Wrap IMVU's Direct3D renderer in the pass-through

IMVU's OpenGL renderer needs a real graphics driver; Direct3D also runs on Windows' basic display driver and is what most players use. The log can now be read while the client runs. Verified in rooms: every call goes through.

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

README.md

@@ -3,7 +3,7 @@
 A new 3D renderer for the IMVU Classic client, as a renderer plugin the client loads like its own OpenGL renderer.
 Part of [T5DE](https://git.t5de.dev/t5de/t5de); unofficial, not affiliated with IMVU.
 
-For now it's a pass-through: it wraps IMVU's OpenGL renderer and logs what each frame draws, to prove our
+For now it's a pass-through: it wraps IMVU's Direct3D renderer and logs what each frame draws, to prove our
 declarations of IMVU's interface (`docs/interface.md`).
 
 ## Building
@@ -20,6 +20,6 @@ That configures, builds `build/windows-x86/Release/t5deRenderEngine.dll` and run
 
 ## Trying it
 
-Copy `t5deRenderEngine.dll` into a T5DE client folder, and have the client load it in place of
-`glRenderEngine.dll` (a T5DE patch, to come), then choose OpenGL in Settings > Advanced. The log is
+Copy `t5deRenderEngine.dll` into a T5DE client folder built with the `t5de-renderer` patch, which has the OpenGL
+setting load it in place of `glRenderEngine.dll`, then choose OpenGL in Settings > Advanced. The log is
 `%TEMP%\t5de-renderer.log`.

docs/interface.md

@@ -79,9 +79,25 @@ virtual methods, IMVU's code only uses an engine through helpers that call its v
   ticks; `runApp` waits out `zero.dll`'s `millisecondsPerFrame`). Shorter ticks speed animations up. Smooth high
   frame rates need in-between poses: hooks in `SceneWindow.dll`'s animation update.
 
+## What the client draws
+
+From the pass-through (Direct3D, client 554.8, a few rooms):
+
+- A room frame: about 146 `drawTriangles`, each with its own `setModelSpace` (131) and `setTextures` (138), with
+  per-object alpha test, culling, normal inverting and blending, 252 texture-transform resets, 8 light updates; no
+  `drawLine`, `drawPointSprites` or `drawTrianglesFromMemory` in those rooms.
+- Every frame creates index and vertex buffers (4 and 12 in a room, with nothing new loading): most likely avatars,
+  skinned on the CPU and uploaded again each frame.
+- Each 3D window, and each room change, creates a new engine (`createRenderEngine`), so engines start and stop
+  often; frame buffers are resized freely (up to 3440x1272 here).
+- IMVU's OpenGL engine needs a real graphics driver (`ARB_multitexture`); on Windows' basic display driver
+  (virtual machines) it throws and the client falls back. Its exceptions are `std::exception`s our code can
+  catch.
+
 ## Plan
 
-1. Pass-through plugin (this repository's first version): wraps IMVU's OpenGL engine and logs what each frame
-   calls, proving our declarations.
+1. Pass-through plugin (done, verified in rooms): wraps IMVU's Direct3D engine, made with `SceneWindow.dll`'s
+   exported `createRenderer`, and logs what each frame calls, proving our declarations.
 2. Work out the layouts above.
-3. A renderer reproducing the current look on Direct3D 11 or OpenGL 4, then the improvements.
+3. A renderer reproducing the current look on Direct3D 11 (it also runs in software, on WARP, where OpenGL can't),
+   then the improvements.

include/t5de/imvu/render_engine.hpp

@@ -112,4 +112,16 @@ static_assert(sizeof(PiRenderEngine) == 12, "vtable pointer, magic, size");
 using IsRenderEngineSupported = int(__cdecl*)();
 using CreateRenderEngine = SharedPtr<PiRenderEngine>(__cdecl*)(SharedPtr<INativeWindow> window);
 
+// The renderers SceneWindow.dll's createRenderer makes (values from _avatarwindow.pyd's RendererType).
+enum class RendererType : int {
+    Direct3D = 1,    // RenderEngineDx, Direct3D 9
+    OpenGL = 2,      // the plugin glRenderEngine.dll
+    SwiftShader = 9, // RenderEngineDx on swiftshader.dll
+};
+
+// SceneWindow.dll's createRenderer(boost::shared_ptr<INativeWindow>, RendererType), exported by this name.
+using CreateRenderer = SharedPtr<PiRenderEngine>(__cdecl*)(SharedPtr<INativeWindow> window, RendererType type);
+inline constexpr const char* createRendererName =
+    "?createRenderer@@YA?AV?$shared_ptr@VPiRenderEngine@@@boost@@V?$shared_ptr@VINativeWindow@@@2@W4RendererType@@@Z";
+
 } // namespace t5de::imvu

src/log.cpp

@@ -1,5 +1,6 @@
 #include "log.hpp"
 
+#include <share.h>
 #include <windows.h>
 
 #include <cstdio>
@@ -17,9 +18,8 @@ std::FILE* open()
     if (length == 0 || length > MAX_PATH) {
         return nullptr;
     }
-    std::FILE* file = nullptr;
-    _wfopen_s(&file, (std::filesystem::path(temp) / L"t5de-renderer.log").c_str(), L"w");
-    return file;
+    // Shared, so it can be read while the client runs.
+    return _wfsopen((std::filesystem::path(temp) / L"t5de-renderer.log").c_str(), L"w", _SH_DENYNO);
 }
 
 } // namespace

src/passthrough_engine.hpp

@@ -1,5 +1,5 @@
 #pragma once
-// A renderer that forwards every call to another one (IMVU's OpenGL engine) and logs what a frame is made of: proof
+// A renderer that forwards every call to another one (IMVU's Direct3D engine) and logs what a frame is made of: proof
 // that our declaration of the interface matches IMVU's, and a way to see how the client draws.
 
 #include <array>

src/plugin.cpp

@@ -1,10 +1,9 @@
 // The renderer plugin's entry points, which SceneWindow.dll's createDLLRenderer looks up by name (exported
-// undecorated by plugin.def). For now the renderer is the pass-through: IMVU's OpenGL engine, wrapped.
+// undecorated by plugin.def). For now the renderer is the pass-through: IMVU's Direct3D engine, wrapped.
 
 #include <windows.h>
 
 #include <exception>
-#include <filesystem>
 
 #include "log.hpp"
 #include "passthrough_engine.hpp"
@@ -14,33 +13,20 @@ namespace {
 
 using namespace t5de;
 
-// The folder this DLL is in: the client's program folder.
-std::filesystem::path program_folder()
-{
-    HMODULE self = nullptr;
-    GetModuleHandleExW(GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS | GET_MODULE_HANDLE_EX_FLAG_UNCHANGED_REFCOUNT,
-                       reinterpret_cast<LPCWSTR>(&program_folder), &self);
-    wchar_t path[MAX_PATH];
-    GetModuleFileNameW(self, path, MAX_PATH);
-    return std::filesystem::path(path).parent_path();
-}
-
-// IMVU's OpenGL engine, from the plugin in the program folder (never unloaded: its engines use its code).
+// IMVU's Direct3D 9 engine, made by SceneWindow.dll (already loaded: it's what loads this plugin). Direct3D
+// rather than IMVU's OpenGL engine, which needs a real graphics driver: Direct3D also works on Windows' basic
+// display driver (virtual machines), and it's what most players use.
 imvu::SharedPtr<imvu::PiRenderEngine> create_imvu_engine(imvu::SharedPtr<imvu::INativeWindow> window)
 {
-    const auto dll = program_folder() / L"glRenderEngine.dll";
-    HMODULE module = LoadLibraryW(dll.c_str());
-    if (module == nullptr) {
-        log::info("can't load {}: error {}", dll.string(), GetLastError());
+    HMODULE scene_window = GetModuleHandleW(L"SceneWindow.dll");
+    auto create = scene_window == nullptr
+                      ? nullptr
+                      : reinterpret_cast<imvu::CreateRenderer>(GetProcAddress(scene_window, imvu::createRendererName));
+    if (create == nullptr) {
+        log::info("SceneWindow.dll's createRenderer not found");
         return {};
     }
-    auto supported = reinterpret_cast<imvu::IsRenderEngineSupported>(GetProcAddress(module, "isRenderEngineSupported"));
-    auto create = reinterpret_cast<imvu::CreateRenderEngine>(GetProcAddress(module, "createRenderEngine"));
-    if (supported == nullptr || create == nullptr || supported() == 0) {
-        log::info("{} isn't a usable renderer", dll.string());
-        return {};
-    }
-    return create(std::move(window));
+    return create(std::move(window), imvu::RendererType::Direct3D);
 }
 
 } // namespace
@@ -62,5 +48,8 @@ extern "C" imvu::SharedPtr<imvu::PiRenderEngine> __cdecl createRenderEngine(imvu
         // Exceptions mustn't cross into IMVU's code (a different C++ runtime).
         log::info("createRenderEngine failed: {}", e.what());
         return {};
+    } catch (...) {
+        log::info("createRenderEngine failed");
+        return {};
     }
 }