Add WebGPU Backend w/ Dawn Support (#3838)

include/mbgl/webgpu/command_encoder.hpp

@@ -0,0 +1,84 @@
+#pragma once
+
+#include <mbgl/gfx/command_encoder.hpp>
+#include <mbgl/util/containers.hpp>
+#include <webgpu/webgpu.h>
+
+#include <functional>
+#include <memory>
+#include <string>
+#include <unordered_set>
+#include <vector>
+
+namespace mbgl {
+namespace gfx {
+class Renderable;
+} // namespace gfx
+
+namespace webgpu {
+
+class Context;
+class RenderPass;
+class UploadPass;
+
+class CommandEncoder final : public gfx::CommandEncoder {
+public:
+    explicit CommandEncoder(Context& context_);
+    ~CommandEncoder() override;
+
+    webgpu::Context& getContext() { return context; }
+    const webgpu::Context& getContext() const { return context; }
+    WGPUCommandEncoder getEncoder() const { return encoder; }
+
+    std::unique_ptr<gfx::UploadPass> createUploadPass(const char* name, gfx::Renderable&) override;
+    std::unique_ptr<gfx::RenderPass> createRenderPass(const char* name, const gfx::RenderPassDescriptor&) override;
+
+    void present(gfx::Renderable&) override;
+
+    // WebGPU-specific: submit command buffer directly
+    void submitCommandBuffer();
+
+    template <typename TFunc>
+    void visitDebugGroups(TFunc f) {
+        for (const auto& item : debugGroupNames) {
+            f(item.name);
+        }
+    }
+
+private:
+    friend class RenderPass;
+    friend class UploadPass;
+
+    // Track a RenderPass, propagating debug groups to it
+    void trackRenderPass(RenderPass*);
+    // Stop tracking a RenderPass
+    void forgetRenderPass(RenderPass*);
+
+    // Track an UploadPass, propagating debug groups to it
+    void trackUploadPass(UploadPass*);
+    // Stop tracking a RenderPass
+    void forgetUploadPass(UploadPass*);
+
+    void pushDebugGroup(const char* name) override;
+    void popDebugGroup() override;
+
+protected:
+    struct GroupEntry {
+        std::string name;
+        std::size_t renderGroups;
+        std::size_t uploadGroups;
+    };
+
+protected:
+    webgpu::Context& context;
+    WGPUCommandEncoder encoder = nullptr;
+    std::vector<GroupEntry> debugGroupNames;
+    std::vector<gfx::DebugGroup<gfx::RenderPass>> renderDebugGroups;
+    std::vector<gfx::DebugGroup<gfx::UploadPass>> uploadDebugGroups;
+    mbgl::unordered_set<RenderPass*> renderPasses;
+    mbgl::unordered_set<UploadPass*> uploadPasses;
+    UploadPass* currentUploadPass = nullptr;
+};
+
+} // namespace webgpu
+} // namespace mbgl