Geometry vertices from custom entity

[schoeller]

Dear all,

browsing the docs for BRX/.NET, the civil STRING entities unfortunately do not seem supported.
When trying to access the geometry from a string I do as follows:

        db = Db.curDb()
        ps, id, _ = Ed.Editor.entSel("\nSelect entities: ")

        ent = Db.Entity(id)
        pl = Db.Polyline3d.cast(Db.Entity(id))

The approach does not work. Is there any chance I may fetch the vertices from the string object otherwise?

Hints appreciated

Best

Seb

[CEXT-Dan]

Can you post a dwg with the entity?

[schoeller]

thanks for taking the time. Please find a dwg with sample objects attached.

strings.zip

[CEXT-Dan]

Turns out the entity is derived from AcDbCurve, so you can extract out the AcGeCurve. In this case it’s a AcGeCompositeCurve3d

@Ap.Command()
def doit0():
    try:
        db = Db.curDb()
        ps, id, _ = Ed.Editor.entSel("\nSelect: ", Db.Curve.desc())
        if ps != Ed.PromptStatus.eOk:
            raise RuntimeError("Yeet! {}: ".format(ps))
        string_points = []
        dbc = Db.Curve(id)
        gec = dbc.getAcGeCurve()
        if gec.type() == Ge.EntityId.kCompositeCrv3d:
            composite_curve = Ge.CompositeCurve3d.cast(gec)
            for curve_segment in composite_curve.getCurveList():
                if curve_segment.type() != Ge.EntityId.kLineSeg3d:
                    continue
                line_segment = Ge.LineSeg3d.cast(curve_segment)
                string_points.append(line_segment.startPoint())
            string_points.append(composite_curve.getEndPoint())  
        print(string_points)
    except Exception:
        traceback.print_exc()

[CEXT-Dan]

I did not see Bsyscvdbstringline in BRX, but I only did a quick search in the v26 header, AcDbCurve - > CivilDbCurve-> Bsyscvdbstringline. It explodes into a 3d polyline

[schoeller]

Absolovely!

[schoeller]

Found entities where offset does not work. len(string_points)=5, len(pts)=5 and try_offset_p3d(pl3, 0) is empty.

import traceback
from pyrx import Ap, Db, Ed, Ge


def try_offset_p3d(polyline_3d: Db.Polyline3d, offset_distance: float):
    offset_points = []

    # Convert the database polyline to a geometric curve for calculations
    ge_curve = polyline_3d.getAcGeCurve()

    # Calculate the offset curves
    offset_curves = ge_curve.getTrimmedOffset(
        offset_distance, Ge.Vector3d.kZAxis, Ge.OffsetCrvExtType.kExtend
    )

    for offset_curve in offset_curves:
        # We only process composite curves (curves made of multiple segments)
        if offset_curve.type() != Ge.EntityId.kCompositeCrv3d:
            continue

        composite_curve = Ge.CompositeCurve3d.cast(offset_curve)

        # Iterate through the individual segments of the composite curve
        for curve_segment in composite_curve.getCurveList():
            # We only care about linear segments for this specific logic
            if curve_segment.type() != Ge.EntityId.kLineSeg3d:
                continue

            line_segment = Ge.LineSeg3d.cast(curve_segment)

            # Add the start point of each segment to the list
            offset_points.append(line_segment.startPoint())

        # Add the very last point of the composite curve
        offset_points.append(composite_curve.getEndPoint())

    return offset_points


@Ap.Command()
def doit1():
    try:
        db = Db.curDb()
        ps, id, _ = Ed.Editor.entSel("\nSelect Curve/String: ", Db.Curve.desc())
        if ps != Ed.PromptStatus.eOk:
            raise RuntimeError("Yeet! {}: ".format(ps))

        string_points = []
        dbc = Db.Curve(id)
        gec = dbc.getAcGeCurve()
        if gec.type() == Ge.EntityId.kCompositeCrv3d:
            composite_curve = Ge.CompositeCurve3d.cast(gec)
            for curve_segment in composite_curve.getCurveList():
                if curve_segment.type() != Ge.EntityId.kLineSeg3d:
                    continue
                line_segment = Ge.LineSeg3d.cast(curve_segment)
                string_points.append(line_segment.startPoint())
            string_points.append(composite_curve.getEndPoint())
        print(len(string_points))

        pl3 = Db.Polyline3d(Db.Poly3dType.k3dSimplePoly, string_points, False)
        pts = pl3.getStretchPoints()
        print(len(pts))
        print(try_offset_p3d(pl3, 0))

    except Exception:
        traceback.print_exc()

strings1.zip

[CEXT-Dan]

That entity is not planar, which is a requirement for built-in offset functions to work. Another condition is that getTrimmedOffset must be passed the normal to the plane.
You can simulate OFFSET3D, I.e. do the offset in XY plane then reapply the Z

import traceback
from pyrx import Ap, Db, Ed, Ge


def get_3dpoly_points(pl: Db.Polyline3d):
    pts = []
    for vid in pl.vertexIds():
        v = Db.Polyline3dVertex(vid)
        pts.append(v.position())
    return pts


def interpolate_z(p2d, pts3d):
    """
    crude nearest-segment Z interpolation
    """
    best = None
    bestd = 1e99

    for i in range(len(pts3d) - 1):
        a = pts3d[i]
        b = pts3d[i + 1]

        midx = (a.x + b.x) * 0.5
        midy = (a.y + b.y) * 0.5

        d = (p2d.x - midx) ** 2 + (p2d.y - midy) ** 2
        if d < bestd:
            bestd = d
            best = (a.z + b.z) * 0.5

    return best if best is not None else 0.0


def rebuild_3dpoly_points(points2d, original3d):
    pnts = []
    for p in points2d:
        z = interpolate_z(p, original3d)
        pnts.append(Ge.Point3d(p.x, p.y, z))
    return pnts

#similar to OFFSET3D
@Ap.Command("OFF3DPOLY")
def offset_3dpoly():
    try:

        db = Db.curDb()

        ps, id, _ = Ed.Editor.entSel("\nSelect 3D polyline: ", Db.Polyline3d.desc())
        if ps != Ed.PromptStatus.eOk:
            return

        ps, offset = Ed.Editor.getReal("\nOffset distance: ")
        if ps != Ed.PromptStatus.eOk:
            return

        pl3d = Db.Polyline3d(id)
        pts3d = get_3dpoly_points(pl3d)

        # build temporary 2D polyline
        pl2d = Db.Polyline(pts3d)
        arr = pl2d.getOffsetCurves(offset)
        if len(arr) == 0:
            print("Offset failed")
            return

        # get the points from the offset
        pts2d = Db.Polyline.cast(arr[0]).toPoint2dList()
        pts3d = rebuild_3dpoly_points(pts2d, pts3d)

        db.addToModelspace(Db.Polyline3d(Db.Poly3dType.k3dSimplePoly, pts3d, False))
        print("Offset created")

    except Exception:
        traceback.print_exc()