surface slope arrows

Wot, not poss even with a TIN surface?

I thought I saw something about raindrop on surface this is the slope arrow. TINWATERDROP ?

Yes CIV3D has a arrow on every triangle built in option. I guess could look at triangles and have a formula based on the 3 XYZ for maximum slope.

find maximum slop in 3d face

How is this computed, I tried from the normal of the triangle, but it looks wrong

import traceback
from pyrx_imp import Rx, Ge, Gi, Db, Ap, Ed, Cv

print("added command tinoverruleon")
print("added command tinoverruleoff")


def OnPyUnloadApp() -> None:
    tinoverruleoff()


def centroid(tri):
    CX1 = (tri[0].x + tri[1].x + tri[2].x) / 3
    CX2 = (tri[0].y + tri[1].y + tri[2].y) / 3
    CX3 = (tri[0].z + tri[1].z + tri[2].z) / 3
    return Ge.Point3d(CX1, CX2, CX3)


class TinDrawOverrule(Gi.DrawableOverrule):
    def __init__(self):
        Gi.DrawableOverrule.__init__(self)

    def isApplicable(self, subject: Rx.RxObject) -> bool:
        return True

    def worldDraw(self, subject, wd) -> bool:
        try:
            flag = self.baseWorldDraw(subject, wd)
            tin = Cv.CvDbTinSurface.cast(subject)
            geo: Gi.Geometry = wd.geometry()
            traits = wd.subEntityTraits()
            traits.setColor(1)

            for tri in tin.triangles(True):
                cen = centroid(tri)
                u: Ge.Vector3d = (tri[1] - tri[0]).normalize()
                v: Ge.Vector3d = (tri[2] - tri[0]).normalize()
                n = u.crossProduct(v)
                d = n + Ge.Vector3d.kZAxis
                s = cen + (d * 6)
                e = cen - (d * 6)
                geo.polyline([s, e], n)

        except Exception as err:
            traceback.print_exception(err)
        finally:
            return flag


overrule = TinDrawOverrule()
desc = Cv.CvDbTinSurface.desc()


@Ap.Command("tinoverruleon")
def tinoverruleon():
    try:
        overrule.addOverrule(desc, overrule)
        overrule.setIsOverruling(True)

    except Exception as err:
        traceback.print_exception(err)


@Ap.Command("tinoverruleoff")
def tinoverruleoff():
    try:

        if overrule.removeOverrule(desc, overrule) == Db.ErrorStatus.eOk:
            overrule.setIsOverruling(False)
    except Exception as err:
        traceback.print_exception(err)

“Note: if you want to know the actual angle of slope, then you need to do some trigonometry”

I had that part right, getting the slope is weird. I’m getting old. This is pretty close

@Hela Have you tried _addSurfaceLabels in combination with CivilExplorer settings? It should behave as a dynamic label similar to C3D. That's at least how I use it for small projects.

@Tom Foster Correct, only works with TIN objects, no other object types

No, an arrow made of three Lines and a number made of TEXt, copied, oriented and edited many times, having determined each slope geometrically and read its angle in Properties!

Uh yes! Of course, once made, copied many, oriented and text-edited.