting when doing "compound-objects", for example a rectangular base done with a polyline and a curved top done with a bezier, and everything filled with the same color.
    The second button unfills any filled selected object.

  • With this button it is possible to eliminate any selected object by clicking it once the object has been selected.

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