Common: add json utility functions for Vec3 serialization

Source/Core/Common/JsonUtil.cpp

@@ -0,0 +1,20 @@
+// Copyright 2024 Dolphin Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include "Common/JsonUtil.h"
+
+picojson::object ToJsonObject(const Common::Vec3& vec)
+{
+  picojson::object obj;
+  obj.emplace("x", vec.x);
+  obj.emplace("y", vec.y);
+  obj.emplace("z", vec.z);
+  return obj;
+}
+
+void FromJson(const picojson::object& obj, Common::Vec3& vec)
+{
+  vec.x = ReadNumericOrDefault<float>(obj, "x");
+  vec.y = ReadNumericOrDefault<float>(obj, "y");
+  vec.z = ReadNumericOrDefault<float>(obj, "z");
+}

Source/Core/Common/JsonUtil.h

@@ -3,10 +3,13 @@
 
 #pragma once
 
-#include <span>
+#include <string>
 
 #include <picojson.h>
 
+#include "Common/MathUtil.h"
+#include "Common/Matrix.h"
+
 // Ideally this would use a concept like, 'template <std::ranges::range Range>' to constrain it,
 // but unfortunately we'd need to require clang 15 for that, since the ranges library isn't
 // fully implemented until then, but this should suffice.
@@ -24,3 +27,18 @@ picojson::array ToJsonArray(const Range& data)
 
   return result;
 }
+
+template <typename Type>
+Type ReadNumericOrDefault(const picojson::object& obj, const std::string& key,
+                          Type default_value = Type{})
+{
+  const auto it = obj.find(key);
+  if (it == obj.end())
+    return default_value;
+  if (!it->second.is<double>())
+    return default_value;
+  return MathUtil::SaturatingCast<Type>(it->second.get<double>());
+}
+
+picojson::object ToJsonObject(const Common::Vec3& vec);
+void FromJson(const picojson::object& obj, Common::Vec3& vec);