From 24bf28a8fb9cc8c3a90b77de9b60728bece7885d Mon Sep 17 00:00:00 2001
From: "Claudius \"keldu\" Holeksa" <mail@keldu.de>
Date: Sat, 18 Oct 2025 18:01:14 +0200
Subject: Moving project structure for more less compilation

---
 lib/c++/write_vtk.hpp | 205 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 205 insertions(+)
 create mode 100644 lib/c++/write_vtk.hpp

(limited to 'lib/c++/write_vtk.hpp')

diff --git a/lib/c++/write_vtk.hpp b/lib/c++/write_vtk.hpp
new file mode 100644
index 0000000..0647db5
--- /dev/null
+++ b/lib/c++/write_vtk.hpp
@@ -0,0 +1,205 @@
+#pragma once
+
+#include <forstio/error.hpp>
+
+#include <forstio/codec/data.hpp>
+#include <forstio/codec/data_math.hpp>
+
+#include "descriptor.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\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){
+		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){
+		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, 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<uint64_t Dim, typename... StructT, saw::string_literal... StructN>
+struct lbm_vtk_writer<sch::Array<sch::Struct<sch::Member<StructT,StructN>...> , Dim>> {
+
+	template<uint64_t i, uint64_t Dep>
+	static saw::error_or<void> write_i_iterate_d(std::ostream& vtk_file, const saw::data<sch::Array<sch::Struct<sch::Member<StructT,StructN>...>,Dim>>& field, saw::data<sch::FixedArray<sch::UInt64,Dim>>& index){
+		constexpr auto Lit = saw::parameter_key_pack_type<i, StructN...>::literal;
+		using Type = typename saw::parameter_pack_type<i,StructT...>::type;
+
+		if constexpr (Dep == 0u){
+			return lbm_vtk_writer<Type>::apply(vtk_file, field.at(index).template get<Lit>());
+		} else {
+			// Dep < Dim // I hope
+			static_assert(Dep > 0u, "Don't fall into this case");
+			for(index.at({Dep-1u}) = 0; index.at({Dep-1u}) < field.get_dims().at({Dep-1u}); ++index.at({Dep-1u})){
+				auto eov = write_i_iterate_d<i,Dep-1u>(vtk_file, field, index);
+				if(eov.is_error()){
+					return eov;
+				}
+			}
+		}
+		return saw::make_void();
+	}
+
+	template<uint64_t i>
+	static saw::error_or<void> write_i(std::ostream& vtk_file, const saw::data<sch::Array<sch::Struct<sch::Member<StructT,StructN>...>,Dim>>& field){
+
+		// auto meta = field.get_dims();
+		saw::data<sch::FixedArray<sch::UInt64,Dim>> index;
+		for(saw::data<sch::UInt64> it{0}; it.get() < Dim; ++it){
+			index.at({0u}).set(0u);
+		}
+		// vtk_file write?
+		// Data header
+		{
+
+			auto eov = lbm_vtk_writer<typename saw::parameter_pack_type<i,StructT...>::type>::apply_header(vtk_file, saw::parameter_key_pack_type<i, StructN...>::literal.view());
+			if(eov.is_error()){
+				return eov;
+			}
+
+		}
+		return write_i_iterate_d<i,Dim>(vtk_file, field, index);
+	}
+
+	template<uint64_t i>
+	static saw::error_or<void> iterate_i(std::ostream& vtk_file, const saw::data<sch::Array<sch::Struct<sch::Member<StructT,StructN>...>, Dim>>& field){
+		// constexpr auto Lit = saw::parameter_key_pack_type<i, StructN...>::literal;
+		{
+			auto eov = write_i<i>(vtk_file, field);
+			if(eov.is_error()){
+				return eov;
+			}
+		}
+		if constexpr ( (i+1u) < sizeof...(StructT) ){
+			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::Array<sch::Struct<sch::Member<StructT,StructN>...>, Dim>>& 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 meta = field.get_dims();
+		saw::data<sch::UInt64> pd_size{1u};
+		// DIMENSIONS
+
+		{
+			vtk_file << "DIMENSIONS";
+			for(saw::data<sch::UInt64> i{0u}; i.get() < Dim; ++i){
+				pd_size = pd_size * meta.at(i);
+				vtk_file << " " << meta.at(i).get(); 
+			}
+			for(saw::data<sch::UInt64> i{Dim}; i.get() < 3u; ++i){
+				vtk_file << " 1";
+			}
+
+			vtk_file << "\n";
+		}
+
+		if constexpr (sizeof...(StructT) > 0u){
+			// POINT DATA
+			{
+				vtk_file << "POINT_DATA " << pd_size.get() <<"\n";
+			}
+
+			// HEADER TO BODY
+			{
+				vtk_file << "\n";
+			}
+
+			return iterate_i<0u>(vtk_file, field);
+		}
+
+		return saw::make_void();
+	}
+};
+}
+
+template<typename Struct>
+saw::error_or<void> write_vtk_file(const std::filesystem::path& file_name, const saw::data<Struct>& field){
+
+	std::ofstream vtk_file{file_name};
+
+	if(!vtk_file.is_open()){
+		return saw::make_error<saw::err::critical>("Could not open file.");
+	}
+
+
+	auto eov = impl::lbm_vtk_writer<Struct>::apply(vtk_file, field);
+	return eov;
+}
+}
+}
-- 
cgit v1.2.3