@@ -3,7 +3,7 @@ %% %% Functions for reading and writing Wavefront ASCII files (.obj). %% -%% Copyright (c) 2001-2008 Bjorn Gustavsson +%% Copyright (c) 2001-2009 Bjorn Gustavsson %% %% See the file "license.terms" for information on usage and redistribution %% of this file, and for a DISCLAIMER OF ALL WARRANTIES. @@ -637,17 +637,57 @@ export_smooth_groups(#e3d_mesh{fs=Fs0,he=He0}) -> Cs = digraph_utils:components(G), digraph:delete(G), + %% Generate a mapping from Face to a list of all neighboring faces. + Neib0 = sofs:range(Fam0), + Neib1 = sofs:canonical_relation(Neib0), + Neib2 = sofs:relation_to_family(Neib1), + Neib3 = sofs:family_union(Neib2), + Neib4 = sofs:to_external(Neib3), + Neib = array:from_orddict(Neib4), + %% Number the smoothing groups starting from 1. + %% + %% Try to generate as few smoothing groups as possible, + %% since some applications may have trouble handling + %% hundreds or thousands of smoothing groups. + %% %% Return [{SG,#e3d_face{}}]. Fs = sofs:relation(Fs1, [{face,data}]), - Sg0 = number(Cs, 1, []), - Sg1 = sofs:relation(Sg0, [{group,[face]}]), - Sg2 = sofs:family_to_relation(Sg1), - Sg3 = sofs:converse(Sg2), - Sg4 = sofs:relative_product({Sg3,Fs}), - Sg = sofs:range(Sg4), + Sg0 = exp_sgs_1(Cs, Neib, array:new()), + Sg1 = sofs:relation(Sg0, [{face,group}]), + Sg2 = sofs:relative_product({Sg1,Fs}), + Sg = sofs:range(Sg2), sofs:to_external(Sg). +%% Return [{Face,SG}]. +exp_sgs_1([Fs|Cs], Neib, SgMap0) -> + SG = find_sg(Fs, Neib, SgMap0), + SgMap = foldl(fun(F, M) -> + array:set(F, SG, M) + end, SgMap0, Fs), + exp_sgs_1(Cs, Neib, SgMap); +exp_sgs_1([], _, SgMap) -> array:to_orddict(SgMap). + +%% find_sg(Faces, NeighborMap, SgMap) -> SG +%% Find the lowest smoothing group number (>= 1) that is not +%% used by any face that is a neighbor to any face in Faces. +%% +find_sg(Fs, Neib, SgMap) -> + find_sg_2(find_sg_1(Fs, Neib, SgMap, gb_sets:new()), 1). + +find_sg_1([F|Fs], Neib, SgMap, Acc0) -> + Acc = foldl(fun(N, A) -> + case array:get(N, SgMap) of + undefined -> A; + SG when is_integer(SG) -> gb_sets:add(SG, A) + end + end, Acc0, array:get(F, Neib)), + find_sg_1(Fs, Neib, SgMap, Acc); +find_sg_1([], _, _, Acc) -> gb_sets:to_list(Acc). + +find_sg_2([SG|T], SG) -> find_sg_2(T, SG+1); +find_sg_2(_, SG) -> SG. + build_edges(Fs) -> build_edges(Fs, []). e3d/e3d_obj.erl 1eccc5f27a05e538b92650f1975b82298c7aa34f Bjorn Gustavsson bjorng@users.sourceforge.net http://github.com/bjorng/wings/commit/091721dee22478956e3add58cf6637e9f3f06f17 091721dee22478956e3add58cf6637e9f3f06f17 2009-06-24T03:32:28-07:00 2009-06-24T03:32:28-07:00 OBJ export: Minimize the number of smoothing groups Some programs seems to have trouble coping with hundreds or thousands of smoothing groups, so we must limit the number of smoothing groups. NOTE: The Wavefront (OBJ) exporter now tries to minimize the number of smoothing groups. (Thanks to Ran13.) [bjorng] 094e4dafebc95b82ba3ffb14ce795af7caf9396b Bjorn Gustavsson bjorng@users.sourceforge.net