great idea Cyril 
, think it could work
slope.dyn (6.7 KB)
You can calculate the slope of face geometry by using the FaceNormal and projecting onto the XY plane. You also now have the face geometry which could be used to intersect with other elements
EDIT: Z could be negative so testing for Z == 0 first instead of Z > 0
import clr
clr.AddReference("RevitAPI")
from Autodesk.Revit.DB import HostObjectUtils, UV
def face_slopes(floor):
result = []
for face in HostObjectUtils.GetTopFaces(floor):
normal = floor.GetGeometryObjectFromReference(face).FaceNormal
if normal.Z == 0: # Slope is 1, avoids div by zero
result.append(1)
else:
# Map normal onto xy plane
# No need to negate the normal as we are only using the length
result.append(
round(UV(normal.X / normal.Z, normal.Y / normal.Z).GetLength(), 4)
)
return result
output = []
floors = UnwrapElement(IN[0]) if isinstance(IN[0], list) else [UnwrapElement(IN[0])]
for floor in floors:
output.append(face_slopes(floor))
OUT = output
Great one Mike very usefull, if user want all surface slopes and not only from dimension…