Refresh rate driven rendering tick logic (#3375)

* Implement sync interval and refresh rate API for RenderViewportWidget

Signed-off-by: nvsickle <nvsickle@amazon.com>

* Measure actual frame timings in the viewport info overlay.

Takes the median of the sum of (frame end - frame begin) to provide more a more representative view of when frames begin and end.

Note: Until VSync is internally supported by the event loop, this will produce nearly identical frame timings as the frame will spend as much time as needed synchronously waiting on a vblank.

Signed-off-by: nvsickle <nvsickle@amazon.com>

* Make frame timing per-pipeline, wire up refresh rate info to ViewportContext

Signed-off-by: nvsickle <nvsickle@amazon.com>

* POC: Frame limit pipeline rendering

Signed-off-by: nvsickle <nvsickle@amazon.com>

* Switch Editor tick to every 0ms to allow better tick accumulation behavior

Signed-off-by: nvsickle <nvsickle@amazon.com>

* Move RPISystemComponent to the tick bus, remove tick accumulation logic

Signed-off-by: nvsickle <nvsickle@amazon.com>

* Add `AddToRenderTickAtInterval` to RenderPipeline API

This allows a pipeline to update at a set cadence, instead of rendering every frame or being directly told when to tick.

Signed-off-by: nvsickle <nvsickle@amazon.com>

* Make ViewportContext enforce a target framerate

-Adds GetFpsLimit/SetFpsLimit for actively limiting FPS
-Calculates a render tick interval based on vsync and the vps limit and updates the current pipeline

Signed-off-by: nvsickle <nvsickle@amazon.com>

* Add r_fps_limit and ed_inactive_viewport_fps_limit cvars

Signed-off-by: nvsickle <nvsickle@amazon.com>

* Quick null check from a crash I bumped into

Signed-off-by: nvsickle <nvsickle@amazon.com>

* Fix off-by-one on FPS calculation (shouldn't include the not-yet-rendered frame)

Signed-off-by: nvsickle <nvsickle@amazon.com>

* Clarify frame time begin initialization

Signed-off-by: nvsickle <nvsickle@amazon.com>

* Fix TrackView export.

Signed-off-by: nvsickle <nvsickle@amazon.com>

* Address some reviewer feedback, revert RPISystem API change, fix CPU profiler.

Signed-off-by: nvsickle <nvsickle@amazon.com>

* Add g_simulation_tick_rate

Signed-off-by: nvsickle <nvsickle@amazon.com>

* Address review feedback, make frame limit updates event driven

Signed-off-by: nvsickle <nvsickle@amazon.com>

* Remove timestamp update from ComponentApplication::Tick

Signed-off-by: nvsickle <nvsickle@amazon.com>

Code/Editor/Core/QtEditorApplication.cpp

@@ -44,7 +44,7 @@ enum
 {
     // in milliseconds
     GameModeIdleFrequency = 0,
-    EditorModeIdleFrequency = 1,
+    EditorModeIdleFrequency = 0,
     InactiveModeFrequency = 10,
     UninitializedFrequency = 9999,
 };

Code/Editor/TrackView/SequenceBatchRenderDialog.cpp

@@ -36,6 +36,9 @@
 #include "CryEdit.h"
 #include "Viewport.h"
 
+// Atom Renderer
+#include <Atom/RPI.Public/RPISystemInterface.h>
+
 AZ_PUSH_DISABLE_DLL_EXPORT_MEMBER_WARNING
 #include <TrackView/ui_SequenceBatchRenderDialog.h>
 AZ_POP_DISABLE_DLL_EXPORT_MEMBER_WARNING
@@ -1234,6 +1237,13 @@ void CSequenceBatchRenderDialog::OnKickIdleTimout()
         {
             componentApplication->TickSystem();
         }
+
+        // Directly tick the renderer, as it's no longer part of the system tick
+        if (auto rpiSystem = AZ::RPI::RPISystemInterface::Get())
+        {
+            rpiSystem->SimulationTick();
+            rpiSystem->RenderTick();
+        }
     }
 }
 

Code/Framework/AzCore/AzCore/Component/ComponentApplication.cpp

@@ -74,6 +74,8 @@
 #include <AzCore/Module/Environment.h>
 #include <AzCore/std/string/conversions.h>
 
+AZ_CVAR(float, g_simulation_tick_rate, 0, nullptr, AZ::ConsoleFunctorFlags::Null, "The rate at which the game simulation tick loop runs, or 0 for as fast as possible");
+
 static void PrintEntityName(const AZ::ConsoleCommandContainer& arguments)
 {
     if (arguments.empty())
@@ -1392,6 +1394,23 @@ namespace AZ
                 AZ_PROFILE_SCOPE(AzCore, "ComponentApplication::Tick:OnTick");
                 EBUS_EVENT(TickBus, OnTick, m_deltaTime, ScriptTimePoint(now));
             }
+
+            // If tick rate limiting is on, ensure (1 / g_simulation_tick_rate) ms has elapsed since the last frame,
+            // sleeping if there's still time remaining.
+            if (g_simulation_tick_rate > 0.f)
+            {
+                now = AZStd::chrono::system_clock::now();
+
+                // Work in microsecond durations here as that's the native measurement time for time_point
+                constexpr float microsecondsPerSecond = 1000.f * 1000.f;
+                const AZStd::chrono::microseconds timeBudgetPerTick(static_cast<int>(microsecondsPerSecond / g_simulation_tick_rate));
+                AZStd::chrono::microseconds timeUntilNextTick = m_currentTime + timeBudgetPerTick - now;
+
+                if (timeUntilNextTick.count() > 0)
+                {
+                    AZStd::this_thread::sleep_for(timeUntilNextTick);
+                }
+            }
         }
     }
 

Code/Framework/AzCore/AzCore/Component/TickBus.h

@@ -46,6 +46,8 @@ namespace AZ
 
         TICK_PRE_RENDER     = 750,     ///< Suggested tick handler position to update render-related data.
 
+        TICK_RENDER         = 800,     ///< Suggested tick handler position for rendering.
+
         TICK_DEFAULT        = 1000,    ///< Default tick handler position when the handler is constructed.
 
         TICK_UI             = 2000,    ///< Suggested tick handler position for UI components.