From be2164a504bf8f825d7a76af9504633adcf2596f Mon Sep 17 00:00:00 2001
From: "Claudius \"keldu\" Holeksa" <mail@keldu.de>
Date: Sat, 31 Jan 2026 17:23:03 +0100
Subject: Adding vtk writing

---
 examples/poiseulle_particles_2d_gpu/sim.cpp | 15 +++++++++++++++
 lib/core/c++/write_vtk.hpp                  | 12 ++++++++----
 lib/sycl/c++/data.hpp                       |  2 +-
 3 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/examples/poiseulle_particles_2d_gpu/sim.cpp b/examples/poiseulle_particles_2d_gpu/sim.cpp
index 255aa6d..3f3a584 100644
--- a/examples/poiseulle_particles_2d_gpu/sim.cpp
+++ b/examples/poiseulle_particles_2d_gpu/sim.cpp
@@ -210,6 +210,21 @@ saw::error_or<void> lbm_main(int argc, char** argv){
 				return eov;
 			}
 		}
+		{
+			auto eov = dev.copy_to_host(lbm_sycl_data,*lbm_data_ptr);
+			if(eov.is_error()){
+				return eov;
+			}
+		}
+		{
+			std::string file_name = "t_";
+			file_name += std::to_string(i.get());
+			file_name += ".vtk";
+			auto eov = write_vtk_file(file_name, *lbm_data_ptr);
+			if(eov.is_error()){
+				return eov;
+			}
+		}
 	}
 	sycl_q.wait();
 
diff --git a/lib/core/c++/write_vtk.hpp b/lib/core/c++/write_vtk.hpp
index 7d42bc9..204bb87 100644
--- a/lib/core/c++/write_vtk.hpp
+++ b/lib/core/c++/write_vtk.hpp
@@ -32,15 +32,13 @@ struct lbm_vtk_writer<sch::Primitive<T,D>> {
 	}
 };
 
-template<typename T, uint64_t D>
+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.");
+	static saw::error_or<void> apply(std::ostream& vtk_file, const saw::data<sch::FixedArray<T,D...>>& field){
 
 		// vtk_file<<"VECTORS "<<name<<" float\n";
 		for(uint64_t i = 0u; i < D; ++i){
@@ -82,6 +80,12 @@ struct lbm_vtk_writer<sch::Vector<T,D>> {
 	}
 };
 
+template<typename... Members>
+struct lbm_vtk_writer<sch::Struct<Members...>> final  {
+	template<uint64_t i>
+	lbm_vtk_writer<s
+};
+
 template<uint64_t Dim, typename... StructT, saw::string_literal... StructN>
 struct lbm_vtk_writer<sch::Array<sch::Struct<sch::Member<StructT,StructN>...> , Dim>> {
 
diff --git a/lib/sycl/c++/data.hpp b/lib/sycl/c++/data.hpp
index 75112fb..5155a53 100644
--- a/lib/sycl/c++/data.hpp
+++ b/lib/sycl/c++/data.hpp
@@ -338,7 +338,7 @@ struct sycl_copy_helper<sch::Struct<Members...>, Encode> final {
 	}
 	
 
-	static saw::error_or<void> copy_to_host(saw::data<Schema,Encode>& sycl_data, saw::data<Schema,encode::Sycl<Encode>>& host_data, sycl::queue& q){
+	static saw::error_or<void> copy_to_host(saw::data<Schema,encode::Sycl<Encode>>& sycl_data, saw::data<Schema,Encode>& host_data, sycl::queue& q){
 		return copy_to_host_member<0u>(sycl_data, host_data, q);
 	}
 };
-- 
cgit v1.2.3