Howto add a lightsource to a scene

[cgerlach]

Hi,

I am trying to integrate the iray integration framework into our renderengine as an additional render path. Therefore the complete scenegraph has to be created within this engine.

As a first test I was able to load a scenegraph file with iray and draw the output within our renderengine.

Now I am trying to create the complete iray scenegraph in our engine from scratch and populate it with the different objects our scenegraph provides. After hours staring at the documentation and the examples I did not manage to figure out how to create a simple light source without loading a complete scene from file. Can someone give me a hint howto do this? How for example do I create a simple point light?

Thanks.

[cgerlach]

Hi,

after some more digging I found the answer myself. As a newbie, I found it very hard to put all those pieces together that are required to create a light source (or more important a shader).

So here is a code snippet for creating a light source. This is just a 'hack' version, because all checks you should normally do are missing. Maybe it is of use for someone else or there are ideas how to do this in an easier way.

	// Import Light-Shader-Class
	mi::base::Handle<mi::IBoolean> list_elements (transaction->create<mi::IBoolean>( "Boolean"));
	list_elements->set_value (true);
	mi::base::Handle<mi::IMap> importer_options (transaction->create<mi::IMap> ("Map<Interface>"));
	importer_options->insert ("list_elements", list_elements.get());

	mi::base::Handle<mi::neuraylib::IImport_api> import_api (neuray->get_api_component<mi::neuraylib::IImport_api>());
	check_success( import_api.is_valid_interface());
	mi::base::Handle<const mi::IImport_result> import_result (import_api->import_elements (transaction, "light_point.msl", importer_options.get()));

	// Create Light-Shader
	mi::base::Handle<mi::IShader_class> light_shader_class (transaction->edit<mi::IShader_class> (import_result->get_element (0)));
	light_shader_class->create_function ("light_shader");

	mi::base::Handle<mi::IShader> light_shader (transaction->edit<mi::IShader> ("light_shader"));
	light_shader->edit_attribute<mi::IFloat32> ("intensity")->set_value (300.0);

	// Create Light
	mi::base::Handle<mi::ILight> light (transaction->create<mi::ILight> ("Light"));

	light->set_type (mi::LIGHT_POINT);
	light->set_distance (100.0);
	light->attach_shader (mi::LIGHT_SHADER, "light_shader");
	transaction->store (light.get (), _light.c_str ());

	// Create Light-Instance
	mi::base::Handle<mi::IInstance> light_instance (transaction->create<mi::IInstance> ("Instance"));

	mi::Float64_4_4 matrix_light (1.0);
	matrix_light.translate (2.0, 2.0, -20.0);

	light_instance->attach (_light.c_str ());
	light_instance->set_world_to_obj (matrix_light);

	transaction->store (light_instance.get (), _light_instance.c_str ());

	// Add Light-Instance to root group
	mi::base::Handle<mi::IGroup> edit_group (transaction->edit<mi::IGroup> ( _rootgroup.c_str ()));
	edit_group->attach (_light_instance.c_str ());

[Martin-Karl]

Hi, in the download section of iray (http://www.mentalimages.com/products...framework.html) you will find code examples and there is one specifically on lights.

Note that you need the latest version.