From 55c9cf8ff2c6bfa22b6a38e6600014ad56c6053e Mon Sep 17 00:00:00 2001
From: Johann Muszynski <johann.muszynski@gmail.com>
Date: Wed, 3 Jul 2024 20:23:36 +0300
Subject: [PATCH] Invalidate temporal accumulation on frame resize

---
 src/pt/deferred_renderer.cpp | 9 +++++++++
 src/pt/deferred_renderer.hpp | 2 ++
 2 files changed, 11 insertions(+)

diff --git a/src/pt/deferred_renderer.cpp b/src/pt/deferred_renderer.cpp
index 1f94670..07df8a7 100644
--- a/src/pt/deferred_renderer.cpp
+++ b/src/pt/deferred_renderer.cpp
@@ -555,6 +555,8 @@ void DeferredRenderer::resize(const GpuContext& gpuContext, const Extent2u& newS
 
     mDebugPass.resize(gpuContext, mAlbedoTextureView, mNormalTextureView, mDepthTextureView);
     mLightingPass.resize(gpuContext, mAlbedoTextureView, mNormalTextureView, mDepthTextureView);
+
+    invalidateTemporalAccumulation();
 }
 
 DeferredRenderer::GbufferPass::GbufferPass(
@@ -2041,4 +2043,11 @@ DeferredRenderer::PerfStats DeferredRenderer::getPerfStats() const
                 mResolvePassDurationsNs.begin(), mResolvePassDurationsNs.end(), 0ll)) /
             mResolvePassDurationsNs.size()};
 }
+
+void DeferredRenderer::invalidateTemporalAccumulation()
+{
+    // In the first frame of the accumulation sequence, we are forced to write the lighting pass
+    // sample straight to the accumulation buffer. This effectively resets the accumulation.
+    mFrameCount = 0;
+}
 } // namespace nlrs
diff --git a/src/pt/deferred_renderer.hpp b/src/pt/deferred_renderer.hpp
index b656605..8221b56 100644
--- a/src/pt/deferred_renderer.hpp
+++ b/src/pt/deferred_renderer.hpp
@@ -274,6 +274,8 @@ class DeferredRenderer
             Gui&               gui);
     };
 
+    void invalidateTemporalAccumulation();
+
     WGPUTexture               mDepthTexture;
     WGPUTextureView           mDepthTextureView;
     WGPUTexture               mAlbedoTexture;