Merge branch 'pkristof/nrcEmissives' into 'main'

[REMIX-5073][REMIX-3471][REMIX-3686][GH:128] Added Boost Emissives option to NRC to fix missing emissive lighting on indirect bounces with NRC Direct Lighting enabled

See merge request lightspeedrtx/dxvk-remix-nv!2022

Author: pkristof

RtxOptions.md

@@ -394,6 +394,7 @@ This file is auto-generated by RTX Remix. To regenerate it, run Remix with `DXVK
 |rtx.neeCache.uniformSamplingProbability|float|0.1|||Uniform sampling probability\.|
 |rtx.neuralRadianceCache.allowRussianRouletteOnUpdate|bool|False||||
 |rtx.neuralRadianceCache.averageTrainingBouncesPerPath|float|2.15|||Average number of bounces per path used to calculate max training dimensions\.<br>Lower values result in higher max training dimensions and higher memory requirements by NRC\.<br>Lower values boost training dimensions to allows for more training records to get generated in scenes with very few / 1\-2 bounces<br>\(i\.e\. most of the view being into the sky with small geometric footprint on\-screen\)\.<br>|
+|rtx.neuralRadianceCache.boostEmissives|bool|True|||Preserves emissive lighting on indirect bounces where NRC would otherwise terminate the path before evaluating it\.<br>When Include Direct Lighting is enabled, NRC terminates paths immediately on cache hit, skipping emissive evaluation\.<br>The cache cannot accurately represent sharp emissive features, so this option defers termination<br>until after MIS\-weighted emissive accumulation\. May cause minor double\-counting in rare cases\.|
 |rtx.neuralRadianceCache.clearBuffersOnFrameStart|bool|False|||Clears buffers for NRC before they are written to by the the Pathtracer\.|
 |rtx.neuralRadianceCache.debugResolveMode|int|0|||Debug Visualization Mode\.|
 |rtx.neuralRadianceCache.enableAdaptiveTrainingDimensions|bool|True|||Enables adaptive training dimensions that scale based off pathtracer's execution behavior on a given scene\.|

src/dxvk/rtx_render/rtx_neural_radiance_cache.cpp

@@ -285,6 +285,7 @@ namespace dxvk {
 
       RemixGui::Checkbox("Learn Irradiance", &NrcOptions::learnIrradianceObject());
       RemixGui::Checkbox("Include Direct Lighting", &NrcOptions::includeDirectLightingObject());
+      RemixGui::Checkbox("Boost Emissives", &NrcOptions::boostEmissivesObject());
 
       RemixGui::DragInt("Max Number of Training Iterations", &NrcOptions::maxNumTrainingIterationsObject(), 1.f, 1, 16, "%d", ImGuiSliderFlags_AlwaysClamp);
       RemixGui::DragInt("Target Number of Training Iterations", &NrcOptions::targetNumTrainingIterationsObject(), 1.f, 1, 16, "%d", ImGuiSliderFlags_AlwaysClamp);
@@ -488,6 +489,8 @@ namespace dxvk {
     }
 
     nrcArgs.trainingLuminanceClamp = NrcOptions::luminanceClampMultiplier() * NrcOptions::maxExpectedAverageRadianceValue();
+
+    nrcArgs.boostEmissives = NrcOptions::boostEmissives();
   }
 
   const Vector2& NeuralRadianceCache::getNumQueryPixelsPerTrainingPixel() const {

src/dxvk/rtx_render/rtx_neural_radiance_cache.h

@@ -52,6 +52,11 @@ namespace dxvk {
 
       RTX_OPTION("rtx.neuralRadianceCache", bool, learnIrradiance, true, "");
       RTX_OPTION_ENV("rtx.neuralRadianceCache", bool, includeDirectLighting, true, "RTX_NRC_INCLUDE_DIRECT_LIGHTING", "");
+      RTX_OPTION("rtx.neuralRadianceCache", bool, boostEmissives, true,
+                 "Preserves emissive lighting on indirect bounces where NRC would otherwise terminate the path before evaluating it.\n"
+                 "When Include Direct Lighting is enabled, NRC terminates paths immediately on cache hit, skipping emissive evaluation.\n"
+                 "The cache cannot accurately represent sharp emissive features, so this option defers termination\n"
+                 "until after MIS-weighted emissive accumulation. May cause minor double-counting in rare cases.");
       RTX_OPTION("rtx.neuralRadianceCache", bool, resetHistory, false, "");
       RTX_OPTION("rtx.neuralRadianceCache", bool, allowRussianRouletteOnUpdate, false, "");
       RTX_OPTION_ARGS("rtx.neuralRadianceCache", uint32_t, targetNumTrainingIterations, 4,

src/dxvk/shaders/rtx/algorithm/integrator_indirect.slangh

@@ -396,7 +396,8 @@ void integratePathVertex(
   {  
     nrcProgressState = updateNrcOnHit(pathState, surfaceInteraction, polymorphicSurfaceMaterialInteraction);
 
-    if (nrcProgressState == NrcProgressState::TerminateImmediately)
+    // Terminate prior to resolving surface's emissive contribution if NRC indicates so and boostEmissives is not enabled.
+    if (nrcProgressState == NrcProgressState::TerminateImmediately && !cb.nrcArgs.boostEmissives)
     {
       pathState.continuePath = false;
       return;
@@ -434,8 +435,10 @@ void integratePathVertex(
   }
 
   // If the camera index changed then this ray passed through a render target. Cast a ray from the new camera.
-  if (cb.enableRaytracedRenderTarget && isRaytracedRenderTarget && pathState.bounceIteration == 1)
-  {
+  // Note: NRC TerminateImmediately with boostEmissives must take priority as a query record has already been created
+  if (cb.enableRaytracedRenderTarget && isRaytracedRenderTarget && pathState.bounceIteration == 1
+      && !(ENABLE_NRC && nrcProgressState == NrcProgressState::TerminateImmediately))
+  { 
     Ray newRay = rayCreateRenderTarget(cb.renderTargetCamera, surfaceInteraction.textureCoordinates, ray);
     pathState.origin = newRay.origin;
     pathState.direction = newRay.direction;
@@ -513,6 +516,16 @@ void integratePathVertex(
     accumulateRadiance(pathState, emissiveLightRadiance);
   }
 
+  // When boostEmissives is enabled, defer TerminateImmediately until after emissive accumulation
+  // so that the hit surface's emissive self-emission is properly MIS-weighted.
+  // Without this, emissive lighting is lost on TerminateImmediately paths (includeDirectLighting=true)
+  // because NRC's irradiance cache poorly captures sharp emissive features.
+  if (ENABLE_NRC && nrcProgressState == NrcProgressState::TerminateImmediately && cb.nrcArgs.boostEmissives)
+  {
+    pathState.continuePath = false;
+    return;
+  }
+
 // We don't need to sample lights or surface rays in the portal closest hit shader
 #if (SURFACE_MATERIAL_RESOLVE_TYPE_ACTIVE_MASK & SURFACE_MATERIAL_RESOLVE_TYPE_RAY_PORTAL) != 0
   if (materialType == surfaceMaterialTypeOpaque || materialType == surfaceMaterialTypeTranslucent)

src/dxvk/shaders/rtx/pass/nrc_args.h

@@ -46,4 +46,9 @@ struct NrcArgs {
 
   vec3 sceneBoundsMax;
   float trainingLuminanceClamp;
+
+  uint boostEmissives;
+  uint pad0;
+  uint pad1;
+  uint pad2;
 };