Elbeem / Fluidsim update:

a) Enable the possibility to remove the "air bubble" around submerged collision object. This feature is enabled as standard for new files. The code was found in elbeem by nudelZ, coded and provided by Nils Thürey (thanks!)
b) Old baked files gets deleted if a new bake gets started (were overwritten before and resulted in weird old bake + new bake mixture) (idea by nudelZ)

intern/elbeem/extern/elbeem.h

@@ -77,6 +77,10 @@ typedef struct elbeemSimulationSettings {
 	/* boundary types and settings for domain walls */
 	short domainobsType;
 	float domainobsPartslip;
+
+	/* what surfaces to generate */
+	int mFsSurfGenSetting;
+
 	/* generate speed vectors for vertices (e.g. for image based motion blur)*/
 	short generateVertexVectors;
 	/* strength of surface smoothing */
@@ -108,10 +112,12 @@ typedef struct elbeemSimulationSettings {
 #define OB_FLUIDSIM_PARTICLE    64
 #define OB_FLUIDSIM_CONTROL 	128
 
-// defines for elbeemMesh->obstacleType below
+// defines for elbeemMesh->obstacleType below (low bits) high bits (>=64) are reserved for mFsSurfGenSetting flags which are defined in solver_class.h
 #define FLUIDSIM_OBSTACLE_NOSLIP     1
 #define FLUIDSIM_OBSTACLE_PARTSLIP   2
 #define FLUIDSIM_OBSTACLE_FREESLIP   3
+#define FLUIDSIM_FSSG_NOOBS			 64
+
 
 #define OB_VOLUMEINIT_VOLUME 1
 #define OB_VOLUMEINIT_SHELL  2

intern/elbeem/intern/simulation_object.cpp

@@ -181,6 +181,9 @@ int SimulationObject::initializeLbmSimulation(ntlRenderGlobals *glob)
 		mpLbm->setGenerateParticles(mpElbeemSettings->generateParticles);
 		// set initial particles
 		mpParts->setNumInitialParticles(mpElbeemSettings->numTracerParticles);
+		
+		// surface generation flag
+		mpLbm->setSurfGenSettings(mpElbeemSettings->mFsSurfGenSetting);
 
 		string dinitType = string("no");
 		if     (mpElbeemSettings->domainobsType==FLUIDSIM_OBSTACLE_PARTSLIP) dinitType = string("part"); 

intern/elbeem/intern/solver_class.h

@@ -308,6 +308,9 @@ class LbmFsgrSolver :
 		//! for raytracing, preprocess
 		void prepareVisualization( void );
 
+		/* surface generation settings */
+		virtual void setSurfGenSettings(short value);
+
 	protected:
 
 		//! internal quick print function (for debugging) 

intern/elbeem/intern/solver_init.cpp

@@ -538,6 +538,15 @@ void LbmFsgrSolver::parseAttrList()
 }
 
 
+/******************************************************************************
+ * (part of enabling chapter 6 of "Free Surface Flows with Moving and Deforming Objects for LBM")
+ *****************************************************************************/
+void LbmFsgrSolver::setSurfGenSettings(short value)
+{
+	mFsSurfGenSetting = value;
+}
+
+
 /******************************************************************************
  * Initialize omegas and forces on all levels (for init/timestep change)
  *****************************************************************************/

intern/elbeem/intern/solver_interface.h

@@ -271,6 +271,9 @@ class LbmSolverInterface
 		/*! debug object display */
 		virtual vector<ntlGeometryObject*> getDebugObjects() { vector<ntlGeometryObject*> empty(0); return empty; }
 
+		/* surface generation settings */
+		virtual void setSurfGenSettings(short value) = 0;
+
 #if LBM_USE_GUI==1
 		/*! show simulation info */
 		virtual void debugDisplay(int) = 0;

release/scripts/startup/bl_ui/properties_physics_fluid.py

@@ -257,6 +257,7 @@ class PHYSICS_PT_domain_boundary(PhysicButtonsPanel, bpy.types.Panel):
         col.prop(fluid, "slip_type", text="")
         if fluid.slip_type == 'PARTIALSLIP':
             col.prop(fluid, "partial_slip_factor", slider=True, text="Amount")
+        col.prop(fluid, "surface_noobs")
 
         col = split.column()
         col.label(text="Surface:")

source/blender/editors/physics/physics_fluid.c

@@ -56,6 +56,7 @@
 #include "DNA_object_fluidsim.h"	
 
 #include "BLI_blenlib.h"
+#include "BLI_fileops.h"
 #include "BLI_threads.h"
 #include "BLI_math.h"
 #include "BLI_utildefines.h"
@@ -125,7 +126,7 @@ static void get_fluid_gravity(float *gravity, Scene *scene, FluidsimSettings *fs
 	if (scene->physics_settings.flag & PHYS_GLOBAL_GRAVITY) {
 		copy_v3_v3(gravity, scene->physics_settings.gravity);
 	} else {
-		copy_v3_v3(gravity, &fss->gravx);
+		copy_v3_v3(gravity, fss->grav);
 	}
 }
 
@@ -442,8 +443,8 @@ static void fluid_init_all_channels(bContext *C, Object *UNUSED(fsDomain), Fluid
 		for (fobj=fobjects->first; fobj; fobj=fobj->next) {
 			Object *ob = fobj->object;
 			FluidsimModifierData *fluidmd = (FluidsimModifierData *)modifiers_findByType(ob, eModifierType_Fluidsim);
-			float active= (float)(fluidmd->fss->flag & OB_FLUIDSIM_ACTIVE);
+			float active= (float)(fluidmd->fss->flag && OB_FLUIDSIM_ACTIVE);
-			float rot_d[3], old_rot[3] = {0.f, 0.f, 0.f};
+			float rot_d[3] = {0.f, 0.f, 0.f}, old_rot[3] = {0.f, 0.f, 0.f};
 			
 			if (ELEM(fluidmd->fss->type, OB_FLUIDSIM_DOMAIN, OB_FLUIDSIM_PARTICLE))
 				continue;
@@ -809,6 +810,44 @@ static void fluidbake_free_data(FluidAnimChannels *channels, ListBase *fobjects,
 	}
 }
 
+/* copied from rna_fluidsim.c: fluidsim_find_lastframe() */
+static void fluidsim_delete_until_lastframe(FluidsimSettings *fss)
+{
+	char targetDir[FILE_MAXFILE+FILE_MAXDIR], targetFile[FILE_MAXFILE+FILE_MAXDIR];
+	char targetDirVel[FILE_MAXFILE+FILE_MAXDIR], targetFileVel[FILE_MAXFILE+FILE_MAXDIR];
+	char previewDir[FILE_MAXFILE+FILE_MAXDIR], previewFile[FILE_MAXFILE+FILE_MAXDIR];
+	int curFrame = 1, exists = 0;
+
+	BLI_snprintf(targetDir, sizeof(targetDir), "%sfluidsurface_final_####.bobj.gz", fss->surfdataPath);
+	BLI_snprintf(targetDirVel, sizeof(targetDir), "%sfluidsurface_final_####.bvel.gz", fss->surfdataPath);
+	BLI_snprintf(previewDir, sizeof(targetDir), "%sfluidsurface_preview_####.bobj.gz", fss->surfdataPath);
+
+	BLI_path_abs(targetDir, G.main->name);
+	BLI_path_abs(targetDirVel, G.main->name);
+	BLI_path_abs(previewDir, G.main->name);
+
+	do {
+		BLI_strncpy(targetFile, targetDir, sizeof(targetFile));
+		BLI_strncpy(targetFileVel, targetDirVel, sizeof(targetFileVel));
+		BLI_strncpy(previewFile, previewDir, sizeof(previewFile));
+
+		BLI_path_frame(targetFile, curFrame, 0);
+		BLI_path_frame(targetFileVel, curFrame, 0);
+		BLI_path_frame(previewFile, curFrame, 0);
+
+		curFrame++;
+
+		if(exists = BLI_exist(targetFile))
+		{
+			BLI_delete(targetFile, 0, 0);
+			BLI_delete(targetFileVel, 0, 0);
+			BLI_delete(previewFile, 0, 0);
+		}
+	} while(exists);
+
+	return;
+}
+
 static int fluidsimBake(bContext *C, ReportList *reports, Object *fsDomain)
 {
 	Scene *scene= CTX_data_scene(C);
@@ -878,6 +917,9 @@ static int fluidsimBake(bContext *C, ReportList *reports, Object *fsDomain)
 	
 	// reset last valid frame
 	domainSettings->lastgoodframe = -1;
+
+	/* delete old baked files */
+	fluidsim_delete_until_lastframe(domainSettings);
 	
 	/* rough check of settings... */
 	if(domainSettings->previewresxyz > domainSettings->resolutionxyz) {
@@ -1018,6 +1060,13 @@ static int fluidsimBake(bContext *C, ReportList *reports, Object *fsDomain)
 	else if (domainSettings->typeFlags&OB_FSBND_PARTSLIP)	fsset->domainobsType = FLUIDSIM_OBSTACLE_PARTSLIP;
 	else if (domainSettings->typeFlags&OB_FSBND_FREESLIP)	fsset->domainobsType = FLUIDSIM_OBSTACLE_FREESLIP;
 	fsset->domainobsPartslip = domainSettings->partSlipValue;
+
+	/* use domainobsType also for surface generation flag (bit: >=64) */
+	if(domainSettings->typeFlags & OB_FSSG_NOOBS)
+		fsset->mFsSurfGenSetting = FLUIDSIM_FSSG_NOOBS;
+	else
+		fsset->mFsSurfGenSetting = 0; // "normal" mode
+
 	fsset->generateVertexVectors = (domainSettings->domainNovecgen==0);
 
 	// init blender domain transform matrix

source/blender/makesdna/DNA_object_fluidsim.h

@@ -69,7 +69,7 @@ typedef struct FluidsimSettings {
 	short viscosityMode;
 	short viscosityExponent;
 	/* gravity strength */
-	float gravx,gravy,gravz;
+	float grav[3];
 	/* anim start end time (in seconds) */
 	float animStart, animEnd;
 	/* bake start end time (in blender frames) */
@@ -161,6 +161,9 @@ typedef struct FluidsimSettings {
 #define OB_FSBND_FREESLIP       (1<<(OB_TYPEFLAG_START+4))
 #define OB_FSINFLOW_LOCALCOORD  (1<<(OB_TYPEFLAG_START+5))
 
+/* surface generation flag (part of enabling chapter 6 of "Free Surface Flows with Moving and Deforming Objects for LBM") */
+#define OB_FSSG_NOOBS			(1<<(OB_TYPEFLAG_START+6))
+
 // guiDisplayMode particle flags
 #define OB_FSDOM_GEOM     1
 #define OB_FSDOM_PREVIEW  2

source/blender/makesrna/intern/rna_fluidsim.c

@@ -312,7 +312,7 @@ static void rna_def_fluidsim_domain(BlenderRNA *brna)
 
 	/* advanced settings */
 	prop= RNA_def_property(srna, "gravity", PROP_FLOAT, PROP_ACCELERATION);
-	RNA_def_property_float_sdna(prop, NULL, "gravx");
+	RNA_def_property_float_sdna(prop, NULL, "grav");
 	RNA_def_property_array(prop, 3);
 	RNA_def_property_range(prop, -1000.1, 1000.1);
 	RNA_def_property_ui_text(prop, "Gravity", "Gravity in X, Y and Z direction");
@@ -384,6 +384,12 @@ static void rna_def_fluidsim_domain(BlenderRNA *brna)
 	RNA_def_property_clear_flag(prop, PROP_ANIMATABLE);
 	RNA_def_property_ui_text(prop, "Generate Speed Vectors", "Generate speed vectors for vector blur");
 
+	/* no collision object surface */
+	prop= RNA_def_property(srna, "surface_noobs", PROP_BOOLEAN, PROP_NONE);
+	RNA_def_property_boolean_sdna(prop, NULL, "typeFlags", OB_FSSG_NOOBS);
+	RNA_def_property_clear_flag(prop, PROP_ANIMATABLE);
+	RNA_def_property_ui_text(prop, "Hide fluid surface", "");
+
 	/* particles */
 
 	prop= RNA_def_property(srna, "tracer_particles", PROP_INT, PROP_NONE);

source/blender/modifiers/intern/MOD_fluidsim_util.c

@@ -90,10 +90,10 @@ void fluidsim_init(FluidsimModifierData *fluidmd)
 		fss->viscosityValue = 1.0;
 		fss->viscosityExponent = 6;
 		
-		// dg TODO: change this to []
+		fss->grav[0] = 0.0;
-		fss->gravx = 0.0;
+		fss->grav[1] = 0.0;
-		fss->gravy = 0.0;
+		fss->grav[2] = -9.81;
-		fss->gravz = -9.81;
+
 		fss->animStart = 0.0; 
 		fss->animEnd = 4.0;
 		fss->gstar = 0.005; // used as normgstar
@@ -111,7 +111,7 @@ void fluidsim_init(FluidsimModifierData *fluidmd)
 		// no bounding box needed
 		
 		// todo - reuse default init from elbeem!
-		fss->typeFlags = OB_FSBND_PARTSLIP;
+		fss->typeFlags = OB_FSBND_PARTSLIP | OB_FSSG_NOOBS;
 		fss->domainNovecgen = 0;
 		fss->volumeInitType = 1; // volume
 		fss->partSlipValue = 0.2;