Support configuring particle scatter ratio in particle emitter system

src/rendering/SceneManager.cc

@@ -1128,6 +1128,21 @@ rendering::ParticleEmitterPtr SceneManager::UpdateParticleEmitter(Entity _id,
   if (_emitter.has_pose())
     emitter->SetLocalPose(msgs::Convert(_emitter.pose()));
 
+  // particle scatter ratio
+  if (_emitter.has_header())
+  {
+    for (int i = 0; i < _emitter.header().data_size(); ++i)
+    {
+      const auto &data = _emitter.header().data(i);
+      const std::string key = "particle_scatter_ratio";
+      if (data.key() == "particle_scatter_ratio" && data.value_size() > 0)
+      {
+        emitter->SetUserData(key, math::parseFloat(data.value(0)));
+        break;
+      }
+    }
+  }
+
   return emitter;
 }
 

src/systems/particle_emitter/ParticleEmitter.cc

@@ -258,6 +258,17 @@ void ParticleEmitter::Configure(const Entity &_entity,
         absolutePath);
   }
 
+  // particle scatter ratio
+  const std::string scatterRatioKey = "particle_scatter_ratio";
+  if (_sdf->HasElement(scatterRatioKey))
+  {
+    // todo(anyone) add particle_scatter_ratio field in next release of ign-msgs
+    auto data = this->dataPtr->emitter.mutable_header()->add_data();
+    data->set_key(scatterRatioKey);
+    std::string *value = data->add_value();
+    *value = _sdf->Get<std::string>(scatterRatioKey);
+  }
+
   igndbg << "Loading particle emitter:" << std::endl
          << this->dataPtr->emitter.DebugString() << std::endl;
 

test/integration/particle_emitter.cc

@@ -120,6 +120,24 @@ TEST_F(ParticleEmitterTest, SDFLoad)
                 // and let rendering do the findFile instead
                 EXPECT_EQ(std::string(),
                     _emitter->Data().color_range_image().data());
+
+                // particle scatter ratio is temporarily stored in header
+                bool hasParticleScatterRatio = false;
+                for (int i = 0; i < _emitter->Data().header().data_size(); ++i)
+                {
+                  for (int j = 0;
+                      j < _emitter->Data().header().data(i).value_size(); ++j)
+                  {
+                    if (_emitter->Data().header().data(i).key() ==
+                        "particle_scatter_ratio")
+                    {
+                      EXPECT_DOUBLE_EQ(0.01, math::parseFloat(
+                          _emitter->Data().header().data(i).value(0)));
+                      hasParticleScatterRatio = true;
+                    }
+                  }
+                }
+                EXPECT_TRUE(hasParticleScatterRatio);
               }
               else
               {

test/worlds/particle_emitter.sdf

@@ -121,6 +121,7 @@
         <color_end>0 1 0</color_end>
         <scale_rate>10</scale_rate>
         <color_range_image>/path/to/dummy_image.png</color_range_image>
+        <particle_scatter_ratio>0.01</particle_scatter_ratio>
       </plugin>
     </model>