Add targetFrameTime option for Vulkan backend

include/boo/IApplication.hpp

@@ -56,20 +56,21 @@ public:
 int ApplicationRun(IApplication::EPlatformType platform, IApplicationCallback& cb, SystemStringView uniqueName,
                    SystemStringView friendlyName, SystemStringView pname, const std::vector<SystemString>& args,
                    std::string_view gfxApi = {}, uint32_t samples = 1, uint32_t anisotropy = 1, bool deepColor = false,
-                   bool singleInstance = true);
+                   int64_t targetFrameTime = 0, bool singleInstance = true);
 extern IApplication* APP;
 
 static inline int ApplicationRun(IApplication::EPlatformType platform, IApplicationCallback& cb,
                                  SystemStringView uniqueName, SystemStringView friendlyName, int argc,
                                  const SystemChar** argv, std::string_view gfxApi = {}, uint32_t samples = 1,
-                                 uint32_t anisotropy = 1, bool deepColor = false, bool singleInstance = true) {
+                                 uint32_t anisotropy = 1, bool deepColor = false, int64_t targetFrameTime = 0,
+                                 bool singleInstance = true) {
   if (APP)
     return 1;
   std::vector<SystemString> args;
   for (int i = 1; i < argc; ++i)
     args.push_back(argv[i]);
   return ApplicationRun(platform, cb, uniqueName, friendlyName, argv[0], args, gfxApi, samples, anisotropy, deepColor,
-                        singleInstance);
+                        targetFrameTime, singleInstance);
 }
 
 } // namespace boo

include/boo/graphicsdev/Vulkan.hpp

@@ -97,6 +97,7 @@ struct VulkanContext {
   VkSampleCountFlags m_sampleCountDepth = VK_SAMPLE_COUNT_1_BIT;
   float m_anisotropy = 1.f;
   bool m_deepColor = false;
+  int64_t m_targetFrameTime = 0;
 
   std::unordered_map<uint32_t, VkSampler> m_samplers;
 

lib/graphicsdev/Common.cpp

@@ -1,5 +1,8 @@
 #include "Common.hpp"
+
 #include <cmath>
+#include <numeric>
+#include <thread>
 
 namespace boo {
 
@@ -12,4 +15,25 @@ void UpdateGammaLUT(ITextureD* tex, float gamma) {
   tex->unmap();
 }
 
+void Limiter::Sleep(nanotime_t targetFrameTime) {
+  if (targetFrameTime == 0) {
+    return;
+  }
+
+  auto start = delta_clock::now();
+  nanotime_t sleepTime = targetFrameTime - TimeSince(m_oldTime);
+  m_overhead = std::accumulate(m_overheadTimes.begin(), m_overheadTimes.end(), nanotime_t{}) /
+               static_cast<nanotime_t>(m_overheadTimes.size());
+  if (sleepTime > m_overhead) {
+    nanotime_t adjustedSleepTime = sleepTime - m_overhead;
+    std::this_thread::sleep_for(std::chrono::nanoseconds(adjustedSleepTime));
+    nanotime_t overslept = TimeSince(start) - adjustedSleepTime;
+    if (overslept < targetFrameTime) {
+      m_overheadTimes[m_overheadTimeIdx] = overslept;
+      m_overheadTimeIdx = (m_overheadTimeIdx + 1) % m_overheadTimes.size();
+    }
+  }
+  m_oldTime = delta_clock::now();
+}
+
 } // namespace boo

lib/graphicsdev/Common.hpp

@@ -7,6 +7,7 @@
 #include <atomic>
 #include <cassert>
 #include <condition_variable>
+#include <chrono>
 #include <mutex>
 #include <queue>
 #include <thread>
@@ -283,4 +284,22 @@ public:
 #define SCOPED_GRAPHICS_DEBUG_GROUP(...)
 #endif
 
+class Limiter {
+  using delta_clock = std::chrono::steady_clock;
+  using nanotime_t = std::chrono::nanoseconds::rep;
+
+public:
+  void Sleep(nanotime_t targetFrameTimeNs);
+
+private:
+  delta_clock::time_point m_oldTime;
+  std::array<nanotime_t, 4> m_overheadTimes{};
+  size_t m_overheadTimeIdx = 0;
+  nanotime_t m_overhead = 0;
+
+  nanotime_t TimeSince(delta_clock::time_point start) {
+    return std::chrono::duration_cast<std::chrono::nanoseconds>(delta_clock::now() - start).count();
+  }
+};
+
 } // namespace boo

lib/graphicsdev/Vulkan.cpp

@@ -2871,6 +2871,8 @@ struct VulkanCommandQueue final : IGraphicsCommandQueue {
 
   std::vector<boo::ObjToken<boo::IObj>> m_drawResTokens[2];
 
+  Limiter m_frameLimiter;
+
   void resetCommandBuffer() {
     ThrowIfFailed(vk::ResetCommandBuffer(m_cmdBufs[m_fillBuf], 0));
     VkCommandBufferBeginInfo cmdBufBeginInfo = {};
@@ -4076,6 +4078,7 @@ void VulkanCommandQueue::execute() {
     present.pResults = nullptr;
 
     ThrowIfFailed(vk::QueuePresentKHR(m_ctx->m_queue, &present));
+    m_frameLimiter.Sleep(m_ctx->m_targetFrameTime);
   }
 
   resetCommandBuffer();

lib/mac/ApplicationCocoa.mm

@@ -209,6 +209,7 @@ int ApplicationRun(IApplication::EPlatformType platform,
                    uint32_t samples,
                    uint32_t anisotropy,
                    bool deepColor,
+                   int64_t targetFrameTime,
                    bool singleInstance) {
   std::string thrName = std::string(friendlyName) + " Main Thread";
   logvisor::RegisterThreadName(thrName.c_str());

lib/win/ApplicationWin32.cpp

@@ -97,7 +97,7 @@ class ApplicationWin32 final : public IApplication {
 public:
   ApplicationWin32(IApplicationCallback& callback, SystemStringView uniqueName, SystemStringView friendlyName,
                    SystemStringView pname, const std::vector<SystemString>& args, std::string_view gfxApi,
-                   uint32_t samples, uint32_t anisotropy, bool deepColor, bool singleInstance)
+                   uint32_t samples, uint32_t anisotropy, bool deepColor, int64_t targetFrameTime, bool singleInstance)
   : m_callback(callback), m_uniqueName(uniqueName), m_friendlyName(friendlyName), m_pname(pname), m_args(args) {
     m_3dCtx.m_ctx11.m_sampleCount = samples;
     m_3dCtx.m_ctx11.m_anisotropy = anisotropy;
@@ -112,6 +112,7 @@ public:
     g_VulkanContext.m_sampleCountDepth = samples;
     g_VulkanContext.m_anisotropy = anisotropy;
     g_VulkanContext.m_deepColor = deepColor;
+    g_VulkanContext.m_targetFrameTime = targetFrameTime;
 #endif
 
     HMODULE dxgilib = LoadLibraryW(L"dxgi.dll");
@@ -472,7 +473,7 @@ IApplication* APP = nullptr;
 int ApplicationRun(IApplication::EPlatformType platform, IApplicationCallback& cb, SystemStringView uniqueName,
                    SystemStringView friendlyName, SystemStringView pname, const std::vector<SystemString>& args,
                    std::string_view gfxApi, uint32_t samples, uint32_t anisotropy, bool deepColor,
-                   bool singleInstance) {
+                   int64_t targetFrameTime, bool singleInstance) {
   std::string thrName = WCSTMBS(friendlyName.data()) + " Main Thread";
   logvisor::RegisterThreadName(thrName.c_str());
   if (APP)
@@ -501,7 +502,7 @@ int ApplicationRun(IApplication::EPlatformType platform, IApplicationCallback& c
   RegisterClassW(&wndClass);
 
   APP = new ApplicationWin32(cb, uniqueName, friendlyName, pname, args, gfxApi, samples, anisotropy, deepColor,
-                             singleInstance);
+                             targetFrameTime, singleInstance);
   int ret = APP->run();
   delete APP;
   APP = nullptr;

lib/x11/ApplicationUnix.cpp

@@ -125,7 +125,7 @@ namespace boo {
 int ApplicationRun(IApplication::EPlatformType platform, IApplicationCallback& cb, std::string_view uniqueName,
                    std::string_view friendlyName, std::string_view pname, const std::vector<std::string>& args,
                    std::string_view gfxApi, uint32_t samples, uint32_t anisotropy, bool deepColor,
-                   bool singleInstance) {
+                   int64_t targetFrameTime, bool singleInstance) {
   std::string thrName = std::string(friendlyName) + " Main";
   logvisor::RegisterThreadName(thrName.c_str());
   if (APP)
@@ -135,7 +135,7 @@ int ApplicationRun(IApplication::EPlatformType platform, IApplicationCallback& c
                                  singleInstance);
   else if (platform == IApplication::EPlatformType::Xlib || platform == IApplication::EPlatformType::Auto)
     APP = new ApplicationXlib(cb, uniqueName, friendlyName, pname, args, gfxApi, samples, anisotropy, deepColor,
-                              singleInstance);
+                              targetFrameTime, singleInstance);
   else
     return 1;
   int ret = APP->run();

lib/x11/ApplicationXlib.hpp

@@ -202,7 +202,7 @@ class ApplicationXlib final : public IApplication {
 public:
   ApplicationXlib(IApplicationCallback& callback, std::string_view uniqueName, std::string_view friendlyName,
                   std::string_view pname, const std::vector<std::string>& args, std::string_view gfxApi,
-                  uint32_t samples, uint32_t anisotropy, bool deepColor, bool singleInstance)
+                  uint32_t samples, uint32_t anisotropy, bool deepColor, int64_t targetFrameTime, bool singleInstance)
   : m_callback(callback)
   , m_uniqueName(uniqueName)
   , m_friendlyName(friendlyName)
@@ -217,6 +217,7 @@ public:
     g_VulkanContext.m_sampleCountDepth = samples;
     g_VulkanContext.m_anisotropy = anisotropy;
     g_VulkanContext.m_deepColor = deepColor;
+    g_VulkanContext.m_targetFrameTime = targetFrameTime;
 
     /* Check for Vulkan presence and preference */
     bool tryVulkan = true;