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blender-5.2.0/extern/mantaflow/preprocessed/multigrid.h

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+
+
+// DO NOT EDIT !
+// This file is generated using the MantaFlow preprocessor (prep generate).
+
+/******************************************************************************
+ *
+ * MantaFlow fluid solver framework
+ * Copyright 2011 Tobias Pfaff, Nils Thuerey
+ *
+ * This program is free software, distributed under the terms of the
+ * Apache License, Version 2.0
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Multigrid solver by Florian Ferstl (florian.ferstl.ff@gmail.com)
+ *
+ * This is an implementation of the solver developed by Dick et al. [1]
+ * without topology awareness (= vertex duplication on coarser levels). This
+ * simplification allows us to use regular grids for all levels of the multigrid
+ * hierarchy and works well for moderately complex domains.
+ *
+ * [1] Solving the Fluid Pressure Poisson Equation Using Multigrid-Evaluation
+ *     and Improvements, C. Dick, M. Rogowsky, R. Westermann, IEEE TVCG 2015
+ *
+ ******************************************************************************/
+
+#ifndef _MULTIGRID_H
+#define _MULTIGRID_H
+
+#include "vectorbase.h"
+#include "grid.h"
+
+namespace Manta {
+
+//! Multigrid solver
+class GridMg {
+ public:
+  //! constructor: preallocates most of required memory for multigrid hierarchy
+  GridMg(const Vec3i &gridSize);
+  ~GridMg(){};
+
+  //! update system matrix A from symmetric 7-point stencil
+  void setA(const Grid<Real> *pA0,
+            const Grid<Real> *pAi,
+            const Grid<Real> *pAj,
+            const Grid<Real> *pAk);
+
+  //! set right-hand side after setting A
+  void setRhs(const Grid<Real> &rhs);
+
+  bool isASet() const
+  {
+    return mIsASet;
+  }
+  bool isRhsSet() const
+  {
+    return mIsRhsSet;
+  }
+
+  //! perform VCycle iteration
+  // - if src is null, then a zero vector is used instead
+  // - returns norm of residual after VCylcle
+  Real doVCycle(Grid<Real> &dst, const Grid<Real> *src = nullptr);
+
+  // access
+  void setCoarsestLevelAccuracy(Real accuracy)
+  {
+    mCoarsestLevelAccuracy = accuracy;
+  }
+  Real getCoarsestLevelAccuracy() const
+  {
+    return mCoarsestLevelAccuracy;
+  }
+  void setSmoothing(int numPreSmooth, int numPostSmooth)
+  {
+    mNumPreSmooth = numPreSmooth;
+    mNumPostSmooth = numPostSmooth;
+  }
+  int getNumPreSmooth() const
+  {
+    return mNumPreSmooth;
+  }
+  int getNumPostSmooth() const
+  {
+    return mNumPostSmooth;
+  }
+
+  //! Set factor for automated downscaling of trivial equations:
+  // 1*x_i = b_i  --->  trivialEquationScale*x_i = trivialEquationScale*b_i
+  // Factor should be significantly smaller than the scale of the entries in A.
+  //     Info: Trivial equations of the form x_i = b_i can have a negative
+  //     effect on the coarse grid operators of the multigrid hierarchy (due
+  //     to scaling mismatches), which can lead to slow multigrid convergence.
+  //     To avoid this, the solver checks for such equations when updating A
+  //     (and rhs) and scales these equations by a fixed factor < 1.
+  void setTrivialEquationScale(Real scale)
+  {
+    mTrivialEquationScale = scale;
+  }
+
+ private:
+  Vec3i vecIdx(int v, int l) const
+  {
+    return Vec3i(v % mSize[l].x,
+                 (v % (mSize[l].x * mSize[l].y)) / mSize[l].x,
+                 v / (mSize[l].x * mSize[l].y));
+  }
+  int linIdx(Vec3i V, int l) const
+  {
+    return V.x + V.y * mPitch[l].y + V.z * mPitch[l].z;
+  }
+  bool inGrid(Vec3i V, int l) const
+  {
+    return V.x >= 0 && V.y >= 0 && V.z >= 0 && V.x < mSize[l].x && V.y < mSize[l].y &&
+           V.z < mSize[l].z;
+  }
+
+  void analyzeStencil(int v, bool is3D, bool &isStencilSumNonZero, bool &isEquationTrivial) const;
+
+  void genCoarseGrid(int l);
+  void genCoraseGridOperator(int l);
+
+  void smoothGS(int l, bool reversedOrder);
+  void calcResidual(int l);
+  Real calcResidualNorm(int l);
+  void solveCG(int l);
+
+  void restrict(int l_dst, const std::vector<Real> &src, std::vector<Real> &dst) const;
+  void interpolate(int l_dst, const std::vector<Real> &src, std::vector<Real> &dst) const;
+
+ private:
+  enum VertexType : char {
+    vtInactive = 0,
+    vtActive = 1,
+    vtActiveTrivial = 2,  // only on finest level 0
+    vtRemoved = 3,        //-+
+    vtZero = 4,           // +-- only during coarse grid generation
+    vtFree = 5            //-+
+  };
+
+  struct CoarseningPath {
+    Vec3i U, W, N;
+    int sc, sf;
+    Real rw, iw;
+    bool inUStencil;
+  };
+
+  int mNumPreSmooth;
+  int mNumPostSmooth;
+  Real mCoarsestLevelAccuracy;
+  Real mTrivialEquationScale;
+
+  std::vector<std::vector<Real>> mA;
+  std::vector<std::vector<Real>> mx;
+  std::vector<std::vector<Real>> mb;
+  std::vector<std::vector<Real>> mr;
+  std::vector<std::vector<VertexType>> mType;
+  std::vector<std::vector<double>> mCGtmp1, mCGtmp2, mCGtmp3, mCGtmp4;
+  std::vector<Vec3i> mSize, mPitch;
+  std::vector<CoarseningPath> mCoarseningPaths0;
+
+  bool mIs3D;
+  int mDim;
+  int mStencilSize;
+  int mStencilSize0;
+  Vec3i mStencilMin;
+  Vec3i mStencilMax;
+
+  bool mIsASet;
+  bool mIsRhsSet;
+
+  // provide kernels with access
+  friend struct knActivateVertices;
+  friend struct knActivateCoarseVertices;
+  friend struct knSetRhs;
+  friend struct knGenCoarseGridOperator;
+  friend struct knSmoothColor;
+  friend struct knCalcResidual;
+  friend struct knResidualNormSumSqr;
+  friend struct knRestrict;
+  friend struct knInterpolate;
+};  // GridMg
+
+}  // namespace Manta
+
+#endif