1 files changed, 256 insertions, 0 deletions
diff --git a/modules/core/c++/write_vtk.hpp b/modules/core/c++/write_vtk.hpp
new file mode 100644
index 0000000..e852172
--- /dev/null
+++ b/modules/core/c++/write_vtk.hpp
@@ -0,0 +1,256 @@
+#pragma once
+
+#include <forstio/error.hpp>
+
+#include <forstio/codec/data.hpp>
+#include <forstio/codec/data_math.hpp>
+
+#include "descriptor.hpp"
+#include "flatten.hpp"
+#include "chunk.hpp"
+
+#include <fstream>
+#include <filesystem>
+
+namespace kel {
+namespace lbm {
+namespace impl {
+
+template<typename CellFieldSchema>
+struct lbm_vtk_writer {
+};
+
+template<typename T, uint64_t D>
+struct lbm_vtk_writer<sch::Primitive<T,D>> {
+	static saw::error_or<void> apply_header(std::ostream& vtk_file, std::string_view name){
+		vtk_file<<"SCALARS "<<name<<" float 1\n";
+		vtk_file<<"LOOKUP_TABLE default\n";
+		return saw::make_void();
+	}
+	static saw::error_or<void> apply(std::ostream& vtk_file, const saw::data<sch::Primitive<T,D>>& field){
+		if constexpr (std::is_same_v<T,sch::UnsignedInteger> and D == 1u) {
+			vtk_file<<field.template cast_to<sch::UInt16>().get()<<"\n";
+		}else{
+			vtk_file<<field.get()<<"\n";
+		}
+		return saw::make_void();
+	}
+};
+
+template<typename T, uint64_t D>
+struct lbm_vtk_writer<sch::FixedArray<T,D>> {
+	static saw::error_or<void> apply_header(std::ostream& vtk_file, std::string_view name){
+		vtk_file<<"VECTORS "<<name<<" float\n";
+		return saw::make_void();
+	}
+
+	static saw::error_or<void> apply(std::ostream& vtk_file, const saw::data<sch::FixedArray<T,D>>& field){
+		saw::data<sch::FixedArray<sch::UInt64,D>> index;
+		for(saw::data<sch::UInt64> it{0}; it.get() < D; ++it){
+			index.at({0u}).set(0u);
+		}
+
+		// vtk_file<<"VECTORS "<<name<<" float\n";
+		for(uint64_t i = 0u; i < D; ++i){
+			if(i > 0){
+				vtk_file<<" ";
+			}
+			vtk_file<<field.at({i}).get();
+		}
+		for(uint64_t i = D; i < 3; ++i){
+			vtk_file<<" 0";
+		}
+		vtk_file<<"\n";
+		return saw::make_void();
+	}
+};
+
+template<typename T, uint64_t Ghost, uint64_t... D>
+struct lbm_vtk_writer<sch::Chunk<T,Ghost,D...>> {
+
+	template<uint64_t d>
+	static saw::error_or<void> apply_d(std::ostream& vtk_file, const saw::data<sch::Chunk<T,Ghost,D...>>& field, saw::data<sch::FixedArray<sch::UInt64,sizeof...(D)>>& index){
+		// VTK wants to iterate over z,y,x instead of x,y,z
+		// We could reorder the dimensions, but eh
+		if constexpr ( d > 0u){
+			for(index.at({d-1u}) = 0u; index.at({d-1u}) < field.get_dims().at({d-1u}); ++index.at({d-1u})){
+				auto eov = apply_d<d-1u>(vtk_file, field, index);
+			}
+		}else{
+			auto eov = lbm_vtk_writer<T>::apply(vtk_file, field.at(index));
+			if(eov.is_error()) return eov;
+		}
+		return saw::make_void();
+	}
+
+	static saw::error_or<void> apply(std::ostream& vtk_file, const saw::data<sch::Chunk<T,Ghost,D...>>& field, std::string_view name){
+		{
+			auto eov = lbm_vtk_writer<T>::apply_header(vtk_file,name);
+			if(eov.is_error()){
+				return eov;
+			}
+		}
+		saw::data<sch::FixedArray<sch::UInt64,sizeof...(D)>> index;
+		for(saw::data<sch::UInt64> it{0}; it.get() < sizeof...(D); ++it){
+			index.at({0u}).set(0u);
+		}
+
+		{
+			auto eov = apply_d<sizeof...(D)>(vtk_file, field, index);
+			if(eov.is_error()){
+				return eov;
+			}
+		}
+
+		vtk_file<<"\n";
+
+		return saw::make_void();
+	}
+};
+
+template<typename T, uint64_t D>
+struct lbm_vtk_writer<sch::Vector<T,D>> {
+	static saw::error_or<void> apply_header(std::ostream& vtk_file, std::string_view name){
+		vtk_file<<"VECTORS "<<name<<" float\n";
+		return saw::make_void();
+	}
+	static saw::error_or<void> apply(std::ostream& vtk_file, const saw::data<sch::Vector<T,D>>& field){
+		static_assert(D > 0, "Non-dimensionality is bad for velocity.");
+		static_assert(D <= 3, "4th dimension as well. Mostly due to vtk.");
+
+		// vtk_file<<"VECTORS "<<name<<" float\n";
+		for(uint64_t i = 0u; i < D; ++i){
+			if(i > 0){
+				vtk_file<<" ";
+			}
+			vtk_file<<field.at({{i}}).get();
+		}
+		for(uint64_t i = D; i < 3; ++i){
+			vtk_file<<" 0";
+		}
+		vtk_file<<"\n";
+		return saw::make_void();
+	}
+};
+
+template<typename T>
+struct lbm_vtk_writer<sch::Scalar<T>> {
+	static saw::error_or<void> apply_header(std::ostream& vtk_file, std::string_view name){
+		vtk_file<<"SCALARS "<<name<<" float 1\n";
+		vtk_file<<"LOOKUP_TABLE default\n";
+		return saw::make_void();
+	}
+	static saw::error_or<void> apply(std::ostream& vtk_file, const saw::data<sch::Scalar<T>>& field){
+		// vtk_file<<"VECTORS "<<name<<" float\n";
+		vtk_file<<field.at({}).get();
+		vtk_file<<"\n";
+		return saw::make_void();
+	}
+};
+
+template<typename... MemberT, saw::string_literal... Keys, uint64_t... Ghost, uint64_t... Dims>
+struct lbm_vtk_writer<sch::Struct<sch::Member<sch::Chunk<MemberT,Ghost,Dims...>,Keys>...>> final  {
+	template<uint64_t i>
+	static saw::error_or<void> iterate_i(std::ostream& vtk_file,
+		const saw::data<sch::Struct<sch::Member<sch::Chunk<MemberT,Ghost,Dims...>,Keys>...>>& field){
+
+		if constexpr ( i < sizeof...(MemberT) ) {
+			using MT = typename saw::parameter_pack_type<i,sch::Member<sch::Chunk<MemberT,Ghost,Dims...>,Keys>...>::type;
+			{
+				auto eov = lbm_vtk_writer<typename MT::ValueType>::apply(vtk_file,field.template get<MT::KeyLiteral>(), MT::KeyLiteral.view());
+				if(eov.is_error()){
+					return eov;
+				}
+			}
+
+			return iterate_i<i+1u>(vtk_file, field);
+		}
+
+		return saw::make_void();
+	}
+
+
+	static saw::error_or<void> apply(std::ostream& vtk_file,
+		const saw::data<sch::Struct<sch::Member<sch::Chunk<MemberT,Ghost,Dims...>,Keys>...>>& field){
+		
+		vtk_file
+			<<"# vtk DataFile Version 3.0\n"
+			<<"LBM File\n"
+			<<"ASCII\n"
+			<<"DATASET STRUCTURED_POINTS\n"
+			<<"SPACING 1.0 1.0 1.0\n"
+			<<"ORIGIN 0.0 0.0 0.0\n"
+		;
+
+		auto& field_0 = field.template get<saw::parameter_key_pack_type<0u,Keys...>::literal>();	
+		auto meta = field_0.get_dims();
+		
+		saw::data<sch::UInt64> pd_size{1u};
+		// DIMENSIONS
+
+		{
+			vtk_file << "DIMENSIONS";
+			pd_size.set(saw::ct_multiply<uint64_t,Dims...>::value);
+			
+			static_assert(saw::ct_multiply<uint64_t,Dims...>::value > 0u, "Invalid Dim size resulting in length 0u");
+
+			for(saw::data<sch::UInt64> i{0u}; i.get() < sizeof...(Dims); ++i){
+				vtk_file << " " << meta.at(i).get(); 
+			}
+			for(saw::data<sch::UInt64> i{sizeof...(Dims)}; i.get() < 3u; ++i){
+				vtk_file << " 1";
+			}
+
+			vtk_file << "\n";
+		}
+		if constexpr (sizeof...(MemberT) > 0u){
+			// POINT DATA
+			{
+				vtk_file << "\nPOINT_DATA " << pd_size.get() <<"\n";
+			}
+
+			// HEADER TO BODY
+			{
+				vtk_file << "\n";
+			}
+		}
+		
+		return iterate_i<0u>(vtk_file, field);
+	}
+};
+
+}
+
+template<typename Sch>
+saw::error_or<void> write_vtk_file(const std::filesystem::path& out_dir, const std::string_view& file_name, uint64_t d_t, const saw::data<Sch>& field){
+
+	auto vtk_dir = out_dir / "vtk";
+	{
+		std::error_code ec;
+		std::filesystem::create_directories(vtk_dir,ec);
+		if(ec != std::errc{}){
+			return saw::make_error<saw::err::critical>("Could not create directory for write_vtk_file function");
+		}
+	}
+	std::string ft_name{file_name};
+
+	std::stringstream sstr;
+	sstr
+		<<file_name
+		<<"_"
+		<<d_t
+		<<".vtk"
+	;
+
+	std::ofstream vtk_file{vtk_dir / sstr.str() };
+
+	if( not vtk_file.is_open() ){
+		return saw::make_error<saw::err::critical>("Could not open file.");
+	}
+
+	auto eov = impl::lbm_vtk_writer<Sch>::apply(vtk_file, field);
+	return eov;
+}
+
+}
+}