[Bf-blender-cvs] [2bf02b14c6f] cycles-x: Fix wrong viewport render when enabling adaptive sampling in Cycles X

[Sergey Sharybin]

Commit: 2bf02b14c6f740d16b7b2e1565973cc384e81ce0
Author: Sergey Sharybin
Date:   Tue Aug 17 14:23:46 2021 +0200
Branches: cycles-x
https://developer.blender.org/rB2bf02b14c6f740d16b7b2e1565973cc384e81ce0

Fix wrong viewport render when enabling adaptive sampling in Cycles X

Steps to reproduce:
- Start viewport render
- Enable adaptive sampling

Caused by d5019b3838c: integrator's device update did not properly
detect change in sampler and hence did not rebuild the sampler LUT.

===================================================================

M	intern/cycles/render/integrator.cpp

===================================================================

diff --git a/intern/cycles/render/integrator.cpp b/intern/cycles/render/integrator.cpp
index 55d86701701..0e5e8821526 100644
--- a/intern/cycles/render/integrator.cpp
+++ b/intern/cycles/render/integrator.cpp
@@ -129,8 +129,20 @@ void Integrator::device_update(Device *device, DeviceScene *dscene, Scene *scene
     }
   });
 
+  KernelIntegrator *kintegrator = &dscene->data.integrator;
+
+  /* Adaptive sampling requires PMJ samples.
+   *
+   * This also makes detection of sampling pattern a bit more involved: can not rely on the changed
+   * state of socket, since its value might be different from the effective value used here. So
+   * instead compare with previous value in the KernelIntegrator. Only do it if the device was
+   * updated once (in which case the `sample_pattern_lut` will be allocated to a non-zero size). */
+  const SamplingPattern new_sampling_pattern = (use_adaptive_sampling) ? SAMPLING_PATTERN_PMJ :
+                                                                         sampling_pattern;
+
   const bool need_update_lut = max_bounce_is_modified() || max_transmission_bounce_is_modified() ||
-                               sampling_pattern_is_modified();
+                               dscene->sample_pattern_lut.size() == 0 ||
+                               kintegrator->sampling_pattern != new_sampling_pattern;
 
   if (need_update_lut) {
     dscene->sample_pattern_lut.tag_realloc();
@@ -138,8 +150,6 @@ void Integrator::device_update(Device *device, DeviceScene *dscene, Scene *scene
 
   device_free(device, dscene);
 
-  KernelIntegrator *kintegrator = &dscene->data.integrator;
-
   /* integrator parameters */
   kintegrator->min_bounce = min_bounce + 1;
   kintegrator->max_bounce = max_bounce + 1;
@@ -185,8 +195,7 @@ void Integrator::device_update(Device *device, DeviceScene *dscene, Scene *scene
                                            FLT_MAX :
                                            sample_clamp_indirect * 3.0f;
 
-  kintegrator->sampling_pattern = (use_adaptive_sampling) ? SAMPLING_PATTERN_PMJ :
-                                                            sampling_pattern;
+  kintegrator->sampling_pattern = new_sampling_pattern;
 
   if (light_sampling_threshold > 0.0f) {
     kintegrator->light_inv_rr_threshold = 1.0f / light_sampling_threshold;