Liquid Simulation Display Options (GSoC 2020)

All the changes made in the branch `soc-2020-fluid-tools` are included in this patch.

**Major changes:**

=== Viewport Display ===

- //Raw voxel display// or //closest (nearest-neighbor)// interpolation for displaying the underlying voxel data of the simulation grids more clearly.
- An option to display //gridlines// when the slicing method is //single//.

==== Grid Display ====

- Visualization for flags, pressure and level-set representation grids with a fixed color coding based on Manta GUI.

==== Vector Display ====

- //**M**arker **A**nd **C**ell// grid visualization options for vector grids like velocity or external forces.
- Made vector display options available for external forces.

==== Coloring options for //gridlines// ====

- Range highlighting and cell filtering options for displaying the simulation grid data more precisely.
- Color gridlines with flags.

- Also, made slicing and interpolation options available for Volume Object.

Reviewed By: JacquesLucke, sebbas

Differential Revision: https://developer.blender.org/D8705

4 files changed, 17 insertions, 0 deletions

diff --git a/intern/mantaflow/extern/manta_fluid_API.h b/intern/mantaflow/extern/manta_fluid_API.h
index 124671467f7..6827ac35050 100644
--- a/intern/mantaflow/extern/manta_fluid_API.h
+++ b/intern/mantaflow/extern/manta_fluid_API.h
@@ -109,6 +109,8 @@ float *manta_get_phiobs_in(struct MANTA *fluid);
 float *manta_get_phiobsstatic_in(struct MANTA *fluid);
 float *manta_get_phiout_in(struct MANTA *fluid);
 float *manta_get_phioutstatic_in(struct MANTA *fluid);
+float *manta_get_phi(struct MANTA *fluid);
+float *manta_get_pressure(struct MANTA *fluid);
 
 /* Smoke functions */
 void manta_smoke_export_script(struct MANTA *smoke, struct FluidModifierData *fmd);
diff --git a/intern/mantaflow/intern/MANTA_main.cpp b/intern/mantaflow/intern/MANTA_main.cpp
index 8d92d616e15..9d5b3efb0bc 100644
--- a/intern/mantaflow/intern/MANTA_main.cpp
+++ b/intern/mantaflow/intern/MANTA_main.cpp
@@ -118,6 +118,7 @@ MANTA::MANTA(int *res, FluidModifierData *fmd) : mCurrentID(++solverID)
   mFuelIn = nullptr;
   mReactIn = nullptr;
   mEmissionIn = nullptr;
+  mPressure = nullptr;
 
   /* Smoke high res grids. */
   mDensityHigh = nullptr;
@@ -2020,6 +2021,7 @@ void MANTA::updatePointers(FluidModifierData *fmd, bool flush)
   mForceX = (smoke || liquid) ? getPointer<float>("x_force" + s_ext, func) : nullptr;
   mForceY = (smoke || liquid) ? getPointer<float>("y_force" + s_ext, func) : nullptr;
   mForceZ = (smoke || liquid) ? getPointer<float>("z_force" + s_ext, func) : nullptr;
+  mPressure = (smoke || liquid) ? getPointer<float>("pressure" + s_ext, func) : nullptr;
 
   /* Outflow. */
   mPhiOutIn = (outflow) ? getPointer<float>("phiOutIn" + s_ext, func) : nullptr;
diff --git a/intern/mantaflow/intern/MANTA_main.h b/intern/mantaflow/intern/MANTA_main.h
index 5fd94ca01bc..68a5b427e7d 100644
--- a/intern/mantaflow/intern/MANTA_main.h
+++ b/intern/mantaflow/intern/MANTA_main.h
@@ -412,6 +412,10 @@ struct MANTA {
   {
     return mPhi;
   }
+  inline float *getPressure()
+  {
+    return mPressure;
+  }
 
   static atomic<int> solverID;
   static int with_debug; /* On or off (1 or 0), also sets manta debug level. */
@@ -806,6 +810,7 @@ struct MANTA {
   int *mFlags;
   float *mNumObstacle;
   float *mNumGuide;
+  float *mPressure;
 
   /* Smoke grids. */
   float *mDensity;
diff --git a/intern/mantaflow/intern/manta_fluid_API.cpp b/intern/mantaflow/intern/manta_fluid_API.cpp
index 7f96a315a8e..e4754131f34 100644
--- a/intern/mantaflow/intern/manta_fluid_API.cpp
+++ b/intern/mantaflow/intern/manta_fluid_API.cpp
@@ -362,6 +362,14 @@ float *manta_get_phioutstatic_in(MANTA *fluid)
 {
   return fluid->getPhiOutStaticIn();
 }
+float *manta_get_phi(MANTA *fluid)
+{
+  return fluid->getPhi();
+}
+float *manta_get_pressure(MANTA *fluid)
+{
+  return fluid->getPressure();
+}
 
 /* Smoke functions */
 void manta_smoke_export_script(MANTA *smoke, FluidModifierData *fmd)