Fluid: Updated Mantaflow source files

This update introduces two improvements from the Mantaflow repository:

(1) Improved particle sampling:
- Liquid and secondary particles are sampled more predictably. With all parameters being equal, baked particles will be computed at the exact same position during every bake.
- Before, this was not guaranteed.

(2) Sparse grid caching:
- While saving grid data to disk, grids will from now on be saved in a sparse structure whenever possible (e.g. density, flame but not levelsets).
- With the sparse optimization grid cells with a value under the 'Empty Space' value (already present in domain settings) will not be cached.
- The main benefits of this optimization are: Smaller cache sizes and faster playback of simulation data in the viewport.
- This optimization works 'out-of-the-box'. There is no option in the UI to enable it.
- For now, only smoke simulation grids will take advantage of this optimization.

1 files changed, 8 insertions, 8 deletions

diff --git a/extern/mantaflow/preprocessed/plugin/flip.cpp b/extern/mantaflow/preprocessed/plugin/flip.cpp
index 1acdac1c094..eaa1ebe45d5 100644
--- a/extern/mantaflow/preprocessed/plugin/flip.cpp
+++ b/extern/mantaflow/preprocessed/plugin/flip.cpp
@@ -41,7 +41,7 @@ void sampleFlagsWithParticles(const FlagGrid &flags,
   const bool is3D = flags.is3D();
   const Real jlen = randomness / discretization;
   const Vec3 disp(1.0 / discretization, 1.0 / discretization, 1.0 / discretization);
-  RandomStream mRand(9832);
+  RandomStream rand(parts.getSeed());
 
   FOR_IJK_BND(flags, 0)
   {
@@ -53,7 +53,7 @@ void sampleFlagsWithParticles(const FlagGrid &flags,
         for (int dj = 0; dj < discretization; dj++)
           for (int di = 0; di < discretization; di++) {
             Vec3 subpos = pos + disp * Vec3(0.5 + di, 0.5 + dj, 0.5 + dk);
-            subpos += jlen * (Vec3(1, 1, 1) - 2.0 * mRand.getVec3());
+            subpos += jlen * (Vec3(1, 1, 1) - 2.0 * rand.getVec3());
             if (!is3D)
               subpos[2] = 0.5;
             parts.addBuffered(subpos);
@@ -113,7 +113,7 @@ void sampleLevelsetWithParticles(const LevelsetGrid &phi,
   const bool is3D = phi.is3D();
   const Real jlen = randomness / discretization;
   const Vec3 disp(1.0 / discretization, 1.0 / discretization, 1.0 / discretization);
-  RandomStream mRand(9832);
+  RandomStream rand(parts.getSeed());
 
   if (reset) {
     parts.clear();
@@ -132,7 +132,7 @@ void sampleLevelsetWithParticles(const LevelsetGrid &phi,
         for (int dj = 0; dj < discretization; dj++)
           for (int di = 0; di < discretization; di++) {
             Vec3 subpos = pos + disp * Vec3(0.5 + di, 0.5 + dj, 0.5 + dk);
-            subpos += jlen * (Vec3(1, 1, 1) - 2.0 * mRand.getVec3());
+            subpos += jlen * (Vec3(1, 1, 1) - 2.0 * rand.getVec3());
             if (!is3D)
               subpos[2] = 0.5;
             if (phi.getInterpolated(subpos) > 0.)
@@ -205,7 +205,7 @@ void sampleShapeWithParticles(const Shape &shape,
   const bool is3D = flags.is3D();
   const Real jlen = randomness / discretization;
   const Vec3 disp(1.0 / discretization, 1.0 / discretization, 1.0 / discretization);
-  RandomStream mRand(9832);
+  RandomStream rand(parts.getSeed());
 
   if (reset) {
     parts.clear();
@@ -223,7 +223,7 @@ void sampleShapeWithParticles(const Shape &shape,
       for (int dj = 0; dj < discretization; dj++)
         for (int di = 0; di < discretization; di++) {
           Vec3 subpos = pos + disp * Vec3(0.5 + di, 0.5 + dj, 0.5 + dk);
-          subpos += jlen * (Vec3(1, 1, 1) - 2.0 * mRand.getVec3());
+          subpos += jlen * (Vec3(1, 1, 1) - 2.0 * rand.getVec3());
           if (!is3D)
             subpos[2] = 0.5;
           if (exclude && exclude->getInterpolated(subpos) <= 0.)
@@ -576,7 +576,7 @@ void adjustNumber(BasicParticleSystem &parts,
   }
 
   // seed new particles
-  RandomStream mRand(9832);
+  RandomStream rand(parts.getSeed());
   FOR_IJK(tmp)
   {
     int cnt = tmp(i, j, k);
@@ -593,7 +593,7 @@ void adjustNumber(BasicParticleSystem &parts,
 
     if (flags.isFluid(i, j, k) && cnt < minParticles) {
       for (int m = cnt; m < minParticles; m++) {
-        Vec3 pos = Vec3(i, j, k) + mRand.getVec3();
+        Vec3 pos = Vec3(i, j, k) + rand.getVec3();
         // Vec3 pos (i + 0.5, j + 0.5, k + 0.5); // cell center
         parts.addBuffered(pos);
       }