Fix T79680, T79680: confusing viewport denoise start sample behavior

1 files changed, 8 insertions, 1 deletions

diff --git a/intern/cycles/render/session.cpp b/intern/cycles/render/session.cpp
index 08a8cb08254..70c4214c684 100644
--- a/intern/cycles/render/session.cpp
+++ b/intern/cycles/render/session.cpp
@@ -1156,8 +1156,15 @@ bool Session::render_need_denoise(bool &delayed)
     return false;
   }
 
+  /* Immediately denoise when we reach the start sample or last sample. */
+  const int num_samples_finished = tile_manager.state.sample + 1;
+  if (num_samples_finished == params.denoising.start_sample ||
+      num_samples_finished == params.samples) {
+    return true;
+  }
+
   /* Do not denoise until the sample at which denoising should start is reached. */
-  if (tile_manager.state.sample < min(params.denoising.start_sample, params.samples - 1)) {
+  if (num_samples_finished < params.denoising.start_sample) {
     return false;
   }