Merge branch 'dev' of https://github.com/topology-tool-kit/ttk into mtnn_refactor

Author: julien-tierny

ChangeLog.md

@@ -1,8 +1,9 @@
 ## TTK - ChangeLog
 =
 ### dev
-- Cycle-aware dimensionality reduction (TopoAE++)
+- Cycle-aware dimensionality reduction (TopoAE++, IEEE TVCG 2026)
 - Distributed computation of persistent homology! (IEEE TPDS 2025)
+- Discrete vector field topology! (IEEE VIS 2024)
 - New backend for TrackingFromFields (critical point based)
 - Fast planar Rips filtration persistence computation
 - Migration to ParaView 6

core/base/common/welcomeMsg.inl

@@ -2,7 +2,7 @@
 // Julien Tierny <[email protected]>
 // January 2020.
 
-// "TTK                   (c) 2025"
+// "TTK                   (c) 2026"
 
 printMsg(
   debug::output::BOLD
@@ -12,7 +12,7 @@ printMsg(
   debug::LineMode::NEW,
   stream);
 printMsg(debug::output::BOLD
-  + "|_   _|_   _| |/ /                   / /__\\ \\  |___ \\ / _ \\___ \\ / /"
+  + "|_   _|_   _| |/ /                   / /__\\ \\  |___ \\ / _ \\___ \\ / /_"
            + debug::output::ENDCOLOR,
          debug::Priority::PERFORMANCE,
          debug::LineMode::NEW,

core/base/discreteVectorField/CMakeLists.txt

@@ -0,0 +1,11 @@
+ttk_add_base_library(discreteVectorField
+  SOURCES
+    DiscreteVectorField.cpp
+  HEADERS
+    DiscreteVectorField.h
+    DiscreteVectorField_Template.h
+  DEPENDS
+    triangulation
+    surfaceGeometrySmoother
+    discreteGradient
+    )

core/base/discreteVectorField/DiscreteVectorField.cpp

@@ -0,0 +1,209 @@
+#include <DiscreteVectorField.h>
+
+using namespace std;
+using namespace ttk;
+using namespace dcvf;
+
+int DiscreteVectorField::getDimensionality() const {
+  return dimensionality_;
+}
+
+int DiscreteVectorField::getNumberOfDimensions() const {
+  return dimensionality_ + 1;
+}
+
+void DiscreteVectorField::initMemory(
+  const AbstractTriangulation &triangulation) {
+
+  Timer tm{};
+  const int numberOfDimensions = this->getNumberOfDimensions();
+
+  // init number of cells by dimension
+  std::vector<SimplexId> numberOfCells(numberOfDimensions);
+  for(int i = 0; i < numberOfDimensions; ++i) {
+    numberOfCells[i] = this->getNumberOfCells(i, triangulation);
+  }
+
+  // clear & init discrete vectors memory
+  for(int i = 0; i < dimensionality_; ++i) {
+    (*vectors_)[2 * i].clear();
+    (*vectors_)[2 * i].resize(numberOfCells[i], -1);
+    (*vectors_)[2 * i + 1].clear();
+    (*vectors_)[2 * i + 1].resize(numberOfCells[i + 1], -1);
+  }
+
+  std::vector<std::vector<std::string>> rows{
+    {"#Vertices", std::to_string(numberOfCells[0])},
+    {"#Edges", std::to_string(numberOfCells[1])},
+  };
+
+  if(dimensionality_ >= 2) {
+    rows.emplace_back(
+      std::vector<std::string>{"#Triangles", std::to_string(numberOfCells[2])});
+  }
+
+  if(dimensionality_ == 3) {
+    rows.emplace_back(
+      std::vector<std::string>{"#Tetras", std::to_string(numberOfCells[3])});
+  }
+
+  this->printMsg(rows);
+  this->printMsg("Initialized discrete vectors memory", 1.0,
+                 tm.getElapsedTime(), this->threadNumber_);
+}
+
+std::pair<size_t, SimplexId>
+  DiscreteVectorField::numUnpairedFaces(const CellOutExt &c,
+                                        const outwardStarType &ls) const {
+  // c.dim_ cannot be <= 1
+  if(c.dim_ == 2) {
+    return numUnpairedFacesTriangle(c, ls);
+  } else if(c.dim_ == 3) {
+    return numUnpairedFacesTetra(c, ls);
+  }
+
+  return {0, -1};
+}
+
+std::pair<size_t, SimplexId> DiscreteVectorField::numUnpairedFacesTriangle(
+  const CellOutExt &c, const outwardStarType &ls) const {
+  // number of unpaired faces
+  std::pair<size_t, SimplexId> res{0, -1};
+
+  // loop over edge faces of triangle
+  // (2 edges per triangle in outward star)
+  for(size_t i = 0; i < 2; ++i) {
+    if(!ls[1][c.faces_[i]].paired_) {
+      res.first++;
+      res.second = c.faces_[i];
+    }
+  }
+
+  return res;
+}
+
+std::pair<size_t, SimplexId>
+  DiscreteVectorField::numUnpairedFacesTetra(const CellOutExt &c,
+                                             const outwardStarType &ls) const {
+  // number of unpaired faces
+  std::pair<size_t, SimplexId> res{0, -1};
+
+  // loop over triangle faces of tetra
+  for(const auto f : c.faces_) {
+    if(!ls[2][f].paired_) {
+      res.first++;
+      res.second = f;
+    }
+  }
+
+  return res;
+}
+
+bool DiscreteVectorField::isCellCritical(const int cellDim,
+                                         const SimplexId cellId) const {
+
+  if(cellDim > this->dimensionality_) {
+    return false;
+  }
+#ifndef TTK_ENABLE_KAMIKAZE
+  if(cellId < 0) {
+    this->printErr("Invalid cell ID given to isCellCritical");
+    return false;
+  }
+#endif
+
+  if(cellDim == 0) {
+    return ((*vectors_)[0][cellId] == NULL_CONNECTION);
+  }
+
+  if(cellDim == 1) {
+    return (
+      (*vectors_)[1][cellId] == NULL_CONNECTION
+      && (dimensionality_ == 1 || (*vectors_)[2][cellId] == NULL_CONNECTION));
+  }
+
+  if(cellDim == 2) {
+    return (
+      (*vectors_)[3][cellId] == NULL_CONNECTION
+      && (dimensionality_ == 2 || (*vectors_)[4][cellId] == NULL_CONNECTION));
+  }
+
+  if(cellDim == 3) {
+    return ((*vectors_)[5][cellId] == NULL_CONNECTION);
+  }
+
+  return false;
+}
+
+bool DiscreteVectorField::isCellCritical(const Cell &cell) const {
+  return isCellCritical(cell.dim_, cell.id_);
+}
+
+int DiscreteVectorField::setManifoldSize(
+  const std::array<std::vector<SimplexId>, 4> &criticalCellsByDim,
+  const SimplexId *const ascendingManifold,
+  const SimplexId *const descendingManifold,
+  std::vector<SimplexId> &manifoldSize) const {
+
+  const auto nCritPoints{
+    criticalCellsByDim[0].size() + criticalCellsByDim[1].size()
+    + criticalCellsByDim[2].size() + criticalCellsByDim[3].size()};
+
+  const auto dim{this->dimensionality_};
+
+  if(nCritPoints == 0
+     || (criticalCellsByDim[0].empty() && criticalCellsByDim[dim].empty())) {
+    // no critical points || no extrema
+    return 0;
+  }
+
+  manifoldSize.resize(nCritPoints, 0);
+
+  // descending manifold cells size
+  if(!criticalCellsByDim[0].empty()) {
+    const SimplexId nMin = static_cast<SimplexId>(criticalCellsByDim[0].size());
+    for(SimplexId i = 0; i < numberOfVertices_; ++i) {
+      if(descendingManifold[i] != -1 && descendingManifold[i] < nMin) {
+        manifoldSize[descendingManifold[i]]++;
+      }
+    }
+  }
+
+  if(!criticalCellsByDim[dim].empty()) {
+    // index of first maximum in critical points array
+    const auto nFirstMaximum{nCritPoints - criticalCellsByDim[dim].size()};
+    const SimplexId nMax
+      = static_cast<SimplexId>(criticalCellsByDim[dim].size());
+    // ascending manifold cells size
+    for(SimplexId i = 0; i < numberOfVertices_; ++i) {
+      if(ascendingManifold[i] != -1 && ascendingManifold[i] < nMax) {
+        manifoldSize[ascendingManifold[i] + nFirstMaximum]++;
+      }
+    }
+  }
+
+  return 0;
+}
+
+#ifdef TTK_ENABLE_MPI
+void DiscreteVectorField::setCellToGhost(const int cellDim,
+                                         const SimplexId cellId) {
+  if(cellDim == 0) {
+    (*vectors_)[0][cellId] = GHOST_CONNECTION;
+  }
+
+  if(cellDim == 1) {
+    (*vectors_)[1][cellId] = GHOST_CONNECTION;
+    (*vectors_)[2][cellId] = GHOST_CONNECTION;
+  }
+
+  if(cellDim == 2) {
+    (*vectors_)[3][cellId] = GHOST_CONNECTION;
+    (*vectors_)[4][cellId] = GHOST_CONNECTION;
+  }
+
+  if(cellDim == 3) {
+    (*vectors_)[5][cellId] = GHOST_CONNECTION;
+  }
+}
+#endif