add openvr support, switch to 8.1 sdk, prepare for vr ui

src/main.cpp

@@ -6,6 +6,7 @@
 #include "image.h"
 #include "app.h"
 #include "keymap.h"
+#include "hmd.h"
 #include "../resource.h"
 
 #include <shellscalingapi.h>
@@ -564,6 +565,21 @@ int main(int argc, char** argv)
     LOG("init app");
     App::I.init();
 
+    Vive* vive = nullptr;
+    if (!sandboxed)
+    {
+        vive = new Vive;
+        vive->on_draw = [](const glm::mat4& proj, const glm::mat4& view) { App::I.vr_draw(proj, view); };
+        async_lock();
+        if (!vive->Initialize())
+        {
+            delete vive;
+            vive = nullptr;
+            LOG("VR: failed to initialize vive");
+        }
+        async_unlock();
+    }
+
     LOG("show main window");
     ShowWindow(hWnd, SW_NORMAL);
 
@@ -689,6 +705,35 @@ int main(int argc, char** argv)
         }
     });
 
+    std::mutex hmd_render_mutex;
+    std::condition_variable hmd_render_cv;
+
+    std::thread hmd_renderer([&] {
+        BT_SetTerminate();
+        LOG("start hmd render thread");
+
+        const float target_tick_rate = 90;
+        unsigned long t0 = GetTickCount();
+        while (running && vive->Valid())
+        {
+            std::unique_lock<std::mutex> lock(hmd_render_mutex);
+            unsigned long t1 = GetTickCount();
+            float dt = (float)(t1 - t0) / 1000.0f;
+
+            async_lock();
+            vive->Draw();
+            async_unlock();
+
+            const int framerate = (1.f / target_tick_rate) * 1000;
+            const int diff = framerate - (t1 - t0);
+            hmd_render_cv.wait_for(lock, std::chrono::milliseconds(diff));
+        }
+        async_lock();
+        vive->Terminate();
+        async_unlock();
+    });
+
+
     MSG msg;
     LOG("start main loop");
     while (running)
@@ -710,6 +755,8 @@ int main(int argc, char** argv)
     render_cv.notify_all();
     if (renderer.joinable())
         renderer.join();
+    if (hmd_renderer.joinable())
+        hmd_renderer.join();
     App::I.terminate();
     // Clean up
     WacomTablet::I.terminate();