Add initial base implementation for WebGPU rendering backend

Source/Engine/GraphicsDevice/WebGPU/RenderToolsWebGPU.h

@@ -0,0 +1,74 @@
+// Copyright (c) Wojciech Figat. All rights reserved.
+
+#pragma once
+
+#if GRAPHICS_API_WEBGPU
+
+#include "Engine/Core/Types/String.h"
+#include "IncludeWebGPU.h"
+#include <emscripten/emscripten.h>
+
+enum class PixelFormat : unsigned;
+
+/// <summary>
+/// User data used by AsyncCallbackWebGPU to track state adn result.
+/// </summary>
+struct AsyncCallbackDataWebGPU
+{
+    String Message;
+    uint32 Status = 0;
+    intptr Result = 0;
+    double WaitTime = 0;
+
+    FORCE_INLINE void Call(bool success, uint32 status, WGPUStringView message)
+    {
+        Status = status;
+        if (!success)
+            Message.Set(message.data, message.data ? (int32)message.length : 0);
+        Platform::AtomicStore(&Result, success ? 1 : 2);
+    }
+};
+
+/// <summary>
+/// Helper utility to run WebGPU APIs that use async callback in sync by waiting on the spontaneous call back with an active-waiting loop.
+/// </summary>
+template<typename CallbackInfo, typename UserData = AsyncCallbackDataWebGPU>
+struct AsyncCallbackWebGPU
+{
+    UserData Data;
+    CallbackInfo Info;
+
+    AsyncCallbackWebGPU(CallbackInfo callbackDefault)
+        : Info(callbackDefault)
+    {
+        Info.mode = WGPUCallbackMode_AllowSpontaneous;
+        Info.userdata1 = &Data;
+    }
+
+    WGPUWaitStatus Wait()
+    {
+        auto startTime = Platform::GetTimeSeconds();
+        int32 ticksLeft = 500; // Wait max 5 second
+        while (Platform::AtomicRead(&Data.Result) == 0 && ticksLeft-- > 0)
+            emscripten_sleep(10);
+        if (ticksLeft <= 0)
+        {
+            Data.WaitTime = Platform::GetTimeSeconds() - startTime;
+            return WGPUWaitStatus_TimedOut;
+        }
+        return Data.Result == 1 ? WGPUWaitStatus_Success : WGPUWaitStatus_Error;
+    }
+};
+
+/// <summary>
+/// Set of utilities for rendering on Web GPU platform.
+/// </summary>
+class RenderToolsWebGPU
+{
+public:
+    static WGPUVertexFormat ToVertexFormat(PixelFormat format);
+    static WGPUTextureFormat ToTextureFormat(PixelFormat format);
+    static PixelFormat ToPixelFormat(WGPUTextureFormat format);
+};
+
+#endif