# -*- coding: utf-8 -*- """Cinema 4D Script Manager: select similar geometric polygon normals. Usage: select one or more faces on an editable polygon object in Polygon mode, then run the script. Capture the reference faces, set the tolerance, and apply. The non-modal floating window stays open; Restore retrieves the captured selection. After changing topology, capture the references again. Each face is compared with EVERY initially selected reference face (no propagation). Hidden faces are ignored. Ctrl+Z undoes the selection. Normals are calculated in object-local space, without Phong normals or deformations. N-gons use Cinema 4D's internal triangles and quads. Designed for Cinema 4D Python 3; tested locally by the author in Cinema 4D 2026. """ import math import c4d from c4d import gui DEFAULT_ANGLE = 5.0 IGNORE_OPPOSITE_NORMALS = False # True: accept parallel faces pointing in the opposite direction. def face_normal(points, polygon): """Unit normal (sum of both triangles for a quad).""" a, b, c, d = (points[i] for i in (polygon.a, polygon.b, polygon.c, polygon.d)) ab = (b.x - a.x, b.y - a.y, b.z - a.z) ac = (c.x - a.x, c.y - a.y, c.z - a.z) ad = (d.x - a.x, d.y - a.y, d.z - a.z) n = (ab[1]*ac[2] - ab[2]*ac[1] + ac[1]*ad[2] - ac[2]*ad[1], ab[2]*ac[0] - ab[0]*ac[2] + ac[2]*ad[0] - ac[0]*ad[2], ab[0]*ac[1] - ab[1]*ac[0] + ac[0]*ad[1] - ac[1]*ad[0]) length = math.sqrt(sum(v*v for v in n)) return tuple(v / length for v in n) if length > 0.0 else None def matches(normal, references, angle, ignore_opposite=False): if normal is None: return False threshold = math.cos(math.radians(angle)) for reference in references: dot = sum(a*b for a, b in zip(normal, reference)) if ignore_opposite: dot = abs(dot) if dot >= threshold - 1e-12: return True return False class SimilarDialog(gui.GeDialog): ANGLE, OPPOSITE, CAPTURE, APPLY, RESTORE, STATUS = range(1001, 1007) def __init__(self): super().__init__() self.obj = None self.source_doc = None self.seeds = set() self.topology = None def CreateLayout(self): self.SetTitle("Select Similar - Angle") self.GroupBegin(2000, c4d.BFH_SCALEFIT, 1, 0) self.GroupBorderSpace(12, 12, 12, 12) self.AddStaticText(2001, c4d.BFH_LEFT, name="1. Select reference faces in the viewport.") self.AddButton(self.CAPTURE, c4d.BFH_SCALEFIT, name="Capture reference selection") self.AddStaticText(2002, c4d.BFH_LEFT, name="2. Angle tolerance in degrees (0 to 180)") self.AddEditSlider(self.ANGLE, c4d.BFH_SCALEFIT) self.AddCheckbox(self.OPPOSITE, c4d.BFH_LEFT, 0, 0, "Include opposite normals") self.AddButton(self.APPLY, c4d.BFH_SCALEFIT, name="Apply selection") self.AddButton(self.RESTORE, c4d.BFH_SCALEFIT, name="Restore reference selection") self.AddStaticText(self.STATUS, c4d.BFH_SCALEFIT, name="No reference selection captured.") self.AddStaticText(2003, c4d.BFH_LEFT, name="Ctrl+Z: undo. After extruding: capture again.") self.GroupEnd() return True def InitValues(self): self.SetFloat(self.ANGLE, DEFAULT_ANGLE, min=0.0, max=180.0, step=0.1) self.SetBool(self.OPPOSITE, False) return True def status(self, text): self.SetString(self.STATUS, text) @staticmethod def signature(obj): return (obj.GetPointCount(), tuple((p.a, p.b, p.c, p.d) for p in obj.GetAllPolygons())) def capture(self): doc = c4d.documents.GetActiveDocument() obj = doc.GetActiveObject() if obj is None or not obj.CheckType(c4d.Opolygon): self.status("Choose an editable polygon object.") return if doc.GetMode() != c4d.Mpolygons: self.status("Switch to Polygon mode.") return sel, hidden = obj.GetPolygonS(), obj.GetPolygonH() seeds = {i for i in range(obj.GetPolygonCount()) if sel.IsSelected(i) and not hidden.IsSelected(i)} if not seeds: self.status("Select at least one visible face.") return self.obj, self.source_doc, self.seeds = obj, doc, seeds self.topology = self.signature(obj) self.status("{}: {} reference face(s).".format(obj.GetName(), len(seeds))) def validated_target(self): doc = c4d.documents.GetActiveDocument() try: if (self.obj is None or not self.obj.IsAlive() or doc != self.source_doc or self.obj.GetDocument() != doc or doc.GetActiveObject() != self.obj): self.status("Object/document changed: capture the references.") return None if doc.GetMode() != c4d.Mpolygons: self.status("Switch to Polygon mode.") return None if self.signature(self.obj) != self.topology: self.status("Topology changed: capture the references.") return None except ReferenceError: self.status("Object deleted: capture the references.") return None return doc, self.obj def apply_selection(self, restore=False): target = self.validated_target() if target is None: return doc, obj = target hidden, sel = obj.GetPolygonH(), obj.GetPolygonS() count = obj.GetPolygonCount() # Preserve the CURRENT selection state of hidden polygons. result = {i for i in range(count) if hidden.IsSelected(i) and sel.IsSelected(i)} visible_seeds = {i for i in self.seeds if not hidden.IsSelected(i)} result.update(visible_seeds) if not restore: angle = self.GetFloat(self.ANGLE) if not math.isfinite(angle) or not 0 <= angle <= 180: self.status("Invalid angle: use 0 to 180 degrees.") return if not visible_seeds: self.status("References hidden: capture visible faces.") return points = obj.GetAllPoints() normals = [face_normal(points, p) for p in obj.GetAllPolygons()] refs = list(dict.fromkeys(normals[i] for i in visible_seeds if normals[i] is not None)) if not refs: self.status("Zero-area references: choose other faces.") return result.update(i for i, n in enumerate(normals) if not hidden.IsSelected(i) and matches(n, refs, angle, self.GetBool(self.OPPOSITE))) current = {i for i in range(count) if sel.IsSelected(i)} if current != result: c4d.StopAllThreads() doc.StartUndo() try: doc.AddUndo(c4d.UNDOTYPE_CHANGE_SELECTION, obj) sel.DeselectAll() for i in result: sel.Select(i) obj.Message(c4d.MSG_UPDATE) finally: doc.EndUndo() c4d.EventAdd() self.status("{} visible face(s) selected.".format( sum(not hidden.IsSelected(i) for i in result))) def Command(self, control_id, msg): if control_id == self.CAPTURE: self.capture() elif control_id == self.APPLY: self.apply_selection() elif control_id == self.RESTORE: self.apply_selection(restore=True) return True # A global reference keeps the asynchronous window alive in Script Manager. _dialog = None def main(): global _dialog if _dialog is None: _dialog = SimilarDialog() _dialog.Open(c4d.DLG_TYPE_ASYNC, defaultw=440, defaulth=280) if __name__ == "__main__": main()