2 files changed, 24 insertions, 9 deletions

diff --git a/intern/cycles/render/session.cpp b/intern/cycles/render/session.cpp
index acf9ca68889..ae0a2cf863a 100644
--- a/intern/cycles/render/session.cpp
+++ b/intern/cycles/render/session.cpp
@@ -908,9 +908,6 @@ void Session::set_samples(int samples)
     params.samples = samples;
     tile_manager.set_samples(samples);
 
-    {
-      thread_scoped_lock pause_lock(pause_mutex);
-    }
     pause_cond.notify_all();
   }
 }
@@ -946,6 +943,15 @@ void Session::set_denoising(bool denoising, bool optix_denoising)
   tile_manager.schedule_denoising = denoising && !buffers;
 }
 
+void Session::set_denoising_start_sample(int sample)
+{
+  if (sample != params.denoising_start_sample) {
+    params.denoising_start_sample = sample;
+
+    pause_cond.notify_all();
+  }
+}
+
 void Session::wait()
 {
   if (session_thread) {
@@ -1110,8 +1116,8 @@ void Session::denoise()
     return;
   }
 
-  /* It can happen that denoising was already enabled, but the scene still needs an update. */
-  if (scene->film->need_update || !scene->film->denoising_data_offset) {
+  /* Do not denoise viewport until the sample at which denoising should start is reached. */
+  if (!params.background && tile_manager.state.sample < params.denoising_start_sample) {
     return;
   }
 
@@ -1122,6 +1128,11 @@ void Session::denoise()
     return;
   }
 
+  /* It can happen that denoising was already enabled, but the scene still needs an update. */
+  if (scene->film->need_update || !scene->film->denoising_data_offset) {
+    return;
+  }
+
   /* Add separate denoising task. */
   DeviceTask task(DeviceTask::DENOISE);
 
diff --git a/intern/cycles/render/session.h b/intern/cycles/render/session.h
index 3ef2b70879a..40ec3979afd 100644
--- a/intern/cycles/render/session.h
+++ b/intern/cycles/render/session.h
@@ -53,6 +53,7 @@ class SessionParams {
   int2 tile_size;
   TileOrder tile_order;
   int start_resolution;
+  int denoising_start_sample;
   int pixel_size;
   int threads;
 
@@ -85,6 +86,7 @@ class SessionParams {
     samples = 1024;
     tile_size = make_int2(64, 64);
     start_resolution = INT_MAX;
+    denoising_start_sample = 0;
     pixel_size = 1;
     threads = 0;
 
@@ -109,9 +111,10 @@ class SessionParams {
   bool modified(const SessionParams &params)
   {
     return !(device == params.device && background == params.background &&
-             progressive_refine == params.progressive_refine
-             /* && samples == params.samples */
-             && progressive == params.progressive && experimental == params.experimental &&
+             progressive_refine == params.progressive_refine &&
+             /* samples == params.samples && denoising_start_sample ==
+                params.denoising_start_sample && */
+             progressive == params.progressive && experimental == params.experimental &&
              tile_size == params.tile_size && start_resolution == params.start_resolution &&
              pixel_size == params.pixel_size && threads == params.threads &&
              use_profiling == params.use_profiling &&
@@ -152,9 +155,10 @@ class Session {
 
   bool ready_to_reset();
   void reset(BufferParams &params, int samples);
-  void set_samples(int samples);
   void set_pause(bool pause);
+  void set_samples(int samples);
   void set_denoising(bool denoising, bool optix_denoising);
+  void set_denoising_start_sample(int sample);
 
   bool update_scene();
   bool load_kernels(bool lock_scene = true);