imguiOverlay.h

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//
// ImGui overlay for VisuTwin Canvas — digital twin HUD rendering.
//
// Provides GPU-accelerated UI overlays rendered on top of the 3D scene:
// - Floating data panels, sensor readouts, charts (via ImPlot)
// - 3D-anchored labels projected to screen space
// - Digital twin dark glassmorphism theme
//
// Integration point: hook into Engine's "postrender" event so the overlay
// renders after all 3D passes but before the frame is presented.
//
//
#pragma once
 
#include <functional>
#include <string>
#include <vector>
 
#include "core/math/color.h"
#include "core/math/matrix4.h"
#include "core/math/vector3.h"
 
union SDL_Event;
struct SDL_Window;
 
namespace visutwin::canvas
{
    class MetalGraphicsDevice;
 
    // ── 3D-anchored label descriptor ─────────────────────────────────────
 
    struct Label3D
    {
        Vector3 worldPos;
        std::string text;
        Color color = Color(0.94f, 0.96f, 0.98f, 0.95f);  // slate-100
        float fontSize = 0.0f;  // 0 = default
    };
 
    // ── ImGui overlay lifecycle manager ──────────────────────────────────
 
    class ImGuiOverlay
    {
    public:
        ImGuiOverlay() = default;
        ~ImGuiOverlay();
 
        // Non-copyable, movable
        ImGuiOverlay(const ImGuiOverlay&) = delete;
        ImGuiOverlay& operator=(const ImGuiOverlay&) = delete;
        ImGuiOverlay(ImGuiOverlay&&) noexcept;
        ImGuiOverlay& operator=(ImGuiOverlay&&) noexcept;

        void init(MetalGraphicsDevice* device, SDL_Window* window);

        bool processEvent(const SDL_Event& event);

        bool wantCaptureMouse() const;

        bool wantCaptureKeyboard() const;

        void beginFrame();

        void endFrame();

        void renderToGPU();

        void shutdown();

        bool isInitialized() const { return _initialized; }
 
        // ── 3D-anchored label helpers ────────────────────────────────────

        void setViewProjection(const Matrix4& vp) { _viewProjection = vp; }

        void setWindowSize(int width, int height) { _windowW = width; _windowH = height; }

        void label3D(const Vector3& worldPos, const char* text,
                     const Color& color = Color(0.94f, 0.96f, 0.98f, 0.95f));

        void panelLabel3D(const Vector3& worldPos, const char* title, const char* body,
                          const Color& panelColor = Color(0.06f, 0.09f, 0.16f, 0.88f));
 
        // ── Theme ────────────────────────────────────────────────────────

        static void applyDigitalTwinTheme();
 
    private:
        bool worldToScreen(const Vector3& worldPos, float& screenX, float& screenY) const;
 
        MetalGraphicsDevice* _device = nullptr;
        SDL_Window* _window = nullptr;
        bool _initialized = false;
 
        // View-projection for 3D label projection
        Matrix4 _viewProjection;
        int _windowW = 1280;
        int _windowH = 900;
    };
 
} // namespace visutwin::canvas