From e720bbf4ead889a607a11513c4a64cc3ccb3e691 Mon Sep 17 00:00:00 2001
From: Adrian Kummerlaender
Date: Wed, 10 Oct 2018 22:46:12 +0200
Subject: Improve build instructions

---
 CMakeLists.txt      | 43 ++++++++++++++++++++++++++++++-------------
 shell.nix           |  4 ++--
 src/fluid_buffer.cc |  4 +++-
 src/fluid_buffer.h  |  3 ++-
 4 files changed, 37 insertions(+), 17 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index e5cbd03..29ad827 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,31 +1,48 @@
 cmake_minimum_required(VERSION 3.10)
-project(boltzbub)
+project(boltzbub LANGUAGES CXX)
 
-set(
-	CMAKE_CXX_FLAGS
-	"${CMAKE_CXX_FLAGS} -std=c++1z -W -Wall -Wextra -Winline -pedantic"
+add_library(
+	boltzbub
+		src/lbm.cc
+		src/fluid_buffer.cc
+		src/boundary_conditions.cc
 )
 
-include_directories(
-	src/
+target_compile_features(
+	boltzbub
+	PUBLIC
+		cxx_std_17
 )
 
-set(
-	BASE
-	src/lbm.cc
-	src/fluid_buffer.cc
-	src/boundary_conditions.cc
+target_include_directories(
+	boltzbub
+	PUBLIC
+		${CMAKE_CURRENT_SOURCE_DIR}/src
+)
+
+target_link_libraries(
+	boltzbub
+	PRIVATE
+		stdc++fs
 )
 
 add_executable(
 	cavity2d
 		cavity2d.cc
-		${BASE}
+)
+
+target_link_libraries(
+	cavity2d
+		boltzbub
 )
 
 add_executable(
 	cavity2d_with_obstacles
 		cavity2d_with_obstacles.cc
-		${BASE}
 		src/box_obstacle.cc
 )
+
+target_link_libraries(
+	cavity2d_with_obstacles
+		boltzbub
+)
diff --git a/shell.nix b/shell.nix
index 087712a..dabe8b5 100644
--- a/shell.nix
+++ b/shell.nix
@@ -1,12 +1,12 @@
 with import <nixpkgs> {};
 
-stdenv.mkDerivation rec {
+stdenvNoCC.mkDerivation rec {
   name = "boltzbub-env";
   env = buildEnv { name = name; paths = buildInputs; };
 
   buildInputs = [
     git
-    gcc
+    gcc8
     cmake
   ];
 
diff --git a/src/fluid_buffer.cc b/src/fluid_buffer.cc
index 1f40d2f..9291fdd 100644
--- a/src/fluid_buffer.cc
+++ b/src/fluid_buffer.cc
@@ -32,7 +32,9 @@ Velocity& FluidBuffer::velocity(Vector<std::size_t> pos) {
 	return velocity(pos[0], pos[1]);
 }
 
-void FluidBuffer::writeAsVTK(const std::string& path) {
+void FluidBuffer::writeAsVTK(const std::filesystem::path& path) {
+	std::filesystem::create_directories(path.parent_path());
+
 	std::ofstream fout;
 	fout.open(path.c_str());
 
diff --git a/src/fluid_buffer.h b/src/fluid_buffer.h
index 72518bb..b0e0936 100644
--- a/src/fluid_buffer.h
+++ b/src/fluid_buffer.h
@@ -2,6 +2,7 @@
 
 #include <memory>
 #include <string>
+#include <filesystem>
 
 #include "vector.h"
 
@@ -28,5 +29,5 @@ public:
 	Velocity& velocity(std::size_t x, std::size_t y);
 	Velocity& velocity(Vector<std::size_t> pos);
 
-	void writeAsVTK(const std::string& path);
+	void writeAsVTK(const std::filesystem::path& path);
 };
-- 
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