Smoke: expose empty space clipping property to the UI.

This is used to determine which voxels are to be considered empty space.

Previously it was hardcoded for converting dense grids to OpenVDB grids
to reduce disk space usage.

This value is also useful for rendering engines to know, i.e. to
optimize ray marching.

6 files changed, 48 insertions, 17 deletions

diff --git a/source/blender/blenkernel/BKE_blender_version.h b/source/blender/blenkernel/BKE_blender_version.h
index c99da724794..6cd93e19e95 100644
--- a/source/blender/blenkernel/BKE_blender_version.h
+++ b/source/blender/blenkernel/BKE_blender_version.h
@@ -28,7 +28,7 @@
  * and keep comment above the defines.
  * Use STRINGIFY() rather than defining with quotes */
 #define BLENDER_VERSION         279
-#define BLENDER_SUBVERSION      2
+#define BLENDER_SUBVERSION      3
 /* Several breakages with 270, e.g. constraint deg vs rad */
 #define BLENDER_MINVERSION      270
 #define BLENDER_MINSUBVERSION   6
diff --git a/source/blender/blenkernel/intern/pointcache.c b/source/blender/blenkernel/intern/pointcache.c
index a84dc056015..5b36b0f9f84 100644
--- a/source/blender/blenkernel/intern/pointcache.c
+++ b/source/blender/blenkernel/intern/pointcache.c
@@ -972,20 +972,20 @@ static int ptcache_smoke_openvdb_write(struct OpenVDBWriter *writer, void *smoke
 
 		smoke_turbulence_export(sds->wt, &dens, &react, &flame, &fuel, &r, &g, &b, &tcu, &tcv, &tcw);
 
-		wt_density_grid = OpenVDB_export_grid_fl(writer, "density", dens, sds->res_wt, sds->fluidmat_wt, NULL);
+		wt_density_grid = OpenVDB_export_grid_fl(writer, "density", dens, sds->res_wt, sds->fluidmat_wt, sds->clipping, NULL);
 		clip_grid = wt_density_grid;
 
 		if (fluid_fields & SM_ACTIVE_FIRE) {
-			OpenVDB_export_grid_fl(writer, "flame", flame, sds->res_wt, sds->fluidmat_wt, wt_density_grid);
-			OpenVDB_export_grid_fl(writer, "fuel", fuel, sds->res_wt, sds->fluidmat_wt, wt_density_grid);
-			OpenVDB_export_grid_fl(writer, "react", react, sds->res_wt, sds->fluidmat_wt, wt_density_grid);
+			OpenVDB_export_grid_fl(writer, "flame", flame, sds->res_wt, sds->fluidmat_wt, sds->clipping, wt_density_grid);
+			OpenVDB_export_grid_fl(writer, "fuel", fuel, sds->res_wt, sds->fluidmat_wt, sds->clipping, wt_density_grid);
+			OpenVDB_export_grid_fl(writer, "react", react, sds->res_wt, sds->fluidmat_wt, sds->clipping, wt_density_grid);
 		}
 
 		if (fluid_fields & SM_ACTIVE_COLORS) {
-			OpenVDB_export_grid_vec(writer, "color", r, g, b, sds->res_wt, sds->fluidmat_wt, VEC_INVARIANT, true, wt_density_grid);
+			OpenVDB_export_grid_vec(writer, "color", r, g, b, sds->res_wt, sds->fluidmat_wt, VEC_INVARIANT, true, sds->clipping, wt_density_grid);
 		}
 
-		OpenVDB_export_grid_vec(writer, "texture coordinates", tcu, tcv, tcw, sds->res, sds->fluidmat, VEC_INVARIANT, false, wt_density_grid);
+		OpenVDB_export_grid_vec(writer, "texture coordinates", tcu, tcv, tcw, sds->res, sds->fluidmat, VEC_INVARIANT, false, sds->clipping, wt_density_grid);
 	}
 
 	if (sds->fluid) {
@@ -1000,32 +1000,32 @@ static int ptcache_smoke_openvdb_write(struct OpenVDBWriter *writer, void *smoke
 		OpenVDBWriter_add_meta_fl(writer, "blender/smoke/dt", dt);
 
 		const char *name = (!sds->wt) ? "density" : "density_low";
-		density_grid = OpenVDB_export_grid_fl(writer, name, dens, sds->res, sds->fluidmat, NULL);
+		density_grid = OpenVDB_export_grid_fl(writer, name, dens, sds->res, sds->fluidmat, sds->clipping, NULL);
 		clip_grid = sds->wt ? clip_grid : density_grid;
 
-		OpenVDB_export_grid_fl(writer, "shadow", sds->shadow, sds->res, sds->fluidmat, NULL);
+		OpenVDB_export_grid_fl(writer, "shadow", sds->shadow, sds->res, sds->fluidmat, sds->clipping, NULL);
 
 		if (fluid_fields & SM_ACTIVE_HEAT) {
-			OpenVDB_export_grid_fl(writer, "heat", heat, sds->res, sds->fluidmat, clip_grid);
-			OpenVDB_export_grid_fl(writer, "heat_old", heatold, sds->res, sds->fluidmat, clip_grid);
+			OpenVDB_export_grid_fl(writer, "heat", heat, sds->res, sds->fluidmat, sds->clipping, clip_grid);
+			OpenVDB_export_grid_fl(writer, "heat_old", heatold, sds->res, sds->fluidmat, sds->clipping, clip_grid);
 		}
 
 		if (fluid_fields & SM_ACTIVE_FIRE) {
 			name = (!sds->wt) ? "flame" : "flame_low";
-			OpenVDB_export_grid_fl(writer, name, flame, sds->res, sds->fluidmat, density_grid);
+			OpenVDB_export_grid_fl(writer, name, flame, sds->res, sds->fluidmat, sds->clipping, density_grid);
 			name = (!sds->wt) ? "fuel" : "fuel_low";
-			OpenVDB_export_grid_fl(writer, name, fuel, sds->res, sds->fluidmat, density_grid);
+			OpenVDB_export_grid_fl(writer, name, fuel, sds->res, sds->fluidmat, sds->clipping, density_grid);
 			name = (!sds->wt) ? "react" : "react_low";
-			OpenVDB_export_grid_fl(writer, name, react, sds->res, sds->fluidmat, density_grid);
+			OpenVDB_export_grid_fl(writer, name, react, sds->res, sds->fluidmat, sds->clipping, density_grid);
 		}
 
 		if (fluid_fields & SM_ACTIVE_COLORS) {
 			name = (!sds->wt) ? "color" : "color_low";
-			OpenVDB_export_grid_vec(writer, name, r, g, b, sds->res, sds->fluidmat, VEC_INVARIANT, true, density_grid);
+			OpenVDB_export_grid_vec(writer, name, r, g, b, sds->res, sds->fluidmat, VEC_INVARIANT, true, sds->clipping, density_grid);
 		}
 
-		OpenVDB_export_grid_vec(writer, "velocity", vx, vy, vz, sds->res, sds->fluidmat, VEC_CONTRAVARIANT_RELATIVE, false, clip_grid);
-		OpenVDB_export_grid_ch(writer, "obstacles", obstacles, sds->res, sds->fluidmat, NULL);
+		OpenVDB_export_grid_vec(writer, "velocity", vx, vy, vz, sds->res, sds->fluidmat, VEC_CONTRAVARIANT_RELATIVE, false, sds->clipping, clip_grid);
+		OpenVDB_export_grid_ch(writer, "obstacles", obstacles, sds->res, sds->fluidmat, sds->clipping, NULL);
 	}
 
 	return 1;
diff --git a/source/blender/blenkernel/intern/smoke.c b/source/blender/blenkernel/intern/smoke.c
index 86e69e68c11..bf473603c0e 100644
--- a/source/blender/blenkernel/intern/smoke.c
+++ b/source/blender/blenkernel/intern/smoke.c
@@ -551,6 +551,8 @@ void smokeModifier_createType(struct SmokeModifierData *smd)
 
 			smd->domain->coba = NULL;
 			smd->domain->coba_field = FLUID_FIELD_DENSITY;
+
+			smd->domain->clipping = 1e-3f;
 		}
 		else if (smd->type & MOD_SMOKE_TYPE_FLOW)
 		{
diff --git a/source/blender/blenloader/intern/versioning_270.c b/source/blender/blenloader/intern/versioning_270.c
index d27c1ce16d3..f1c40aae399 100644
--- a/source/blender/blenloader/intern/versioning_270.c
+++ b/source/blender/blenloader/intern/versioning_270.c
@@ -1735,6 +1735,24 @@ void blo_do_versions_270(FileData *fd, Library *UNUSED(lib), Main *main)
 		}
 	}
 
+	if (!MAIN_VERSION_ATLEAST(main, 279, 3)) {
+		if (!DNA_struct_elem_find(fd->filesdna, "SmokeDomainSettings", "float", "clipping")) {
+			Object *ob;
+			ModifierData *md;
+
+			for (ob = main->object.first; ob; ob = ob->id.next) {
+				for (md = ob->modifiers.first; md; md = md->next) {
+					if (md->type == eModifierType_Smoke) {
+						SmokeModifierData *smd = (SmokeModifierData *)md;
+						if (smd->domain) {
+							smd->domain->clipping = 1e-3f;
+						}
+					}
+				}
+			}
+		}
+	}
+
 	{
 		/* Fix for invalid state of screen due to bug in older versions. */
 		for (bScreen *sc = main->screen.first; sc; sc = sc->id.next) {
diff --git a/source/blender/makesdna/DNA_smoke_types.h b/source/blender/makesdna/DNA_smoke_types.h
index 9932e16e988..c1565bde882 100644
--- a/source/blender/makesdna/DNA_smoke_types.h
+++ b/source/blender/makesdna/DNA_smoke_types.h
@@ -217,6 +217,9 @@ typedef struct SmokeDomainSettings {
 	char use_coba;
 	char coba_field;  /* simulation field used for the color mapping */
 	char pad2;
+
+	float clipping;
+	float pad3;
 } SmokeDomainSettings;
 
 
diff --git a/source/blender/makesrna/intern/rna_smoke.c b/source/blender/makesrna/intern/rna_smoke.c
index 1db64100d94..54daba706c7 100644
--- a/source/blender/makesrna/intern/rna_smoke.c
+++ b/source/blender/makesrna/intern/rna_smoke.c
@@ -898,6 +898,14 @@ static void rna_def_smoke_domain_settings(BlenderRNA *brna)
 	RNA_def_property_struct_type(prop, "ColorRamp");
 	RNA_def_property_ui_text(prop, "Color Ramp", "");
 	RNA_def_property_update(prop, NC_OBJECT | ND_DRAW, NULL);
+
+	prop = RNA_def_property(srna, "clipping", PROP_FLOAT, PROP_NONE);
+	RNA_def_property_float_sdna(prop, NULL, "clipping");
+	RNA_def_property_range(prop, 0.0, 1.0);
+	RNA_def_property_ui_range(prop, 0.0, 1.0, 0.1, 3);
+	RNA_def_property_ui_text(prop, "Clipping",
+							 "Value under which voxels are considered empty space to optimize caching or rendering");
+	RNA_def_property_update(prop, NC_OBJECT | ND_MODIFIER, NULL);
 }
 
 static void rna_def_smoke_flow_settings(BlenderRNA *brna)