Creating, Selecting, and Editing Objects in GoPhast

There are five types of objects in GoPhast.  These are:

Points,
 Polylines,
 Polygons,
 Straight-Line objects, and
 Rectangles.

Each object consists of one or more vertices and has properties associated with it.  The properties of an object determine how it is used to specify spatial properties of the model.  Each object is associated with one of the three views of the model (top, front, or side).

Creating Objects

Objects are created by drawing them on the top, front or side views of the model.  The following sections describe how to create each type of object.

Points

Point objects have only a single vertex.  To create a point object, the user does the following.  (1) The user either selects Object|Create Point or clicks on the point button.  (2) The user moves the cursor to the location on one of the views of the model where a point object is desired.  (3) The user clicks the mouse button.  A point object will be created at the cursor location.  The Object Properties dialog box (See p. 48) will appear.  The Object Properties dialog box is used to specify the properties of the object.

Typical uses for point objects would be to define the elevations of the tops or bottoms of geologic units, point values for hydraulic properties that will be defined using interpolation, or well boundary conditions.

Polylines

Polyline objects have two or more vertices.  To create a polyline object, the user does the following.  (1) The user either selects Object|Create Line or clicks on the polyline button.  (2) The user moves the cursor to the location on one of the views of the model where the first vertex of the polyline object is desired.  (3) The user clicks the mouse button.  The first vertex of the polyline object will be created at the cursor location.  (4) To create additional vertices, the user continues clicking on the same view of the model.  (5) When all the desired vertices have been created, the user double-clicks at the last vertex or depresses the “Enter” key on the keyboard to complete the polyline.  As with points, the Object Properties dialog box (See p. 48) will be used to specify the properties of the object.

Typical uses for polylines are to define linear features such as rivers and boundary conditions located at the edge of the model.

Polygons

Polygon objects have four or more vertices.  The last vertex is always at the same location as the first vertex so a polygon with four vertices is a triangle.  To create a polygon object, the user does the following.  (1) The user either selects Object|Create Polygon or clicks on the polygon button.  (2) The user continues adding vertices as described with Polylines.  (3) When the polygon is complete, a final vertex will be added at the location of the first vertex to close the polygon.  As with points, the Object Properties dialog box (See p. 48) will be used to specify the properties of the object.

Typical uses for polygons are to define zones with differing media properties.

Straight-Lines

Straight-line objects are a special case of polylines in which all the line segments in the polyline are parallel with one of the edges of the grid.  To create a Straight-line object, the user does the following.  (1) The user either selects Object|Create Straight Line or clicks on the Straight-line button.  (2) The user continues adding vertices as described with Polylines.  As with points, the Object Properties dialog box (See p. 48) will be used to specify the properties of the object.

Typical uses of straight-line objects are the same as for polylines.

Rectangles

Rectangles are a special case of polygons that have four edges that are parallel to the grid.  To create a rectangle, the user does the following. (1)  The user either selects Object|Create Rectangle or clicks on the rectangle button.  (2) The user moves the cursor to the location on one of the views of the model where the first vertex of the rectangle object is desired.  (3) The user clicks the mouse button again at the opposite corner of the rectangle. As with points, the Object Properties dialog box (See p. 48) will be used to specify the properties of the object.

Typical uses of rectangle objects are the same as for polygons.

Selecting Objects

To edit, move, or delete and object, the object must first be selected.  Selected objects can be distinguished from objects that are not selected because the line used to draw the selected object is thicker and the vertices of the selected object are drawn as squares.  However, point objects are also drawn as squares even if they are not selected.  Selected point objects are drawn as solid squares whereas point objects that are not selected are drawn as hollow squares.  The object in figure 21A is selected; the object in figure 21B is not.  The object in figure 21C has one of its vertices selected.

selected object
non-selected object
an object with a selected vertex
A
B
C
Figure 21. Appearance of (A) selected object (B) non-selected object and (C) an object with a selected vertex.

There are several ways to select objects.  The easiest is to click on the Select objects button  and then click on the object.  Another way is instead of clicking on an object, click down somewhere on one view of the model that is not on any object and then drag the mouse button.  A rectangle will be drawn starting where the mouse was clicked down.  When the mouse button is released, any objects that are entirely within the rectangle will be selected.  Another option is to click on the Lasso button .  Then the user clicks down on one view of the model and moves the mouse.  A line will follow the mouse.  When the user releases the mouse, any objects that are entirely within the line will be selected.  

Usually, selecting one object causes any object that was already selected to be deselected.  However, if the Shift key is held down while selecting an object, then the objects that would normally be selected are toggled between selected and deselected and other objects remain selected.  

The Ctrl key also modifies how selection occurs when the Select objects  button is down but not when the Lasso  button is down.  The user can use the Ctrl key to select objects beneath another object.  If several objects are on top of one another, the user can click on the objects with the Ctrl key down and if none of the objects is selected, the uppermost one will be selected.  If the user clicks again with the Ctrl key down, the top object will be deselected and the next one down will be selected.  If the user clicks again with the Ctrl key down, the object below that will be selected.  The Shift and Ctrl key can be combined.

Individual vertices of an object can be selected as well as whole objects.  To select individual vertices, the user first selects an object and then clicks on the Select vertices button .  Next, the user clicks on the vertex he or she wishes to select.  To select additional vertices, the user clicks on them while holding down the Shift key. Vertices can only be selected on objects that are selected.  The user can also click down away from any vertices of a selected object, drag the mouse and release it to select vertices that are inside the rectangle defined by the locations where the user clicked down with the mouse button and where the user released it.  All the vertices outside the rectangle will be deselected (unless the Shift key is down).  If the user holds down the Shift key while clicking on a vertex, it will be toggled from selected to deselected or the reverse.

A number of dialog boxes allow the user to select objects.  See “Search for Objects Dialog Box” on p. 56, “Show or Hide Objects Dialog Box” on p. 56, “Select Objects by Name Dialog Box” on p. 58, and “Changing the Magnification” on p. 59.

Editing Objects

There are a number of ways to edit objects.  Objects can be deleted or moved.  Individual vertices in objects can be inserted, moved or deleted.  Edges of objects can be deleted.  The order of the objects can be changed.  Finally, the properties of objects can be changed.

To delete an object, select it and press the delete key on the keyboard.  To delete individual vertices, select the vertices and press the delete key.  One way to move objects or vertices is to select them, hold down the mouse button with the mouse curser on or inside the object, and move the mouse before releasing the mouse button.  Another way to move an object or individual vertices is to double click on the object.  Then on the tab labeled Vertices, type in new values for the coordinates of the vertices.  

To insert a vertex, first click on the Insert vertex button .  Then click on the edge of an object to insert a vertex at the position where the mouse was clicked.  If any object is selected, this procedure will only insert a vertex in the selected object.  If no object is selected, this procedure will insert a vertex into whichever object on which the user clicks.  To delete an edge of an object, click on the Delete segment button .  Then click on an edge of an object to delete that edge.  If deleting an edge will split the object into two separate pieces, one of the pieces will be a new object with the same properties as the original object except for its name.  

To change the order of objects, select one or more objects and right click on them.  Select one of the options in the pop-up menu to change the order of the objects.  It is also possible to select Object|Rearrange Objects…  The Rearrange Objects dialog box (p. 48) will appear.  In it, the user can drag objects to new positions.  

To edit the properties of one or more objects, select them and then double-click on one of them.  The Object Properties dialog box (p. 48) will appear in which the properties can be edited.  The user can also display the Object Properties dialog box to edit the properties of a single object by displaying the “Show or Hide Objects Dialog Box” (p. 56) and double-clicking on the name of the object.