Particles: support custom particle events in solver

Previously, there were only particle-birth and time-step events.
Now the solver can handle custom events. On the user level
this does not change anything yet. This feature of the solver
will be used by an upcoming Age Reached Event node and
possibly others. When this node exists, I can finally remove
the hardcoded maximum particle age.

1 files changed, 66 insertions, 2 deletions

diff --git a/source/blender/simulation/intern/simulation_collect_influences.cc b/source/blender/simulation/intern/simulation_collect_influences.cc
index c744defb7d5..c309d18c43a 100644
--- a/source/blender/simulation/intern/simulation_collect_influences.cc
+++ b/source/blender/simulation/intern/simulation_collect_influences.cc
@@ -674,12 +674,18 @@ class ParticleConditionAction : public ParticleAction {
       }
 
       if (action_true_ != nullptr) {
-        ParticleChunkContext chunk_context{true_indices.as_span(), context.particles.attributes};
+        ParticleChunkContext chunk_context{context.particles.state,
+                                           true_indices.as_span(),
+                                           context.particles.attributes,
+                                           context.particles.integration};
         ParticleActionContext action_context{context.solve_context, chunk_context};
         action_true_->execute(action_context);
       }
       if (action_false_ != nullptr) {
-        ParticleChunkContext chunk_context{false_indices.as_span(), context.particles.attributes};
+        ParticleChunkContext chunk_context{context.particles.state,
+                                           false_indices.as_span(),
+                                           context.particles.attributes,
+                                           context.particles.integration};
         ParticleActionContext action_context{context.solve_context, chunk_context};
         action_false_->execute(action_context);
       }
@@ -753,6 +759,63 @@ static void optimize_function_network(CollectContext &context)
   // WM_clipboard_text_set(network.to_dot().c_str(), false);
 }
 
+class AgeReachedEvent : public ParticleEvent {
+ private:
+  std::string attribute_name_;
+
+ public:
+  AgeReachedEvent(std::string attribute_name) : attribute_name_(std::move(attribute_name))
+  {
+  }
+
+  void filter(ParticleEventFilterContext &context) const override
+  {
+    Span<float> birth_times = context.particles.attributes.get<float>("Birth Time");
+    Span<int> has_been_triggered = context.particles.attributes.get<int>(attribute_name_);
+    const float age = 5.0f;
+
+    const float end_time = context.particles.integration->end_time;
+    for (int i : context.particles.index_mask) {
+      if (has_been_triggered[i]) {
+        continue;
+      }
+      const float birth_time = birth_times[i];
+      const float trigger_time = birth_time + age;
+      if (trigger_time > end_time) {
+        continue;
+      }
+
+      const float duration = context.particles.integration->durations[i];
+      TimeInterval interval(end_time - duration, duration);
+      const float time_factor = interval.safe_factor_at_time(trigger_time);
+
+      context.factor_dst[i] = std::max<float>(0.0f, time_factor);
+    }
+  }
+
+  void execute(ParticleActionContext &context) const override
+  {
+    MutableSpan<int> dead_states = context.particles.attributes.get<int>("Dead");
+    MutableSpan<int> has_been_triggered = context.particles.attributes.get<int>(attribute_name_);
+    for (int i : context.particles.index_mask) {
+      dead_states[i] = true;
+      has_been_triggered[i] = 1;
+    }
+  }
+};
+
+static void collect_age_reached_events(CollectContext &context)
+{
+  /* TODO: Actually implement an Age Reached Event node. */
+  std::string attribute_name = "Has Been Triggered";
+  const AgeReachedEvent &event = context.resources.construct<AgeReachedEvent>(AT, attribute_name);
+  for (const DNode *dnode : context.particle_simulation_nodes) {
+    StringRefNull name = get_identifier(context, *dnode);
+    context.influences.particle_events.add_as(name, &event);
+    context.influences.particle_attributes_builder.lookup_as(name)->add<int>(attribute_name, 0);
+  }
+}
+
 void collect_simulation_influences(Simulation &simulation,
                                    ResourceCollector &resources,
                                    SimulationInfluences &r_influences,
@@ -774,6 +837,7 @@ void collect_simulation_influences(Simulation &simulation,
   collect_emitters(context);
   collect_birth_events(context);
   collect_time_step_events(context);
+  collect_age_reached_events(context);
 
   optimize_function_network(context);