When drawing a Project with ArchiCAD, overlapping elements will be drawn according to a specified stacking order.
About Drawing Index
When using the Bring Forward/ Bring to Front/ Send Backward/ Send to Back commands, ArchiCAD uses an internal index for each element to determine an order they typically used in architectural drawings.
This piece of information is called Drawing Index. Each element type gets a default Drawing Index when it is placed on the Floor Plan. The minimum and maximum values of this index are 1 and 14, respectively.
The following table shows the default Drawing Index of different element types:
Elements can be arranged with the commands in Edit/ Display Order menu:
- Bring Froward: When an Element is Brought Forward, its Drawing Index is decreased by one. When the Element is completely in the front, its Drawing Index is 1. If you try to again Bring it Forward, ArchiCAD gives the following message: “Cannot bring some element(s) closer. Top stack level reached.”
- Send Backward: Similarly, when an Element is sent Backward, its Drawing Index is increased by one. When the Element is completely in the back, its Drawing Index is 14. If you try to again Send it Backward, ArchiCAD gives the following message: “Cannot send some element(s) farther. Bottom stack level reached.”
The Zone is a special case as it is composed of a Zone polygon and a Zone Stamp. As you can see from the above table, Zone Stamp is basically a Text, and is handled accordingly. The Zone polygon is a fill and is handled just like a Fill; they have the same Drawing Index. The order in which they are drawn is determined by the settings of the Display Options Dialog’s Zone Polygon field. If it is set to ‘Over the Fills’, as default, Fills are drawn first, so Zones will overlap Fills. If it is set to Under the Fills’, as default, Zone polygons are drawn first, so Fills will overlap Zones.
- Reset Default Order: This command restores the default overlapping order described previously.
How ArchiCAD determines which element to draw first and last
- Different priority: First, it draws Elements with the highest Drawing Index (furthermost to the bottom, everything overlaps it). From among Elements with the same Drawing Index, it draws Elements in order of their Priority hard-coded into ArchiCAD. Element types with higher Priority are drawn later, so they will overlap Elements with lower Priorities.
- Same priority: From Elements with the same Priority, the one earlier on the above list has higher Priority, so it is drawn later, thereby overlapping Elements later in the same line of the list. For example, a Spline has the same Priority as a Line, but comes earlier on the list. So as default a Spline will always overlap a Line (this of course can be changed by Send to Back/Bring to Front).
- Same priority, same element type: From Elements of the same type, the one created/modified later will overlap the other. For example, if a blue fill is drawn, then a green fill, the green fill will overlap the blue one. If then the blue fill is change to red, it will overlap the green fill, as this fill was last modified. When attributes of an element are transferred using ALT/OPT-click and CTRL-ALT/CMD-OPT-click, the Drawing Index of the Element is not transferred so overlapping order is not changed by this operation.
A Wall, a Fill and a Zone are drawn. They all overlap with each other.
The Wall is Sent Backwards. In this case, the Drawing index of the Wall, the Zone polygon and the Fill are all ‘9’.
The Drawing index of the Zone stamp is ‘5’. Let us say, Zone polygon is set to ‘Under the Fills’ in the Display Options Dialog. In this case, the Zone Polygon will be drawn first, then the Fill, then the Wall (because it has higher Priority than either Zones or Fills), and lastly the Zone Stamp.
This means the Zone stamp will be the topmost Element, and then comes the Wall, then the Fill, which is followed by the Zone polygon.