Scene3D: port mesh material fixes from ign-gazebo (#191)

As noted in #137, the Scene3D plugin was forked for use
in ign-gazebo, with the intention of consolidating back
with the ign-gui plugin to reduce duplication. This ports
some fixes for mesh material loading to ign-gui made in
gazebosim/gz-sim@897ef65 as part of
bitbucket PR 315.

Signed-off-by: Steve Peters <scpeters@openrobotics.org>

src/plugins/scene3d/Scene3D.cc

@@ -603,11 +603,7 @@ rendering::VisualPtr SceneManager::LoadVisual(const msgs::Visual &_msg)
  // Don't set a default material for meshes because they
  // may have their own
  // TODO(anyone) support overriding mesh material
- else if (_msg.geometry().has_mesh())
- {
- material = geom->Material();
- }
- else
+ else if (!_msg.geometry().has_mesh())
  {
  // create default material
  material = this->scene->Material("ign-grey");
@@ -621,15 +617,40 @@ rendering::VisualPtr SceneManager::LoadVisual(const msgs::Visual &_msg)
  material->SetMetalness(1.0f);
  }
  }
+ else
+ {
+ // meshes created by mesh loader may have their own materials
+ // update/override their properties based on input sdf element values
+ auto mesh = std::dynamic_pointer_cast<rendering::Mesh>(geom);
+ for (unsigned int i = 0; i < mesh->SubMeshCount(); ++i)
+ {
+ auto submesh = mesh->SubMeshByIndex(i);
+ auto submeshMat = submesh->Material();
+ if (submeshMat)
+ {
+ double productAlpha = (1.0-_msg.transparency()) *
+ (1.0 - submeshMat->Transparency());
+ submeshMat->SetTransparency(1 - productAlpha);
+ submeshMat->SetCastShadows(_msg.cast_shadows());
+ }
+ }
+ }
 
- material->SetTransparency(_msg.transparency());
-
- // TODO(anyone) Get roughness and metalness from message instead
- // of giving a default value.
- material->SetRoughness(0.3f);
- material->SetMetalness(0.3f);
-
- geom->SetMaterial(material);
+ if (material)
+ {
+ // set transparency
+ material->SetTransparency(_msg.transparency());
+
+ // cast shadows
+ material->SetCastShadows(_msg.cast_shadows());
+
+ geom->SetMaterial(material);
+ // todo(anyone) SetMaterial function clones the input material.
+ // but does not take ownership of it so we need to destroy it here.
+ // This is not ideal. We should let ign-rendering handle the lifetime
+ // of this material
+ this->scene->DestroyMaterial(material);
+ }
  }
  else
  {