//{CodeReview:Triangulation}
EarClipper::EarClipper(const Polygon2D_t& polygon, const std::vector<const Polygon2D_t*>& innerPolygons)
{
   if (polygon.IsWellDefined())
   {
      FVector3 checkNormal = Vec3D::ZAxis();

      polygonWinding = polygon.GetWinding(checkNormal);

      for (std::size_t pointIndex = 0, numPoints = polygon.NumPoints(); pointIndex < numPoints; ++pointIndex)
      {
         vertices.push_back( Vertex(&polygon[pointIndex]) );
      }

      MakeSimple(innerPolygons, checkNormal);
   }
}
Example #2
0
    // Main function.
    // Process a set of blocks with specified entries, returns a shape
    // The Make* functions receive a NextEntries. If they fill it with data, those are the entries for the
    //   ->Next block on them, and the blocks are what remains in Blocks (which Make* modify). In this way
    //   we avoid recursing on Next (imagine a long chain of Simples, if we recursed we could blow the stack).
    Shape *Process(BlockSet &Blocks, BlockSet& InitialEntries, Shape *Prev) {
      PrintDebug("Process() called\n");
      BlockSet *Entries = &InitialEntries;
      BlockSet TempEntries[2];
      int CurrTempIndex = 0;
      BlockSet *NextEntries;
      Shape *Ret = NULL;
      #define Make(call) \
        Shape *Temp = call; \
        if (Prev) Prev->Next = Temp; \
        if (!Ret) Ret = Temp; \
        if (!NextEntries->size()) { PrintDebug("Process() returning\n"); return Ret; } \
        Prev = Temp; \
        Entries = NextEntries; \
        continue;
      while (1) {
        PrintDebug("Process() running\n");
        DebugDump(Blocks, "  blocks : ");
        DebugDump(*Entries, "  entries: ");

        CurrTempIndex = 1-CurrTempIndex;
        NextEntries = &TempEntries[CurrTempIndex];
        NextEntries->clear();

        if (Entries->size() == 0) return Ret;
        if (Entries->size() == 1) {
          Block *Curr = *(Entries->begin());
          if (Curr->BranchesIn.size() == 0) {
            // One entry, no looping ==> Simple
            Make(MakeSimple(Blocks, Curr, *NextEntries));
          }
          // One entry, looping ==> Loop
          Make(MakeLoop(Blocks, *Entries, *NextEntries));
        }
        // More than one entry, try to eliminate through a Multiple groups of
        // independent blocks from an entry/ies. It is important to remove through
        // multiples as opposed to looping since the former is more performant.
        BlockBlockSetMap IndependentGroups;
        FindIndependentGroups(Blocks, *Entries, IndependentGroups);

        PrintDebug("Independent groups: %d\n", IndependentGroups.size());

        if (IndependentGroups.size() > 0) {
          // We can handle a group in a multiple if its entry cannot be reached by another group.
          // Note that it might be reachable by itself - a loop. But that is fine, we will create
          // a loop inside the multiple block (which is the performant order to do it).
          for (BlockBlockSetMap::iterator iter = IndependentGroups.begin(); iter != IndependentGroups.end();) {
            Block *Entry = iter->first;
            BlockSet &Group = iter->second;
            BlockBlockSetMap::iterator curr = iter++; // iterate carefully, we may delete
            for (BlockBranchMap::iterator iterBranch = Entry->BranchesIn.begin(); iterBranch != Entry->BranchesIn.end(); iterBranch++) {
              Block *Origin = iterBranch->first;
              if (Group.find(Origin) == Group.end()) {
                // Reached from outside the group, so we cannot handle this
                PrintDebug("Cannot handle group with entry %d because of incoming branch from %d\n", Entry->Id, Origin->Id);
                IndependentGroups.erase(curr);
                break;
              }
            }
          }

          // As an optimization, if we have 2 independent groups, and one is a small dead end, we can handle only that dead end.
          // The other then becomes a Next - without nesting in the code and recursion in the analysis.
          // TODO: if the larger is the only dead end, handle that too
          // TODO: handle >2 groups
          // TODO: handle not just dead ends, but also that do not branch to the NextEntries. However, must be careful
          //       there since we create a Next, and that Next can prevent eliminating a break (since we no longer
          //       naturally reach the same place), which may necessitate a one-time loop, which makes the unnesting
          //       pointless.
          if (IndependentGroups.size() == 2) {
            // Find the smaller one
            BlockBlockSetMap::iterator iter = IndependentGroups.begin();
            Block *SmallEntry = iter->first;
            int SmallSize = iter->second.size();
            iter++;
            Block *LargeEntry = iter->first;
            int LargeSize = iter->second.size();
            if (SmallSize != LargeSize) { // ignore the case where they are identical - keep things symmetrical there
              if (SmallSize > LargeSize) {
                Block *Temp = SmallEntry;
                SmallEntry = LargeEntry;
                LargeEntry = Temp; // Note: we did not flip the Sizes too, they are now invalid. TODO: use the smaller size as a limit?
              }
              // Check if dead end
              bool DeadEnd = true;
              BlockSet &SmallGroup = IndependentGroups[SmallEntry];
              for (BlockSet::iterator iter = SmallGroup.begin(); iter != SmallGroup.end(); iter++) {
                Block *Curr = *iter;
                for (BlockBranchMap::iterator iter = Curr->BranchesOut.begin(); iter != Curr->BranchesOut.end(); iter++) {
                  Block *Target = iter->first;
                  if (SmallGroup.find(Target) == SmallGroup.end()) {
                    DeadEnd = false;
                    break;
                  }
                }
                if (!DeadEnd) break;
              }
              if (DeadEnd) {
                PrintDebug("Removing nesting by not handling large group because small group is dead end\n");
                IndependentGroups.erase(LargeEntry);
              }
            }
          }

          PrintDebug("Handleable independent groups: %d\n", IndependentGroups.size());

          if (IndependentGroups.size() > 0) {
            // Some groups removable ==> Multiple
            Make(MakeMultiple(Blocks, *Entries, IndependentGroups, Prev, *NextEntries));
          }
        }
        // No independent groups, must be loopable ==> Loop
        Make(MakeLoop(Blocks, *Entries, *NextEntries));
      }
    }