Ask the client for frames between its steps

The frame pacer repaints the client's 3D windows at the user's frame rate
(HKCU\Software\T5DE\Graphics\FrameRate: 30, the default, adds nothing; 60, 120,
240, 360; 0 uncapped), so the client draws frames between its 30-per-second
steps. Only when affordable: a window is asked once its last frame is drawn,
and only if its frames take under three quarters of the interval; uncapped,
the client is left idle a third of a frame between frames. The engine's stats
now log frames per second.

The extra frames show the same scene for now.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

adapter/engine.hpp

@@ -1,10 +1,11 @@
 #pragma once
 // The adapter's engine: what the client draws with. Everything is recorded for the renderer process, which draws the
-// 3D view. The client's own Direct3D renderer gets everything too (state and resources: it still draws into render
-// targets and reads textures back, which the renderer process doesn't yet), but while the renderer process covers the
-// whole view, the client's renderer skips its frames' clears and draws. When the renderer process doesn't cover it
-// (it failed, or shows only part of the view, for comparing) the client's renderer draws everything, from the next
-// frame on.
+// 3D view and the render targets it makes. The client's own Direct3D renderer gets state and resources too (as a
+// fallback, and for reading textures back), but while the renderer process covers the whole view, the client's
+// renderer skips its frames' clears and draws. When the renderer process doesn't cover it (it failed, or shows only
+// part of the view, for comparing) the client's renderer draws everything, from the next frame on.
+
+#include <windows.h>
 
 #include <cstdint>
 #include <memory>
@@ -16,8 +17,8 @@ namespace t5de {
 
 class Engine final : public imvu::PiRenderEngine {
 public:
-    // recorder may be inactive (no renderer process).
-    Engine(imvu::SharedPtr<imvu::PiRenderEngine> inner, std::shared_ptr<Recorder> recorder);
+    // recorder may be inactive (no renderer process); window is the 3D window drawn into (frame_pacer.hpp), or null.
+    Engine(imvu::SharedPtr<imvu::PiRenderEngine> inner, std::shared_ptr<Recorder> recorder, HWND window);
     ~Engine() override;
 
     void resizeFrameBuffer(imvu::Vec2i size) override;
@@ -71,6 +72,7 @@ private:
 
     imvu::SharedPtr<imvu::PiRenderEngine> inner_;
     std::shared_ptr<Recorder> recorder_;
+    HWND window_;
     std::uint64_t frames_ = 0;
     bool takenOver_ = false; // this frame is drawn by the renderer process only
     imvu::PiRenderTarget* ourTarget_ = nullptr; // this frame's render target, if it's one of ours
@@ -87,6 +89,9 @@ private:
         std::uint32_t flat = 0; // setProjection with an orthographic projection (2D)
     };
     Stats stats_;
+    LARGE_INTEGER statsStart_{}; // when the stats' 300 frames started
+    LARGE_INTEGER frameStart_{}; // when the current frame began
+    bool windowFrame_ = false;   // the current frame is drawn into the window
     int statsLogged_ = 0;
 
 };