Fix T85144: Cycles crashes when editing render properties in viewport

rendering

Issue was caused by the sample pattern LUT always being freed and not
rebuilt when properties driving its dimensions were modified.

intern/cycles/render/integrator.cpp

@@ -115,7 +115,15 @@ void Integrator::device_update(Device *device, DeviceScene *dscene, Scene *scene
     }
   });
 
-  if (sampling_pattern_is_modified()) {
+  const bool need_update_lut = ao_samples_is_modified() || diffuse_samples_is_modified() ||
+                               glossy_samples_is_modified() || max_bounce_is_modified() ||
+                               max_transmission_bounce_is_modified() ||
+                               mesh_light_samples_is_modified() || method_is_modified() ||
+                               sampling_pattern_is_modified() ||
+                               subsurface_samples_is_modified() ||
+                               transmission_samples_is_modified() || volume_samples_is_modified();
+
+  if (need_update_lut) {
     dscene->sample_pattern_lut.tag_realloc();
   }
 
@@ -248,7 +256,7 @@ void Integrator::device_update(Device *device, DeviceScene *dscene, Scene *scene
   int dimensions = PRNG_BASE_NUM + max_samples * PRNG_BOUNCE_NUM;
   dimensions = min(dimensions, SOBOL_MAX_DIMENSIONS);
 
-  if (sampling_pattern_is_modified()) {
+  if (need_update_lut) {
     if (sampling_pattern == SAMPLING_PATTERN_SOBOL) {
       uint *directions = dscene->sample_pattern_lut.alloc(SOBOL_BITS * dimensions);
 
@@ -272,6 +280,7 @@ void Integrator::device_update(Device *device, DeviceScene *dscene, Scene *scene
     }
   }
 
+  dscene->sample_pattern_lut.clear_modified();
   clear_modified();
 }
 
@@ -292,6 +301,11 @@ void Integrator::tag_update(Scene *scene, uint32_t flag)
     tag_ao_bounces_modified();
   }
 
+  if ((flag & LIGHT_SAMPLES_MODIFIED) && (method == BRANCHED_PATH)) {
+    /* the number of light samples may affect the size of the sample_pattern_lut */
+    tag_sampling_pattern_modified();
+  }
+
   if (filter_glossy_is_modified()) {
     foreach (Shader *shader, scene->shaders) {
       if (shader->has_integrator_dependency) {

intern/cycles/render/integrator.h

@@ -92,6 +92,7 @@ class Integrator : public Node {
   enum : uint32_t {
     AO_PASS_MODIFIED = (1 << 0),
     BACKGROUND_AO_MODIFIED = (1 << 1),
+    LIGHT_SAMPLES_MODIFIED = (1 << 2),
 
     /* tag everything in the manager for an update */
     UPDATE_ALL = ~0u,

intern/cycles/render/light.cpp

@@ -164,6 +164,10 @@ void Light::tag_update(Scene *scene)
 {
   if (is_modified()) {
     scene->light_manager->tag_update(scene, LightManager::LIGHT_MODIFIED);
+
+    if (samples_is_modified()) {
+      scene->integrator->tag_update(scene, Integrator::LIGHT_SAMPLES_MODIFIED);
+    }
   }
 }