From 27c4a848371bb58242e1a24ba1b247f787dfcc1c Mon Sep 17 00:00:00 2001
From: Leonard Hecker <lhecker@microsoft.com>
Date: Mon, 24 Jan 2022 19:08:26 +0100
Subject: [PATCH] AtlasEngine: Make shader hot-reloads possible in Windows
 Terminal (#12227)
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This minor change makes it possible to hot-reload the AtlasEngine shaders under
Windows Terminal. Launching an UWP application from Visual Studio doesn't
necessarily result in a working directory inside the project folder,
which makes relative file paths impractical. While the `__FILE__` macro is
compiler dependent it works under our build setup with MSVC at least.

## Validation Steps Performed

* Shader hot-reloading works under Windows Terminal ✅
---
 src/renderer/atlas/AtlasEngine.cpp | 31 +++++++++++++++---------------
 src/renderer/atlas/AtlasEngine.h   |  1 +
 src/renderer/atlas/pch.h           |  2 +-
 3 files changed, 17 insertions(+), 17 deletions(-)

diff --git a/src/renderer/atlas/AtlasEngine.cpp b/src/renderer/atlas/AtlasEngine.cpp
index bff52ab13cc..4e4e75966a0 100644
--- a/src/renderer/atlas/AtlasEngine.cpp
+++ b/src/renderer/atlas/AtlasEngine.cpp
@@ -9,8 +9,6 @@
 
 #include "../../interactivity/win32/CustomWindowMessages.h"
 
-#define SHADER_SOURCE_DIRECTORY LR"(..\..\renderer\atlas\)"
-
 // #### NOTE ####
 // This file should only contain methods that are only accessed by the caller of Present() (the "Renderer" class).
 // Basically this file poses the "synchronization" point between the concurrently running
@@ -192,16 +190,17 @@ AtlasEngine::AtlasEngine()
     _sr.isWindows10OrGreater = IsWindows10OrGreater();
 
 #ifndef NDEBUG
-    // If you run the Host.EXE project inside Visual Studio it'll have a working directory of
-    // $(SolutionDir)\src\host\exe. This relative path will thus end up in this source directory.
-    _sr.sourceCodeWatcher = wil::make_folder_change_reader_nothrow(SHADER_SOURCE_DIRECTORY, false, wil::FolderChangeEvents::FileName | wil::FolderChangeEvents::LastWriteTime, [this](wil::FolderChangeEvent, PCWSTR path) {
-        if (til::ends_with(path, L".hlsl"))
-        {
-            auto expected = INT64_MAX;
-            const auto invalidationTime = std::chrono::steady_clock::now() + std::chrono::milliseconds(100);
-            _sr.sourceCodeInvalidationTime.compare_exchange_strong(expected, invalidationTime.time_since_epoch().count(), std::memory_order_relaxed);
-        }
-    });
+    {
+        _sr.sourceDirectory = std::filesystem::path{ __FILE__ }.parent_path();
+        _sr.sourceCodeWatcher = wil::make_folder_change_reader_nothrow(_sr.sourceDirectory.c_str(), false, wil::FolderChangeEvents::FileName | wil::FolderChangeEvents::LastWriteTime, [this](wil::FolderChangeEvent, PCWSTR path) {
+            if (til::ends_with(path, L".hlsl"))
+            {
+                auto expected = INT64_MAX;
+                const auto invalidationTime = std::chrono::steady_clock::now() + std::chrono::milliseconds(100);
+                _sr.sourceCodeInvalidationTime.compare_exchange_strong(expected, invalidationTime.time_since_epoch().count(), std::memory_order_relaxed);
+            }
+        });
+    }
 #endif
 }
 
@@ -265,8 +264,8 @@ try
 
         try
         {
-            static const auto compile = [](const wchar_t* path, const char* target) {
-                const wil::unique_hfile fileHandle{ CreateFileW(path, GENERIC_READ, FILE_SHARE_READ, nullptr, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, nullptr) };
+            static const auto compile = [](const std::filesystem::path& path, const char* target) {
+                const wil::unique_hfile fileHandle{ CreateFileW(path.c_str(), GENERIC_READ, FILE_SHARE_READ, nullptr, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, nullptr) };
                 THROW_LAST_ERROR_IF(!fileHandle);
 
                 const auto fileSize = GetFileSize(fileHandle.get(), nullptr);
@@ -303,8 +302,8 @@ try
                 return blob;
             };
 
-            const auto vs = compile(SHADER_SOURCE_DIRECTORY "shader_vs.hlsl", "vs_4_1");
-            const auto ps = compile(SHADER_SOURCE_DIRECTORY "shader_ps.hlsl", "ps_4_1");
+            const auto vs = compile(_sr.sourceDirectory / L"shader_vs.hlsl", "vs_4_1");
+            const auto ps = compile(_sr.sourceDirectory / L"shader_ps.hlsl", "ps_4_1");
 
             THROW_IF_FAILED(_r.device->CreateVertexShader(vs->GetBufferPointer(), vs->GetBufferSize(), nullptr, _r.vertexShader.put()));
             THROW_IF_FAILED(_r.device->CreatePixelShader(ps->GetBufferPointer(), ps->GetBufferSize(), nullptr, _r.pixelShader.put()));
diff --git a/src/renderer/atlas/AtlasEngine.h b/src/renderer/atlas/AtlasEngine.h
index a9123128df4..4f930de2154 100644
--- a/src/renderer/atlas/AtlasEngine.h
+++ b/src/renderer/atlas/AtlasEngine.h
@@ -649,6 +649,7 @@ namespace Microsoft::Console::Render
             bool isWindows10OrGreater = true;
 
 #ifndef NDEBUG
+            std::filesystem::path sourceDirectory;
             wil::unique_folder_change_reader_nothrow sourceCodeWatcher;
             std::atomic<int64_t> sourceCodeInvalidationTime{ INT64_MAX };
 #endif
diff --git a/src/renderer/atlas/pch.h b/src/renderer/atlas/pch.h
index e6ede9efed7..5d59e23544b 100644
--- a/src/renderer/atlas/pch.h
+++ b/src/renderer/atlas/pch.h
@@ -7,7 +7,7 @@
 #define WIN32_LEAN_AND_MEAN
 
 #include <array>
-#include <iomanip>
+#include <filesystem>
 #include <optional>
 #include <sstream>
 #include <string_view>