Merge branch 'dev'

10 files changed, 894 insertions, 67 deletions

diff --git a/examples/poiseulle_particles_2d_psm_gpu/sim.cpp b/examples/poiseulle_particles_2d_psm_gpu/sim.cpp
index a8aeabb..7702808 100644
--- a/examples/poiseulle_particles_2d_psm_gpu/sim.cpp
+++ b/examples/poiseulle_particles_2d_psm_gpu/sim.cpp
@@ -83,7 +83,24 @@ saw::error_or<void> setup_initial_conditions(
 		info_f.get_dims(),
 		{{1u,1u}}
 	);
-	
+	// Corners
+	/// Inflow
+	iterator<Desc::D>::apply(
+		[&](auto& index){
+			info_f.at(index).set(5u);
+		},
+		{{0u,0u}},
+		{{1u,dim_y}}
+	);
+	/// Outflow
+	iterator<Desc::D>::apply(
+		[&](auto& index){
+			info_f.at(index).set(5u);
+		},
+		{{dim_x-1u,0u}},
+		{{dim_x, dim_y}}
+	);
+	// Overwrite with
 	// Inflow
 	iterator<Desc::D>::apply(
 		[&](auto& index){
@@ -202,7 +219,7 @@ saw::error_or<void> step(
 
 
 	q.submit([&](acpp::sycl::handler& h){
-		component<T,Desc,cmpt::PSM,encode::Sycl<saw::encode::Native>> collision{0.65};
+		component<T,Desc,cmpt::PSM,encode::Sycl<saw::encode::Native>> collision{0.8};
 		component<T,Desc,cmpt::BounceBack,encode::Sycl<saw::encode::Native>> bb;
 		component<T,Desc,cmpt::AntiBounceBack<0u>,encode::Sycl<saw::encode::Native>> abb;
 
@@ -243,15 +260,19 @@ saw::error_or<void> step(
 					collision.apply(fields,macros,index,t_i);
 					break;
 				case 3u:
-					//flow_in.apply(fields,index,t_i);
-					equi.apply(fields,index,t_i);
+					flow_in.apply(fields,index,t_i);
+					//equi.apply(fields,index,t_i);
 					collision.apply(fields,macros,index,t_i);
 					break;
 				case 4u:
-					// flow_out.apply(fields,index,t_i);
-					equi.apply(fields,index,t_i);
+					flow_out.apply(fields,index,t_i);
+					// equi.apply(fields,index,t_i);
 					collision.apply(fields,macros,index,t_i);
-				break;
+					break;
+				case 5u:
+					// Corners
+					bb.apply(fields,index,t_i);
+					break;
 				default:
 				break;
 			}
@@ -295,12 +316,12 @@ saw::error_or<void> lbm_main(int argc, char** argv){
 
 	converter<T> conv {
 		// delta_x
-		{{1.0}},
+		{{1e-3}},
 		// delta_t
-		{{1.0}}
+		{{1e-06}}
 	};
 	
-	print_lbm_meta<T,Desc>(conv,{0.05},{0.01},{0.4 * dim_y});
+	print_lbm_meta<T,Desc>(conv,{0.1},{1e-2},{0.4 * dim_y *1e-3});
 
 	// saw::data<sch::FixedArray<sch::UInt64,Desc::D>> meta{{dim_x,dim_y}};
 	auto lbm_data_ptr = saw::heap<saw::data<sch::ChunkStruct<T,Desc>>>();
@@ -382,8 +403,7 @@ saw::error_or<void> lbm_main(int argc, char** argv){
 			}
 		}
 		sycl_q.wait();
-		/*
-		{
+		if(i.get() %  1 == 0u){
 			{
 				auto eov = dev.copy_to_host(lbm_sycl_macro_data,*lbm_macro_data_ptr);
 				if(eov.is_error()){
@@ -397,7 +417,6 @@ saw::error_or<void> lbm_main(int argc, char** argv){
 				}
 			}
 		}
-		*/
 		/*
 		{
 			{
diff --git a/examples/settling_cubes_2d_ibm/.nix/derivation.nix b/examples/settling_cubes_2d_ibm/.nix/derivation.nix
new file mode 100644
index 0000000..d7f138b
--- /dev/null
+++ b/examples/settling_cubes_2d_ibm/.nix/derivation.nix
@@ -0,0 +1,41 @@
+{ lib
+, stdenv
+, scons
+, clang-tools
+, forstio
+, python3
+, pname
+, version
+, adaptive-cpp
+, kel
+}:
+
+stdenv.mkDerivation {
+	pname = pname + "-examples-" + "setting_cubes_2d_ibm_gpu";
+	inherit version;
+	src = ./..;
+
+	nativeBuildInputs = [
+		scons
+		clang-tools
+		python3
+	];
+
+	buildInputs = [
+		forstio.core
+		forstio.async
+		forstio.codec
+		forstio.codec-unit
+		forstio.io
+    forstio.remote
+    forstio.remote-filesystem
+		forstio.codec-json
+		adaptive-cpp
+		kel.lbm.core
+		kel.lbm.sycl
+	];
+
+	preferLocalBuild = true;
+
+	outputs = [ "out" "dev" ];
+}
diff --git a/examples/settling_cubes_2d_ibm/SConscript b/examples/settling_cubes_2d_ibm/SConscript
new file mode 100644
index 0000000..ae08056
--- /dev/null
+++ b/examples/settling_cubes_2d_ibm/SConscript
@@ -0,0 +1,34 @@
+#!/bin/false
+
+import os
+import os.path
+import glob
+
+
+Import('env')
+
+dir_path = Dir('.').abspath
+
+# Environment for base library
+examples_env = env.Clone();
+examples_env['CXX'] = 'syclcc-clang';
+examples_env['CXXFLAGS'] += ['-O3'];
+
+examples_env.sources = sorted(glob.glob(dir_path + "/*.cpp"))
+examples_env.headers = sorted(glob.glob(dir_path + "/*.hpp"))
+
+env.sources += examples_env.sources;
+env.headers += examples_env.headers;
+
+# Cavity2D
+examples_objects = [];
+examples_env.add_source_files(examples_objects, ['sim.cpp'], shared=False);
+examples_env.poiseulle_2d_gpu = examples_env.Program('#bin/settling_cubes_2d_ibm_gpu', [examples_objects]);
+
+# Set Alias
+env.examples = [
+	examples_env.poiseulle_2d_gpu
+];
+env.Alias('examples', env.examples);
+env.targets += ['examples'];
+env.Install('$prefix/bin/', env.examples);
diff --git a/examples/settling_cubes_2d_ibm/SConstruct b/examples/settling_cubes_2d_ibm/SConstruct
new file mode 100644
index 0000000..0611b67
--- /dev/null
+++ b/examples/settling_cubes_2d_ibm/SConstruct
@@ -0,0 +1,81 @@
+#!/usr/bin/env python3
+
+import sys
+import os
+import os.path
+import glob
+import re
+
+
+if sys.version_info < (3,):
+    def isbasestring(s):
+        return isinstance(s,basestring)
+else:
+    def isbasestring(s):
+        return isinstance(s, (str,bytes))
+
+def add_kel_source_files(self, sources, filetype, lib_env=None, shared=False, target_post=""):
+
+    if isbasestring(filetype):
+        dir_path = self.Dir('.').abspath
+        filetype = sorted(glob.glob(dir_path+"/"+filetype))
+
+    for path in filetype:
+        target_name = re.sub( r'(.*?)(\.cpp|\.c\+\+)', r'\1' + target_post, path )
+        if shared:
+            target_name+='.os'
+            sources.append( self.SharedObject( target=target_name, source=path ) )
+        else:
+            target_name+='.o'
+            sources.append( self.StaticObject( target=target_name, source=path ) )
+    pass
+
+def isAbsolutePath(key, dirname, env):
+	assert os.path.isabs(dirname), "%r must have absolute path syntax" % (key,)
+
+env_vars = Variables(
+	args=ARGUMENTS
+)
+
+env_vars.Add('prefix',
+	help='Installation target location of build results and headers',
+	default='/usr/local/',
+	validator=isAbsolutePath
+)
+
+env_vars.Add('build_examples',
+	help='If examples should be built',
+	default="true"
+)
+
+env=Environment(ENV=os.environ, variables=env_vars, CPPPATH=[],
+    CPPDEFINES=['SAW_UNIX'],
+    CXXFLAGS=[
+        '-std=c++20',
+        '-g',
+        '-Wall',
+        '-Wextra'
+    ],
+    LIBS=[
+        'forstio-core',
+        'forstio-async',
+        'forstio-io'
+    ]
+);
+env.__class__.add_source_files = add_kel_source_files
+env.Tool('compilation_db');
+env.cdb = env.CompilationDatabase('compile_commands.json');
+
+env.objects = [];
+env.sources = [];
+env.headers = [];
+env.targets = [];
+
+Export('env')
+SConscript('SConscript')
+
+env.Alias('cdb', env.cdb);
+env.Alias('all', [env.targets]);
+env.Default('all');
+
+env.Alias('install', '$prefix')
diff --git a/examples/settling_cubes_2d_ibm/sim.cpp b/examples/settling_cubes_2d_ibm/sim.cpp
new file mode 100644
index 0000000..411efa7
--- /dev/null
+++ b/examples/settling_cubes_2d_ibm/sim.cpp
@@ -0,0 +1,454 @@
+#include <kel/lbm/sycl/lbm.hpp>
+#include <kel/lbm/lbm.hpp>
+#include <kel/lbm/particle.hpp>
+
+#include <forstio/io/io.hpp>
+#include <forstio/remote/filesystem/easy.hpp>
+#include <forstio/codec/json/json.hpp>
+#include <forstio/codec/simple.hpp>
+
+namespace kel {
+namespace lbm {
+
+constexpr uint64_t dim_x = 512ul;
+constexpr uint64_t dim_y = dim_x * 2ul;
+
+constexpr uint64_t particle_amount = 16ul;
+
+namespace sch {
+using namespace saw::schema;
+
+using InfoChunk = Chunk<UInt8, 0u, dim_x, dim_y>;
+
+template<typename T, typename Desc>
+using DfChunk = Chunk<FixedArray<T,Desc::Q>, 1u, dim_x, dim_y>;
+
+template<typename T, typename Desc>
+using ScalarChunk = Chunk<Scalar<T>, 0u, dim_x, dim_y>;
+
+template<typename T, typename Desc>
+using VectorChunk = Chunk<Vector<T,Desc::D>, 0u, dim_x, dim_y>;
+
+template<typename T, typename Desc>
+using ChunkStruct = Struct<
+	Member<InfoChunk, "info">,
+	Member<DfChunk<T,Desc>, "dfs">,
+	Member<DfChunk<T,Desc>, "dfs_old">
+>;
+
+template<typename T, typename Desc>
+using VelChunk = Chunk<Vector<T,Desc::D>, 0u, dim_x, dim_y>;
+
+template<typename T>
+using RhoChunk = Chunk<Scalar<T>, 0u, dim_x, dim_y>;
+
+template<typename T, typename Desc>
+using MacroStruct = Struct<
+	Member<VelChunk<T,Desc>, "velocity">,
+	Member<RhoChunk<T>, "density">
+>;
+
+//template<typename T, typename Desc>
+//using ParticleArray = Array<
+//	Particle<T,Desc::D>
+//>;
+}
+
+template<typename T, typename Desc>
+saw::error_or<void> setup_initial_conditions(
+		saw::data<sch::ChunkStruct<T,Desc>>& fields,
+		saw::data<sch::MacroStruct<T,Desc>>& macros,
+		saw::data<sch::FixedArray<sch::Particle<T,Desc::D>, particle_amount>>& particles
+){
+	auto& info_f = fields.template get<"info">();
+	// Set everything as walls
+	iterator<Desc::D>::apply(
+		[&](auto& index){
+			info_f.at(index).set(1u);
+		},
+		{},
+		info_f.get_dims(),
+		{}
+	);
+	// Fluid
+	iterator<Desc::D>::apply(
+		[&](auto& index){
+			info_f.at(index).set(2u);
+		},
+		{},
+		info_f.get_dims(),
+		{{1u,1u}}
+	);
+	
+	// Inflow
+	iterator<Desc::D>::apply(
+		[&](auto& index){
+			info_f.at(index).set(3u);
+		},
+		{{0u,0u}},
+		{{1u,dim_y}},
+		{{0u,1u}}
+	);
+	
+	// Outflow
+	iterator<Desc::D>::apply(
+		[&](auto& index){
+			info_f.at(index).set(4u);
+		},
+		{{dim_x-1u,0u}},
+		{{dim_x, dim_y}},
+		{{0u,1u}}
+	);
+	//
+	auto& df_f = fields.template get<"dfs_old">();
+	auto& rho_f = macros.template get<"density">();
+	auto& vel_f = macros.template get<"velocity">();
+	
+	iterator<Desc::D>::apply(
+		[&](auto& index){
+			auto& df = df_f.at(index);
+			auto& rho = rho_f.at(index);
+			rho.at({}) = {1};
+			auto& vel = vel_f.at(index);
+			auto eq = equilibrium<T,Desc>(rho,vel);
+
+			df = eq;
+		},
+		{},// 0-index
+		df_f.get_dims()
+	);
+
+	iterator<Desc::D>::apply(
+		[&](auto& index){
+			auto& df = df_f.at(index);
+			auto& rho = rho_f.at(index);
+			rho.at({}) = {1};
+			auto& vel = vel_f.at(index);
+			if(info_f.at(index).get() == 2u){
+				vel.at({{0u}}) = 0.0;
+			}
+			auto eq = equilibrium<T,Desc>(rho,vel);
+
+			df = eq;
+		},
+		{},// 0-index
+		df_f.get_dims(),
+		{{1u,1u}}
+	);
+	
+	iterator<Desc::D>::apply(
+		[&](auto& index){
+			saw::data<sch::Vector<T,Desc::D>> middle, ind_vec;
+			middle.at({{0u}}) = dim_x * 0.25;
+			middle.at({{1u}}) = dim_y * 0.5;
+
+			ind_vec.at({{0u}}) = index.at({{0u}}).template cast_to<T>();
+			ind_vec.at({{1u}}) = index.at({{1u}}).template cast_to<T>();
+
+			auto dist = middle - ind_vec;
+			auto dist_2 = saw::math::dot(dist,dist);
+			if(dist_2.at({}).get() < dim_y*dim_y*0.01){
+				info_f.at(index) = 1u;
+			}
+		},
+		{},// 0-index
+		df_f.get_dims()
+	);
+
+	return saw::make_void();
+}
+
+template<typename T, typename Desc>
+saw::error_or<void> step(
+		saw::data<sch::Ptr<sch::ChunkStruct<T,Desc>>,encode::Sycl<saw::encode::Native>>& fields,
+		saw::data<sch::Ptr<sch::MacroStruct<T,Desc>>,encode::Sycl<saw::encode::Native>>& macros,
+		saw::data<sch::FixedArray<sch::Particle<T,Desc::D>, particle_amount>>& particles,
+		saw::data<sch::UInt64> t_i,
+		device& dev
+){
+	auto& q = dev.get_handle();
+	auto& info_f = fields.template get<"info">();
+
+	{
+		auto& p = particles.at({{0u}});
+
+		auto& p_coll = p.template get<"collision">();
+		auto& p_rad = p_coll.template get<"radius">();
+	}
+
+
+	// auto coll_ev = 
+	q.submit([&](acpp::sycl::handler& h){
+		// Need nicer things to handle the flow. I see improvement here
+		component<T,Desc,cmpt::BGK, encode::Sycl<saw::encode::Native>> collision{0.65};
+		component<T,Desc,cmpt::BounceBack,encode::Sycl<saw::encode::Native>> bb;
+		component<T,Desc,cmpt::AntiBounceBack<0u>,encode::Sycl<saw::encode::Native>> abb;
+
+		saw::data<sch::Scalar<T>> rho_b;
+		rho_b.at({}) = 1.0;
+		saw::data<sch::Vector<T,Desc::D>> vel_b;
+		vel_b.at({{0u}}) = 0.015;
+
+		component<T,Desc,cmpt::Equilibrium,encode::Sycl<saw::encode::Native>> equi{rho_b,vel_b};
+
+		component<T,Desc,cmpt::ZouHeHorizontal<true>,encode::Sycl<saw::encode::Native>> flow_in{
+			[&](){
+				uint64_t target_t_i = 64u;
+				if(t_i.get() < target_t_i){
+					return 1.0 + (0.0015 / target_t_i) * t_i.get();
+				}
+				return 1.0015;
+			}()
+		};
+		component<T,Desc,cmpt::ZouHeHorizontal<false>,encode::Sycl<saw::encode::Native>> flow_out{1.0};
+
+
+		h.parallel_for(acpp::sycl::range<Desc::D>{dim_x,dim_y}, [=](acpp::sycl::id<Desc::D> idx){
+			saw::data<sch::FixedArray<sch::UInt64,Desc::D>> index;
+			for(uint64_t i = 0u; i < Desc::D; ++i){
+				index.at({{i}}).set(idx[i]);
+			}
+
+			auto info = info_f.at(index);
+			
+			switch(info.get()){
+				case 0u:
+				break;
+				case 1u:
+					abb.apply(fields,index,t_i);
+				break;
+				case 2u:
+					collision.apply(fields,macros,index,t_i);
+					break;
+				case 3u:
+					//flow_in.apply(fields,index,t_i);
+					equi.apply(fields,index,t_i);
+					collision.apply(fields,macros,index,t_i);
+					break;
+				case 4u:
+					// flow_out.apply(fields,index,t_i);
+					equi.apply(fields,index,t_i);
+					collision.apply(fields,macros,index,t_i);
+				break;
+				default:
+				break;
+			}
+		});
+	}).wait();
+
+	
+	// Step
+	/*
+	q.submit([&](acpp::sycl::handler& h){
+		// h.depends_on(collision_ev);
+	}).wait();
+	*/
+
+	return saw::make_void();
+}
+}
+}
+
+template<typename T, typename Desc>
+saw::error_or<void> lbm_main(int argc, char** argv){
+	using namespace kel::lbm;
+
+	using dfi = df_info<T,Desc>;
+
+	auto eo_lbm_dir = output_directory();
+	if(eo_lbm_dir.is_error()){
+		return std::move(eo_lbm_dir.get_error());
+	}
+	auto& lbm_dir = eo_lbm_dir.get_value();
+
+	auto out_dir = lbm_dir / "poiseulle_particles_2d_bgk_gpu";
+
+	{
+		std::error_code ec;
+		std::filesystem::create_directories(out_dir,ec);
+		if(ec != std::errc{}){
+			return saw::make_error<saw::err::critical>("Could not create output directory");
+		}
+	}
+
+	converter<T> conv {
+		// delta_x
+		{{1.0}},
+		// delta_t
+		{{1.0}}
+	};
+	
+	print_lbm_meta<T,Desc>(conv,{0.05},{0.01},{0.4 * dim_y});
+
+	// saw::data<sch::FixedArray<sch::UInt64,Desc::D>> meta{{dim_x,dim_y}};
+	auto lbm_data_ptr = saw::heap<saw::data<sch::ChunkStruct<T,Desc>>>();
+	auto lbm_macro_data_ptr = saw::heap<saw::data<sch::MacroStruct<T,Desc>>>();
+	auto lbm_particle_data_ptr = saw::heap<saw::data<sch::FixedArray<sch::Particle<T,Desc::D>, particle_amount>>>();
+	
+	std::cout<<"Estimated Bytes: "<<memory_estimate<sch::ChunkStruct<T,Desc>,sch::MacroStruct<T,Desc>>().get()<<std::endl;
+
+	auto eo_aio = saw::setup_async_io();
+	if(eo_aio.is_error()){
+		return std::move(eo_aio.get_error());
+	}
+	auto& aio = eo_aio.get_value();
+	saw::wait_scope wait{aio.event_loop};
+
+	bool krun = true;
+	bool print_status = false;
+	aio.event_port.on_signal(saw::Signal::Terminate).then([&](){
+		krun = false;
+	}).detach();
+	aio.event_port.on_signal(saw::Signal::User1).then([&](){
+		print_status = true;
+	}).detach();
+
+	device dev;
+
+	auto& sycl_q = dev.get_handle();
+
+	sycl_q.wait();
+	{
+		auto eov = setup_initial_conditions<T,Desc>(*lbm_data_ptr,*lbm_macro_data_ptr,*lbm_particle_data_ptr);
+		if(eov.is_error()){
+			return eov;
+		}
+	}
+	{
+		auto eov = write_vtk_file(out_dir,"initial_state",0u,*lbm_data_ptr);
+		if(eov.is_error()){
+			return eov;
+		}
+	}
+
+	saw::data<sch::ChunkStruct<T,Desc>, encode::Sycl<saw::encode::Native>> lbm_sycl_data{sycl_q};
+	saw::data<sch::MacroStruct<T,Desc>, encode::Sycl<saw::encode::Native>> lbm_sycl_macro_data{sycl_q};
+	saw::data<sch::FixedArray<sch::Particle<T,Desc::D>, particle_amount>, encode::Sycl<saw::encode::Native>> lbm_sycl_particle_data{sycl_q};
+	sycl_q.wait();
+
+	auto lsd_view = make_chunk_struct_view(lbm_sycl_data);
+	auto lsdm_view = make_chunk_struct_view(lbm_sycl_macro_data);
+	{
+		auto eov = dev.copy_to_device(*lbm_data_ptr,lbm_sycl_data);
+		if(eov.is_error()){
+			return eov;
+		}
+	}
+	{
+		auto eov = dev.copy_to_device(*lbm_macro_data_ptr,lbm_sycl_macro_data);
+		if(eov.is_error()){
+			return eov;
+		}
+	}
+	{
+		auto eov = dev.copy_to_device(*lbm_particle_data_ptr,lbm_sycl_particle_data);
+		if(eov.is_error()){
+			return eov;
+		}
+	}
+	sycl_q.wait();
+	saw::data<sch::UInt64> time_steps{16u*4096ul};
+
+	auto& info_f = lsd_view.template get<"info">();
+
+	for(saw::data<sch::UInt64> i{0u}; i < time_steps and krun; ++i){
+		// BC + Collision
+		{
+			auto eov = step<T,Desc>(lsd_view,lsdm_view,*lbm_particle_data_ptr,i,dev);
+			if(eov.is_error()){
+				return eov;
+			}
+		}
+		sycl_q.wait();
+		/*
+		{
+			{
+				auto eov = dev.copy_to_host(lbm_sycl_macro_data,*lbm_macro_data_ptr);
+				if(eov.is_error()){
+					return eov;
+				}
+			}
+			{
+				auto eov = write_vtk_file(out_dir,"m",i.get(), *lbm_macro_data_ptr);
+				if(eov.is_error()){
+					return eov;
+				}
+			}
+		}
+		*/
+		/*
+		{
+			{
+				auto eov = dev.copy_to_host(lbm_sycl_data,*lbm_data_ptr);
+				if(eov.is_error()){
+					return eov;
+				}
+			}
+			{
+				auto eov = write_csv_file(out_dir,"lbm",i.get(), *lbm_data_ptr);
+				if(eov.is_error()){
+					return eov;
+				}
+			}
+		}
+		*/
+		// Stream
+		sycl_q.submit([&](acpp::sycl::handler& h){
+			component<T,Desc,cmpt::Stream,encode::Sycl<saw::encode::Native>> stream;
+
+			h.parallel_for(acpp::sycl::range<Desc::D>{dim_x,dim_y}, [=](acpp::sycl::id<Desc::D> idx){
+				saw::data<sch::FixedArray<sch::UInt64,Desc::D>> index;
+				for(uint64_t i = 0u; i < Desc::D; ++i){
+					index.at({{i}}).set(idx[i]);
+				}
+				
+				auto info = info_f.at(index);
+				
+				if(info.get() > 0u){
+					stream.apply(lsd_view,index,i);
+				}
+			});
+		}).wait();
+		wait.poll();
+		if(print_status){
+			std::cout<<"Status: "<<i.get()<<" of "<<time_steps.get()<<" - "<<(i.template cast_to<sch::Float64>().get() * 100 / time_steps.get())<<"%"<<std::endl;
+			print_status = false;
+		}
+		print_progress_bar(i.get(), time_steps.get()-1u);
+	}
+
+	// After Loop
+	sycl_q.wait();
+	{
+		auto eov = dev.copy_to_host(lbm_sycl_macro_data,*lbm_macro_data_ptr);
+		if(eov.is_error()){
+			return eov;
+		}
+	}
+	{
+		auto eov = write_vtk_file(out_dir,"m",time_steps.get(), *lbm_macro_data_ptr);
+		if(eov.is_error()){
+			return eov;
+		}
+	}
+
+	sycl_q.wait();
+	return saw::make_void();
+}
+
+using FloatT = kel::lbm::sch::Float32;
+
+int main(int argc, char** argv){
+	auto eov = lbm_main<FloatT,kel::lbm::sch::D2Q9>(argc, argv);
+	if(eov.is_error()){
+		auto& err = eov.get_error();
+		std::cerr<<"[Error] "<<err.get_category();
+		auto err_msg = err.get_message();
+		if(err_msg.size() > 0u){
+			std::cerr<<" - "<<err_msg;
+		}
+		std::cerr<<std::endl;
+		return err.get_id();
+	}
+	return 0;
+}
diff --git a/lib/core/c++/boundary.hpp b/lib/core/c++/boundary.hpp
index adb473d..4dbbdf8 100644
--- a/lib/core/c++/boundary.hpp
+++ b/lib/core/c++/boundary.hpp
@@ -174,14 +174,13 @@ class component<FP, Descriptor, cmpt::ZouHeHorizontal<Dir>, Encode> final {
 private:
 	saw::data<FP> rho_setting_;
 public:
-	component(const saw::data<FP>& density_setting__):
-		rho_setting_{density_setting__}
+	component(const saw::data<FP>& rho_setting__):
+		rho_setting_{rho_setting__}
 	{}
 
 	template<typename CellFieldSchema>
 	void apply(const saw::data<CellFieldSchema, Encode>& field, saw::data<sch::FixedArray<sch::UInt64,Descriptor::D>> index, saw::data<sch::UInt64> time_step) const {
 		using dfi = df_info<FP,Descriptor>;
-		constexpr int known_dir = Dir ? 1 : -1;
 
 		bool is_even = ((time_step.get() % 2) == 0);
 
@@ -191,42 +190,33 @@ public:
 		auto& dfs_old_f = (is_even) ? field.template get<"dfs_old">() : field.template get<"dfs">();
 
 		auto& dfs_old = dfs_old_f.at(index);
-		/**
-		 * Sum all known DFs
-		 */
-		saw::data<FP> sum_df{0};
-		for(saw::data<sch::UInt64> k{0u}; k < saw::data<sch::UInt64>{Descriptor::Q}; ++k){
-			auto c_k = dfi::directions[k.get()];
-
-			if(c_k[0u]*known_dir <= 0){
-				sum_df += dfs_old.at({k});
-			}
-		}
-
-		/**
-		 * Get the sum of the unknown dfs and precalculate the direction
-		 */
-		auto sum_unknown_dfs = (rho_setting_ - sum_df) * saw::data<FP>{known_dir};
 
-		for(saw::data<sch::UInt64> k{0u}; k < saw::data<sch::UInt64>{Descriptor::Q}; ++k){
-			auto c_k = dfi::directions[k.get()];
-			if(c_k[0u]*known_dir < 0){
-				sum_unknown_dfs += dfs_old.at({k}) * c_k[0u];
+		auto rho_vel_x = [&]() -> saw::data<FP> {
+			if constexpr (Dir){
+				auto S = dfs_old.at({0u})
+					+ dfs_old.at({3u}) + dfs_old.at({4u})
+					+ (dfs_old.at({1u}) + dfs_old.at({5u}) + dfs_old.at({7u})) * 2u;
+				return rho_setting_ - S;
 			}
-		}
-
-		auto vel_x = sum_unknown_dfs / rho_setting_;
+			else if constexpr (not Dir) {
+				auto S = dfs_old.at({0u})
+					+ dfs_old.at({3u}) + dfs_old.at({4u})
+					+ (dfs_old.at({2u}) + dfs_old.at({6u}) + dfs_old.at({8u})) * 2u;
+				return S - rho_setting_;
+			}
+			return {};
+		}();
 
 		static_assert(Descriptor::D == 2u and Descriptor::Q == 9u, "Some parts are hard coded sadly");
 
 		if constexpr (Dir) {
-			dfs_old.at({2u}) = dfs_old.at({1u}) + saw::data<FP>{2.0 / 3.0} * rho_setting_ * vel_x;
-			dfs_old.at({6u}) = dfs_old.at({5u}) + saw::data<FP>{1.0 / 6.0} * rho_setting_ * vel_x + saw::data<FP>{0.5} * (dfs_old.at({4u}) - dfs_old.at({3u}));
-			dfs_old.at({8u}) = dfs_old.at({7u}) + saw::data<FP>{1.0 / 6.0} * rho_setting_ * vel_x + saw::data<FP>{0.5} * (dfs_old.at({3u}) - dfs_old.at({4u}));
+			dfs_old.at({2u}) = dfs_old.at({1u}) + saw::data<FP>{2.0 / 3.0} * rho_vel_x;
+			dfs_old.at({6u}) = dfs_old.at({5u}) + saw::data<FP>{1.0 / 6.0} * rho_vel_x + saw::data<FP>{0.5} * (dfs_old.at({4u}) - dfs_old.at({3u}));
+			dfs_old.at({8u}) = dfs_old.at({7u}) + saw::data<FP>{1.0 / 6.0} * rho_vel_x + saw::data<FP>{0.5} * (dfs_old.at({3u}) - dfs_old.at({4u}));
 		}else if constexpr (not Dir){
-			dfs_old.at({1u}) = dfs_old.at({2u}) - saw::data<FP>{2.0 / 3.0} * rho_setting_ * vel_x;
-			dfs_old.at({5u}) = dfs_old.at({6u}) - saw::data<FP>{1.0 / 6.0} * rho_setting_ * vel_x + saw::data<FP>{0.5} * (dfs_old.at({3u}) - dfs_old.at({4u}));
-			dfs_old.at({7u}) = dfs_old.at({8u}) - saw::data<FP>{1.0 / 6.0} * rho_setting_ * vel_x + saw::data<FP>{0.5} * (dfs_old.at({4u}) - dfs_old.at({3u}));
+			dfs_old.at({1u}) = dfs_old.at({2u}) - saw::data<FP>{2.0 / 3.0} * rho_vel_x;
+			dfs_old.at({5u}) = dfs_old.at({6u}) - saw::data<FP>{1.0 / 6.0} * rho_vel_x + saw::data<FP>{0.5} * (dfs_old.at({3u}) - dfs_old.at({4u}));
+			dfs_old.at({7u}) = dfs_old.at({8u}) - saw::data<FP>{1.0 / 6.0} * rho_vel_x + saw::data<FP>{0.5} * (dfs_old.at({4u}) - dfs_old.at({3u}));
 		}
 	}
 };
diff --git a/lib/core/c++/descriptor.hpp b/lib/core/c++/descriptor.hpp
index 73f0cce..9f7399a 100644
--- a/lib/core/c++/descriptor.hpp
+++ b/lib/core/c++/descriptor.hpp
@@ -146,15 +146,15 @@ public:
 	static constexpr uint64_t Q = 9u;
 
 	static constexpr std::array<std::array<int32_t, D>, Q> directions = {{
-		{ 0, 0},
-		{-1, 0},
-		{ 1, 0},
-		{ 0,-1},
-		{ 0, 1},
-		{-1,-1},
-		{ 1, 1},
-		{-1, 1},
-		{ 1,-1}
+		{ 0, 0}, // 0
+		{-1, 0}, // 1
+		{ 1, 0}, // 2
+		{ 0,-1}, // 3
+		{ 0, 1}, // 4
+		{-1,-1}, // 5
+		{ 1, 1}, // 6
+		{-1, 1}, // 7
+		{ 1,-1}  // 8
 	}};
 
 	static constexpr std::array<typename saw::native_data_type<T>::type,Q> weights = {
diff --git a/lib/core/c++/math/n_linear.hpp b/lib/core/c++/math/n_linear.hpp
index 62906cd..8fb0600 100644
--- a/lib/core/c++/math/n_linear.hpp
+++ b/lib/core/c++/math/n_linear.hpp
@@ -1,29 +1,136 @@
 #pragma once
 
 #include "../common.hpp"
+#include "../iterator.hpp"
 
 namespace kel {
 namespace lbm {
+namespace impl {
+template<typename FieldSchema, typename T, uint64_t D>
+struct n_linear_interpolate_helper final {
+	template<uint64_t i = 0u>
+	auto apply(const saw::data<FieldSchema>& field, const saw::data<sch::Vector<T,D>>& pos){
+		return pos;
+	}
+};
+}
+
+template<typename T, uint64_t D>
+saw::data<sch::Tuple<sch::Vector<sch::UInt64,D>,sch::Vector<T,D>>> position_to_index_and_fraction(const saw::data<sch::Vector<T,D>>& pos){
+	saw::data<sch::Tuple<sch::Vector<sch::UInt64,D>,sch::Vector<T,D>>> sep;
+
+	auto& ind = sep.template get<0u>();
+	auto& frac = sep.template get<1u>();
+
+	auto pos_cpy = pos;
+	// Guarantee that the pos is at least 0
+	for(uint64_t i = 0u; i < D; ++i){
+		pos_cpy.at({{i}}).set(std::max(pos.at({{i}}).get(), static_cast<typename saw::native_data_type<T>::type>(0)));
+	}
+
+	// Now we can cast to uint64_t
+	for(uint64_t i = 0u; i < D; ++i){
+		ind.at({{i}}) = pos_cpy.at({{i}}).template cast_to<sch::UInt64>();
+	}
+
+	frac = pos_cpy - ind.template cast_to<T>();
+
+	return sep;
+}
+
+template<typename T, uint64_t D>
+auto floor_index_from_position(const saw::data<sch::Vector<T,D>>& pos){
+	return position_to_index_and_fraction(pos).template get<0u>();
+}
+
+template<typename T, uint64_t D>
+saw::data<sch::Tuple<sch::Vector<sch::UInt64,D>,sch::Vector<T,D>>> position_to_index_and_fraction_bounded(
+	const saw::data<sch::Vector<T,D>>& pos,
+	const saw::data<sch::Vector<sch::UInt64,D>>& bound)
+{
+	auto infr = position_to_index_and_fraction(pos);
+	auto& ind = infr.template get<0u>();
+	auto& fra = infr.template get<1u>();
+	for(uint64_t i = 0u; i < D; ++i){
+		// If index is higher than bound. Set to bound and reset fraction
+		if((ind.at({{i}}).get()+1u) >= bound.at({{i}}).get()){
+			ind.at({{i}}).set(bound.at({{i}}).get()-1u);
+			fra.at({{i}}) = {};
+		}
+	}
+	return infr;
+}
+
 
 template<typename FieldSchema, typename T, uint64_t D>
-void n_linear_interpolate(const saw::data<FieldSchema>& field, const saw::data<sch::FixedArray<T,D>>& pos){
+auto n_linear_interpolate(
+		const saw::data<FieldSchema>& field, const saw::data<sch::Vector<T,D>>& pos){
 
+	// Pos
 	auto pos_bound = pos;
+	
+	// Dimensions
 	auto meta = field.dims();
-	saw::data<sch::UInt64> ind;
+
+	// Lower Index
+	saw::data<sch::FixedArray<sch::UInt64,D>> ind;
+
 	for(saw::data<sch::UInt64> i{0u}; i < saw::data<sch::UInt64>{D}; ++i){
-		pos_bound.at(i).set(
-			std::max(
-				std::min(
-					meta.at(i).template cast_to<T>().get(),
-					pos.at(i).get() + 1.5
-				),
-				1,
-			)
-			-1
-		);
-		ind.at(i) = pos_bound.at(i).template cast_to<sch::UInt64>();
+		// Native Positive i
+		auto npos_i = pos.at({i}).get();
+
+		{
+			// Ok I want to stay in bounds
+			npos_i = std::min(npos_i,meta.at(i).get()-1.0);
+			npos_i = std::max(npos_i,1.0);
+		}
+
+		// Native Index i
+		auto nind_i = static_cast<uint64_t>(std::floor(npos_i))-1ul;
+
+		// Set index to i
+		ind.at(i).set(nind_i);
+	}
+	saw::data<sch::Vector<T,D>> pos_frac;
+	for(saw::data<sch::UInt64> i{0u}; i < saw::data<sch::UInt64>{D}; ++i){
+		pos_frac.at({i}) = pos_bound.at({i}) - ind.at(i).template cast_to<T>();
+	}
+
+	// Base value
+	saw::data<typename FieldSchema::ValueType> res;
+
+	// constexpr uint64_t d_corners = 1ul << D;
+
+	saw::data<sch::FixedArray<sch::UInt64,D>> ones_ind;
+	for(saw::data<sch::UInt64> i{0u}; i < saw::data<sch::UInt64>{D}; ++i){
+		ones_ind.at({i}).set(1u);
+	}
+
+	iterator<D>::apply([&](auto ind){
+		// Iterates over (0,0,0) to (1,1,1)
+		saw::data<T> weight{1.0};
+
+		for(saw::data<sch::UInt64> d{0u}; d < saw::data<sch::UInt64>{D}; ++d){
+
+			saw::data<T> t = pos_frac.at({d});
+
+			if(ind.at(d).get() == 0u){
+				weight = weight * (saw::data<T>{1} - t);
+			}else{
+				weight = weight * t;
+			}
+		}
+
+	}, {}, ones_ind);
+}
+
+template<typename FieldSchema, typename T>
+saw::data<sch::Vector<T,2u>> bilinear_interpolate(const saw::data<FieldSchema>& field, const saw::data<sch::Vector<T,2u>>& pos){
+	saw::data<sch::Vector<T,2u>> res;
+
+	{
 	}
+	return {};
 }
 }
 }
diff --git a/lib/core/c++/particle/geometry/cube.hpp b/lib/core/c++/particle/geometry/cube.hpp
new file mode 100644
index 0000000..6392de8
--- /dev/null
+++ b/lib/core/c++/particle/geometry/cube.hpp
@@ -0,0 +1,22 @@
+#pragma once
+
+#include "../particle.hpp"
+
+namespace kel {
+namespace lbm {
+template<typename T, uint64_t D>
+class particle_cubic_geometry {
+private:
+public:
+	template<typename MT = T>
+	saw::data<sch::ParticleMask<MT,D>> generate_mask(uint64_t resolution, uint64_t bound_nodes = 0u){
+
+		saw::data<sch::ParticleMask<MT,D>> mask;
+
+		auto& grid = mask.template get<"grid">();
+		auto& com = mask.template get<"center_of_mass">();
+
+
+	}
+}
+}
diff --git a/lib/core/tests/math.cpp b/lib/core/tests/math.cpp
new file mode 100644
index 0000000..d456ce8
--- /dev/null
+++ b/lib/core/tests/math.cpp
@@ -0,0 +1,79 @@
+#include <forstio/test/suite.hpp>
+
+#include <iostream>
+#include "../c++/math/n_linear.hpp"
+
+namespace {
+namespace sch {
+using namespace saw::schema;
+}
+
+SAW_TEST("Math 1-Linear"){
+	using namespace kel;
+	
+	saw::data<sch::FixedArray<sch::Vector<sch::Float64,1u>,2u>> field;
+	{
+		field.at({{0u}}).at({{0u}}).set(-1.0);
+		field.at({{1u}}).at({{0u}}).set(2.0);
+	}
+	saw::data<sch::Vector<sch::Float64,1u>> pos;
+	pos.at({{0u}}).set(0.3);
+}
+
+SAW_TEST("Math/Floor Index and Fraction from Position"){
+	using namespace kel;
+
+	saw::data<sch::Vector<sch::Float64,2u>> pos;
+
+	{
+		pos.at({{0u}}) = 43.999;
+		pos.at({{1u}}) = -50.0;
+	}
+
+	auto ind_frac = lbm::position_to_index_and_fraction(pos);
+	auto& ind = ind_frac.template get<0u>();
+	for(uint64_t i = 0u; i < 2u; ++i){
+		std::cout<<ind.at({{i}}).get()<<" ";
+	}
+	std::cout<<std::endl;
+	auto& frac = ind_frac.template get<1u>();
+	for(uint64_t i = 0u; i < 2u; ++i){
+		std::cout<<frac.at({{i}}).get()<<" ";
+	}
+	std::cout<<std::endl;
+
+	SAW_EXPECT(true, "Default true check");
+}
+
+SAW_TEST("Math/Floor Index and Fraction from Position and Bounded"){
+	using namespace kel;
+
+	saw::data<sch::Vector<sch::Float64,2u>> pos;
+
+	{
+		pos.at({{0u}}) = 43.999;
+		pos.at({{1u}}) = -50.0;
+	}
+
+	saw::data<sch::Vector<sch::UInt64,2U>> bound;
+	{
+		bound.at({{0u}}) = 32u;
+		bound.at({{1u}}) = 16u;
+	}
+
+	auto ind_frac = lbm::position_to_index_and_fraction_bounded(pos,bound);
+	auto& ind = ind_frac.template get<0u>();
+	for(uint64_t i = 0u; i < 2u; ++i){
+		std::cout<<ind.at({{i}}).get()<<" ";
+	}
+	std::cout<<std::endl;
+	auto& frac = ind_frac.template get<1u>();
+	for(uint64_t i = 0u; i < 2u; ++i){
+		std::cout<<frac.at({{i}}).get()<<" ";
+	}
+	std::cout<<std::endl;
+
+	SAW_EXPECT(true, "Default true check");
+}
+
+}