You can dynamically change the roof slant angle by choosing Change Roof Pitch from the pet palette when editing a roof pitch in 3D window. Note that the hinge for the roof is the roof pivot line.
You can still use the old method of cropping the walls to a single roof, used mainly to trim walls in an angle. If you are working in ArchiCAD 18 or older you already know that you can right-click the wall and crop the wall. However, if you are in ArchiCAD 19 or a newer
You can use the 3D cutaway function to create a custom 3D cut plane in any direction Just turn on the 3D cutaway symbol and click the arrow to the right to select the Custom Plane option. Then hover the cursor to the element you want the cut plane to snap to.
When you rotate a view like explained in this old article: http://blog.cadimage.com/2012/10/rotate-orientation/ You may find that the marker head of the details placed in plan are rotating with the view. A simple way to allow the marker to rotate is to check the standard Detail Marker to rotate with the view checking this simple settings:
You may know about the Roof thickness is usually a parallel dimension related of the roof angle. However, if you want to enter the roof thickness as a vertical dimension, if the roof is a simple roof, you can open the settings and click the option to the right and assign the dimension to be
You can change the Roof Slant Units from degrees to percentage with the Pull-out menu to the right , within the Roof Selection Settings.
Setting a fixed angle in the Text default settings will ensure text remains at that angle regardless of drawing orientation. For example, setting the value to 0.000 will see the resulting text box remain horizontal. After orientation change . . .
To set the incremental angle of your Guide Lines, go to Options > Work Environment > Guide Lines and set the desired angle. If your project has no angled walls, you can set this to 90 so ArchiCAD automatically snaps to only horizontal and vertical.
Holding the Shift key when placing an element locks the direction, but you can also force hold a specific Angle or X or Y coordinate value. Hit Alt+A, Alt+X or Alt+Y whilst placing the element.