Cycles: add support for motion blurring of fluid meshes.

Reviewed By: brecht

Differential Revision: https://developer.blender.org/D2063

intern/cycles/blender/blender_mesh.cpp

@@ -680,6 +680,43 @@ static void create_subd_mesh(Scene *scene,
 
 /* Sync */
 
+static void sync_mesh_fluid_motion(BL::Object& b_ob, Scene *scene, Mesh *mesh)
+{
+	if(scene->need_motion() == Scene::MOTION_NONE)
+		return;
+
+	BL::DomainFluidSettings b_fluid_domain = object_fluid_domain_find(b_ob);
+
+	if(!b_fluid_domain)
+		return;
+
+	/* If the mesh has modifiers following the fluid domain we can't export motion. */
+	if(b_fluid_domain.fluid_mesh_vertices.length() != mesh->verts.size())
+		return;
+
+	/* Find or add attribute */
+	float3 *P = &mesh->verts[0];
+	Attribute *attr_mP = mesh->attributes.find(ATTR_STD_MOTION_VERTEX_POSITION);
+
+	if(!attr_mP) {
+		attr_mP = mesh->attributes.add(ATTR_STD_MOTION_VERTEX_POSITION);
+	}
+
+	/* Only export previous and next frame, we don't have any in between data. */
+	float motion_times[2] = {-1.0f, 1.0f};
+	for (int step = 0; step < 2; step++) {
+		float relative_time = motion_times[step] * scene->motion_shutter_time() * 0.5f;
+		float3 *mP = attr_mP->data_float3() + step*mesh->verts.size();
+
+		BL::DomainFluidSettings::fluid_mesh_vertices_iterator fvi;
+		int i = 0;
+
+		for(b_fluid_domain.fluid_mesh_vertices.begin(fvi); fvi != b_fluid_domain.fluid_mesh_vertices.end(); ++fvi, ++i) {
+			mP[i] = P[i] + get_float3(fvi->velocity()) * relative_time;
+		}
+	}
+}
+
 Mesh *BlenderSync::sync_mesh(BL::Object& b_ob,
                              bool object_updated,
                              bool hide_tris)
@@ -821,6 +858,9 @@ Mesh *BlenderSync::sync_mesh(BL::Object& b_ob,
 			mesh->displacement_method = Mesh::DISPLACE_BOTH;
 	}
 
+	/* fluid motion */
+	sync_mesh_fluid_motion(b_ob, scene, mesh);
+
 	/* tag update */
 	bool rebuild = false;
 
@@ -910,6 +950,11 @@ void BlenderSync::sync_mesh_motion(BL::Object& b_ob,
 	 * would need a more extensive check to see which objects are animated */
 	BL::Mesh b_mesh(PointerRNA_NULL);
 
+	/* fluid motion is exported immediate with mesh, skip here */
+	BL::DomainFluidSettings b_fluid_domain = object_fluid_domain_find(b_ob);
+	if (b_fluid_domain)
+		return;
+
 	if(ccl::BKE_object_is_deform_modified(b_ob, b_scene, preview)) {
 		/* get derived mesh */
 		b_mesh = object_to_mesh(b_data, b_ob, b_scene, true, !preview, false);

intern/cycles/blender/blender_object.cpp

@@ -719,12 +719,7 @@ void BlenderSync::sync_motion(BL::RenderSettings& b_render,
 		        << relative_time << ".";
 
 		/* fixed shutter time to get previous and next frame for motion pass */
-		float shuttertime;
-
-		if(scene->need_motion() == Scene::MOTION_PASS)
-			shuttertime = 2.0f;
-		else
-			shuttertime = scene->camera->shuttertime;
+		float shuttertime = scene->motion_shutter_time();
 
 		/* compute frame and subframe time */
 		float time = frame_center + frame_center_delta + relative_time * shuttertime * 0.5f;

intern/cycles/blender/blender_sync.h

@@ -131,7 +131,9 @@ private:
 	                Transform& tfm,
 	                bool *use_portal);
 	void sync_background_light(bool use_portal);
-	void sync_mesh_motion(BL::Object& b_ob, Object *object, float motion_time);
+	void sync_mesh_motion(BL::Object& b_ob,
+	                      Object *object,
+	                      float motion_time);
 	void sync_camera_motion(BL::RenderSettings& b_render,
 	                        BL::Object& b_ob,
 	                        int width, int height,

intern/cycles/blender/blender_util.h

@@ -519,6 +519,23 @@ static inline BL::SmokeDomainSettings object_smoke_domain_find(BL::Object& b_ob)
 	return BL::SmokeDomainSettings(PointerRNA_NULL);
 }
 
+static inline BL::DomainFluidSettings object_fluid_domain_find(BL::Object b_ob)
+{
+	BL::Object::modifiers_iterator b_mod;
+
+	for(b_ob.modifiers.begin(b_mod); b_mod != b_ob.modifiers.end(); ++b_mod) {
+		if(b_mod->is_a(&RNA_FluidSimulationModifier)) {
+			BL::FluidSimulationModifier b_fmd(*b_mod);
+			BL::FluidSettings fss = b_fmd.settings();
+
+			if(fss.type() == BL::FluidSettings::type_DOMAIN)
+				return (BL::DomainFluidSettings)b_fmd.settings();
+		}
+	}
+
+	return BL::DomainFluidSettings(PointerRNA_NULL);
+}
+
 /* ID Map
  *
  * Utility class to keep in sync with blender data.

intern/cycles/render/scene.cpp

@@ -263,6 +263,14 @@ Scene::MotionType Scene::need_motion(bool advanced_shading)
 		return MOTION_NONE;
 }
 
+float Scene::motion_shutter_time()
+{
+	if(need_motion() == Scene::MOTION_PASS)
+		return 2.0f;
+	else
+		return camera->shuttertime;
+}
+
 bool Scene::need_global_attribute(AttributeStandard std)
 {
 	if(std == ATTR_STD_UV)

intern/cycles/render/scene.h

@@ -213,6 +213,7 @@ public:
 
 	enum MotionType { MOTION_NONE = 0, MOTION_PASS, MOTION_BLUR };
 	MotionType need_motion(bool advanced_shading = true);
+	float motion_shutter_time();
 
 	bool need_update();
 	bool need_reset();

source/blender/makesrna/intern/rna_fluidsim.c

@@ -204,18 +204,6 @@ static char *rna_FluidSettings_path(PointerRNA *ptr)
 	return BLI_sprintfN("modifiers[\"%s\"].settings", name_esc);
 }
 
-static void rna_FluidMeshVertex_data_begin(CollectionPropertyIterator *iter, PointerRNA *ptr)
-{
-	FluidsimSettings *fss = (FluidsimSettings *)ptr->data;
-	rna_iterator_array_begin(iter, fss->meshVelocities, sizeof(float) * 3, fss->totvert, 0, NULL);
-}
-
-static int rna_FluidMeshVertex_data_length(PointerRNA *ptr)
-{
-	FluidsimSettings *fss = (FluidsimSettings *)ptr->data;
-	return fss->totvert;
-}
-
 #else
 
 static void rna_def_fluidsim_slip(StructRNA *srna)
@@ -251,9 +239,8 @@ static void rna_def_fluid_mesh_vertices(BlenderRNA *brna)
 	StructRNA *srna;
 	PropertyRNA *prop;
 	
-	srna = RNA_def_struct(brna, "FluidMeshVertex", NULL);
-	RNA_def_struct_sdna(srna, "FluidVertexVelocity");
-	RNA_def_struct_ui_text(srna, "Fluid Mesh Vertex", "Vertex of a simulated fluid mesh");
+	srna = RNA_def_struct(brna, "FluidVertexVelocity", NULL);
+	RNA_def_struct_ui_text(srna, "Fluid Mesh Velocity", "Velocity of a simulated fluid mesh");
 	RNA_def_struct_ui_icon(srna, ICON_VERTEXSEL);
 
 	prop = RNA_def_property(srna, "velocity", PROP_FLOAT, PROP_VELOCITY);
@@ -442,11 +429,10 @@ static void rna_def_fluidsim_domain(BlenderRNA *brna)
 	
 	/* simulated fluid mesh data */
 	prop = RNA_def_property(srna, "fluid_mesh_vertices", PROP_COLLECTION, PROP_NONE);
-	RNA_def_property_struct_type(prop, "FluidMeshVertex");
+	RNA_def_property_collection_sdna(prop, NULL, "meshVelocities", "totvert");
+	RNA_def_property_struct_type(prop, "FluidVertexVelocity");
 	RNA_def_property_ui_text(prop, "Fluid Mesh Vertices", "Vertices of the fluid mesh generated by simulation");
-	RNA_def_property_collection_funcs(prop, "rna_FluidMeshVertex_data_begin", "rna_iterator_array_next",
-	                                  "rna_iterator_array_end", "rna_iterator_array_get",
-	                                  "rna_FluidMeshVertex_data_length", NULL, NULL, NULL);
+
 	rna_def_fluid_mesh_vertices(brna);
 }