PolygonObject.GetPolygonTranslationMap()
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On 04/06/2013 at 21:59, xxxxxxxx wrote:
Hi,
has someone experience with PolygonObject.GetPolygonTranslationMap() ? The methods
output does not make any sense to me. I have used the search function which does come
up with a cpp code example, but that uses also PolygonObject->GetNGonTranslationMap()
which is not wrapped for python. For a linear polygon strip of 8 polygons with no ngons the
method returns :[0, 1, 2, 3, 4, 5, 6, 7]
If I do perform two melting operations to group the polygons in two ngons and one
polygon (0, 1, 2 - 3 - 4, 5, 6, 7) the method returns :[0, 0, 0]
I just need a method that allows me to retrieve the the polygons attached to a ngon.
I could write more, about what I suspect and what I have tried, but I guess that won't
help. So, thanks for your time and happy rendering,Ferdinand
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On 06/06/2013 at 05:03, xxxxxxxx wrote:
is something unclear about my question ?
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On 08/06/2013 at 04:56, xxxxxxxx wrote:
Hi littledevil,
I don't understand the return value of the method either. The explanation in the C++ documentation
is accurate, but it doesn't seem to be consistent with what the method returns. We either both do
not understand it correctly, or the implementation is buggy.
The returned list should have a length equal to the number of polygons in the polygon object, but
it isn't. If I create a Cube and check the output (without any N-Gons yet), the returned list is fine.
But after I add a point to an edge of the cube an create two ngons (resulting in 8 actual polygons),
the returned list does still contain only 6 elements.-Niklas
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On 08/06/2013 at 05:25, xxxxxxxx wrote:
Originally posted by xxxxxxxx
Hi littledevil,
I don't understand the return value of the method either. The explanation in the C++ documentation
is accurate, but it doesn't seem to be consistent with what the method returns. We either both do
not understand it correctly, or the implementation is buggy.The returned list should have a length equal to the number of polygons in the polygon object, but
it isn't. If I create a Cube and check the output (without any N-Gons yet), the returned list is fine.
But after I add a point to an edge of the cube an create two ngons (resulting in 8 actual polygons),
the returned list does still contain only 6 elements.-Niklas
Hey nikklas thanks for your answer,
The list size is actually shrinking with each ngon added the list size is always ngon count + count
of polygons not bound in a ngon. It would be great to get a official Maxon answer on that topic.Also wrapping _lib_ngon.h _and lib_modeling.h for python would be a great addition for future
python SDK versions, rather than something useless (at least useless from my point of
view) like the new snapping 'module' which is basically just pushing BaseContainer around,
which could also be done without that module.Happy rendering,
Ferdinand -
On 14/06/2013 at 11:40, xxxxxxxx wrote:
The problem remains unresolved for me , I would really appreciate an official statement
on the topic. -
On 26/04/2017 at 14:59, xxxxxxxx wrote:
I'm running into the same issue! When I count the number of NGons returned by GetPolygonTranslationMap() it's always fewer than the total number of polygons in my scene.
import c4d def main() : obj = op.GetObject() poly_to_ngons = obj.GetPolygonTranslationMap() ngons_to_polys = {} for poly_id, ngon_id in enumerate(poly_to_ngons) : ngon = ngons_to_polys.get(ngon_id, list()) ngons_to_polys[ngon_id] = ngon + [poly_id] # I expect this to be the same as the list of Ngons in the structure manager. # it isn't. print list(set(poly_to_ngons)) -
On 27/04/2017 at 01:28, xxxxxxxx wrote:
Hi,
unfortunately you are both right. GetPolygonTranslationMap() is broken in Python currently. The bug is filed and we are working on it. Sorry.
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On 27/04/2017 at 10:37, xxxxxxxx wrote:
Thanks for the heads up. I've put together a probably horribly inefficient algorithm that I think retrieves all n-gons and non-n-gons.
def GetAllNgons(obj) : """Returns a list of ngons & polygons. Its all n-gons as they first appear based on poly_id then edge order. Followed by all non-ngon polys in their poly order. Output will looks something like: [[0, 2, 3], [4, 6], [1], [5]] """ neighbor = c4d.utils.Neighbor() neighbor.Init(obj) polys = obj.GetAllPolygons() poly_count = len(polys) ngon_count = obj.GetNgonCount() ngon_edges_compact = obj.GetNgonEdgesCompact() # N-gon info for each polygon non_ngons = [] ngon_polys = [] ngons = None edges = [] # Get NGon Polygons for poly_id in xrange(poly_count) : edge_value = ngon_edges_compact[poly_id] # Bitmask w/ slots for each edge in a quad # No need to calculate n-gons if there aren't any if not edge_value: non_ngons.append([poly_id]) # Store it as a one item list to match format of ngons continue poly = polys[poly_id] poly_info = neighbor.GetPolyInfo(poly_id) for side in xrange(4) : # Skip the fourth "edge" of triangles. if side==2 and (poly.c == poly.d) : continue edge = None if side == 0: edge = (poly.a, poly.b) elif side == 1: edge = (poly.b, poly.c) elif side == 2: edge = (poly.c, poly.d) elif side == 3: edge = (poly.d, poly.a) # N-Gon Edge if not (edge_value & (1 << side) == 0) : if poly_id not in ngon_polys: ngon_polys.append(poly_id) # Get the neighborning hidden ngon poly, should be safe to assume there will always be one. adjacent_poly = neighbor.GetNeighbor(edge[0], edge[1], poly_id) if ngons is None: ngon = [poly_id, adjacent_poly] ngons = [ngon] else: # Add this polygon to an existing set if one exists present = False print "ngons: ", ngons for i, poly_set in enumerate(ngons) : print "poly_set: ", poly_set if adjacent_poly in poly_set: ngons[i] = ngons[i][:] + [poly_id] present = True if not present: ngons.append([poly_id, adjacent_poly]) for i, poly_set in enumerate(ngons) : ngons[i] = list(set(ngons[i])) ngons = ngons + non_ngons return ngons -
On 28/04/2017 at 03:42, xxxxxxxx wrote:
Interesting method Donovan.
But it appear to be slower than my method get_ngonv3
https://developers.maxon.net/forum/topic/9820#52347Here you have an ugly benchmarking with both version https://pastebin.com/3s8UbwDv
But your version don't need to have op in a doc.
Anyway thanks for sharing.
I guess the ngon class is really something missing in the python SDK.