ON_Object::ObjectType() returns 0

openNURBS
1

I am trying to iterate through the model geometry list. But ON_Object::ObjectType() always returns zero…

ONX_Model model;
ONX_ModelComponentIterator it(model, ON_ModelComponent::Type::ModelGeometry);
const ON_ModelComponent* model_component = nullptr;
for (model_component = it.FirstComponent(); nullptr != model_component; model_component = it.NextComponent())
{
	const ON_ModelGeometryComponent* geo = ON_ModelGeometryComponent::Cast(model_component);
		if (nullptr != geo)
		{
			switch(geo->ObjectType())
			
			default:
				break;
			case ON::object_type::brep_object:
			//todo
			      break;

		}
		
}
2

Hi @rajeev,

ON::object_type is an old-style enum (declared as enum not enum class).

So instead of this:

case ON::object_type::brep_object:

You will want to do this:

case ON::brep_object:

Does this help?

– Dale

3

Thanks… that helped…

Using OpenNurbs v5, it was easy to find the layer, material and groups associated to the geometry objects, once the reference of the objects were available using ONX_Model_objects.

In the new scenario, I tried to cast the following without success…
//get layer index
const ON_ModelComponentReference model_ref_layer = model.LayerFromId(model_component->Id());
const ON_Layer* layer = ON_Layer::Cast(model_ref_layer.ModelComponent());
//get group index
const ON_ModelComponentReference model_ref_group = model.ComponentFromId(ON_ModelComponent::Type::Group, model_component->Id());
const ON_Group* group = ON_Group::Cast(model_ref_group.ModelComponent());
/get material index
const ON_ModelComponentReference model_ref_material = model.RenderMaterialFromId(model_component->Id());
const ON_Material* mat = ON_Material::Cast(model_ref_material.ModelComponent());

What is the correct way of finding the layer, material and groups, when we have the geometric objects.

4

Hi @rajeev,

In order to lookup referenced components, such as Layer, Material, Groups, etc., you first must obtain the model geometry attributes, or ON_3dmObjectAttributes object:

for (model_component = it.FirstComponent(); nullptr != model_component; model_component = it.NextComponent())
{
  const ON_ModelGeometryComponent* model_geometry = ON_ModelGeometryComponent::Cast(model_component);
  if (nullptr != model_geometry)
  {
    const ON_3dmObjectAttributes* attributes = model_geometry->Attributes(nullptr);
    if (nullptr != attributes)
    {
      // TODO
    }

Now that you have the attributes, you can use the helper functions on ONX_Model to access these components.

Here are a couple of helper functions you might find useful:

/*
Description:
  Returns a pointer to an ON_Layer object, given an object's attributes.
*/
static const ON_Layer* ON_LayerFromAttributes(
  const ONX_Model& model, 
  const ON_3dmObjectAttributes& attributes
)
{
  const ON_Layer* layer = nullptr;
  const ON_ModelComponentReference& model_component_ref = model.LayerFromAttributes(attributes);
  if (!model_component_ref.IsEmpty())
    layer = ON_Layer::Cast(model_component_ref.ModelComponent());
  return layer;
}

/*
Description:
  Returns a pointer to an ON_Material object, given an object's attributes.
*/
static const ON_Material* ON_MaterialFromAttributes(
  const ONX_Model& model, 
  const ON_3dmObjectAttributes& attributes
)
{
  const ON_Material* material = nullptr;
  const ON_ModelComponentReference& model_component_ref = model.RenderMaterialFromAttributes(attributes);
  if (!model_component_ref.IsEmpty())
    material = ON_Material::Cast(model_component_ref.ModelComponent());
  return material;
}

/*
Description:
  Returns pointers to ON_Group objects, given an object's attributes.
*/
static int ON_GroupsFromAttributes(const ONX_Model& model, const ON_3dmObjectAttributes& attributes, ON_SimpleArray<const ON_Group*>& groups)
{
  const int group_count = groups.Count();
  ON_SimpleArray<int> group_indices;
  if (attributes.GetGroupList(group_indices) > 0)
  {
    for (int i = 0; i < group_indices.Count(); i++)
    {
      ON_ModelComponentReference model_component_ref = model.ComponentFromIndex(ON_ModelComponent::Type::Group, i);
      if (!model_component_ref.IsEmpty())
      {
        const ON_Group* group = ON_Group::Cast(model_component_ref.ModelComponent());
        if (nullptr != group)
          groups.Append(group);
      }
    }
  }
  return groups.Count() - group_count;
}

Hope this helps.

– Dale

5

Thank you very much @dale

Wow! … I definitely went on a tangent. As soon as I get some time I will try to create a chart to illustrate the various links…

6

For those watching at home:

– Dale

1 Like