[HDRP][Path Tracing] Exposed 3 methods related to path tracing and accumulation. (#6197)

* Made a few methods related to path tracing and accumulation public.

* Updated changelog.

Author: eturquin

com.unity.render-pipelines.high-definition/CHANGELOG.md

@@ -12,6 +12,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Added new functions that sample the custom buffer in custom passes (CustomPassSampleCustomColor and CustomPassLoadCustomColor) to handle the RTHandleScale automatically.
 - Added new panels to Rendering Debugger Display Stats panel, displaying improved CPU/GPU frame timings and bottlenecks.
 - Added API to edit diffusion profiles and set IES on lights.
+- Added public API to reset path tracing accumulation, and check its status.
 
 ### Fixed
 - Fixed decal position when created from context menu. (case 1368987)

com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/Accumulation/SubFrameManager.cs

@@ -153,7 +153,7 @@ internal void PrepareNewSubFrame()
             foreach (int camID in m_CameraCache.Keys.ToList())
                 maxIteration = Math.Max(maxIteration, GetCameraData(camID).currentIteration);
 
-            if (maxIteration == m_AccumulationSamples)
+            if (maxIteration >= m_AccumulationSamples)
             {
                 Reset();
             }
@@ -264,6 +264,18 @@ public void PrepareNewSubFrame()
             m_SubFrameManager.PrepareNewSubFrame();
         }
 
+        /// <summary>
+        /// Checks if the multi-frame accumulation is completed for a given camera.
+        /// </summary>
+        /// <param name="hdCamera">Camera for which the accumulation status is checked.</param>
+        /// <returns><c>true</c> if the accumulation is completed, <c>false</c> otherwise.</returns>
+        public bool IsFrameCompleted(HDCamera hdCamera)
+        {
+            int camID = hdCamera.camera.GetInstanceID();
+            CameraData camData = m_SubFrameManager.GetCameraData(camID);
+            return camData.currentIteration >= m_SubFrameManager.subFrameCount;
+        }
+
         class RenderAccumulationPassData
         {
             public ComputeShader accumulationCS;

com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/PathTracing/PathTracing.cs

@@ -112,12 +112,26 @@ void ReleasePathTracing()
 #endif // UNITY_EDITOR
         }
 
-        internal void ResetPathTracing()
+        /// <summary>
+        /// Resets path tracing accumulation for all cameras.
+        /// </summary>
+        public void ResetPathTracing()
         {
             m_RenderSky = true;
             m_SubFrameManager.Reset();
         }
 
+        /// <summary>
+        /// Resets path tracing accumulation for a specific camera.
+        /// </summary>
+        /// <param name="hdCamera">Camera for which the accumulation is reset.</param>
+        public void ResetPathTracing(HDCamera hdCamera)
+        {
+            int camID = hdCamera.camera.GetInstanceID();
+            CameraData camData = m_SubFrameManager.GetCameraData(camID);
+            ResetPathTracing(camID, camData);
+        }
+
         internal CameraData ResetPathTracing(int camID, CameraData camData)
         {
             m_RenderSky = true;