=================
Rendering Effects
=================


HOOPS Visualize Desktop makes several rendering effects available for when it is necessary to create an image of very high visual quality. In this tutorial, we'll use a model of a turbine engine to demonstrate reflection planes, two types of shadowing, and bloom. This tutorial will make use of the Sandbox application. For C++ users, the *mfc_sandbox* project is where you'll want to start from. ``CHPSView::OnUserCodeX`` function is where you'll want to place your code if you'd like to follow along with this tutorial. C# users will use the *wpf_sandbox* application - you'll place the code in ``DemoUserCommand**X**::Execute``.


.. _0301:

3.1 Load the Turbine Model
==========================

The first step after building and running the sandbox is to load the turbine model file. That file can be found in the *samples/data* directory in your HOOPS Visualize Desktop installation. This is an HSF file, so it can be loaded natively by HOOPS Visualize Desktop. Load it into the sandbox using the sandbox's main menu. 

Alternatively, you can programmatically load the file. To do this, first decide which segment you'll load the model into, and get a reference to it. For this tutorial we will use the model segment:

.. tabs::

	.. group-tab:: C++
	
		.. code-block:: cpp
		
			HPS::SegmentKey modelSegmentKey = GetCanvas().GetFrontView().GetAttachedModel().GetSegmentKey();
		   
	.. group-tab:: C#

		.. code-block:: cs
		
			HPS.SegmentKey modelSegmentKey = GetCanvas().GetFrontView().GetAttachedModel().GetSegmentKey();

Then, load the model using the following code. Replace ``mySegmentKey`` with what ever segment key you've decided to use:

.. tabs::

	.. group-tab:: C++
	
		.. literalinclude:: ../../../internals/tests/docs/source/cpp/00730_tutorial3_1.cpp
		   :start-after: //! [import_notifier]
		   :end-before: //! [import_notifier]
		   
	.. group-tab:: C#

		.. literalinclude:: ../../../internals/tests/docs/source/cs/00730_tutorial3_1.cs
		   :start-after: //! [import_notifier]
		   :end-before: //! [import_notifier]

More on loading HSFs can be found in :doc:`section 9.1 </prog_guide/0901_importing_files>` of the Programming Guide. After loading is complete, you should see the following image:

.. image:: images/03/3.1.a_default.png

*The default view of the turbine engine*

Notice the turbine doesn't look great at the moment. We'll fix that in the next section.


.. _0302:

3.2 Add a reflection plane and lighting
=======================================

The turbine looks flat because there are no lights in the scene, therefore, no lighting calculations are being performed. In the next code snippet, we'll add a light using ``InsertDistantLight``.

Another interesting change you can apply with relative ease is a reflection plane. Planes are specified in ``SetSimpleReflectionPlane`` using the geometric equation of a plane::

	Ax + By + Cz + D = 0

Additional options for the reflected image are also available - such as opacity, blurring, fading, and attenuation. We will also add lighting so the model appears more realistic. Place the following code into one of the ``UserCode`` or ``DemoUserCommand`` methods to activate it after the model is loaded.

.. tabs::

	.. group-tab:: C++
	
		.. literalinclude:: ../../../internals/tests/docs/source/cpp/00730_tutorial3_1.cpp
		   :start-after: //! [reflection]
		   :end-before: //! [reflection]
		   
	.. group-tab:: C#

		.. literalinclude:: ../../../internals/tests/docs/source/cs/00730_tutorial3_1.cs
		   :start-after: //! [reflection]
		   :end-before: //! [reflection]

Finally, don't forget to redraw the scene using ``GetCanvas().Update()``.

After rotating the model using the orbit operator (its in the ribbon control of the application), the resulting image should look like the one below:

.. image:: images/03/3.1.b.png

*The turbine engine with a reflection plane. Note that the window background has been changed to white for clarity.*

As with all extra rendering effects, additional processing time is required to achieve the resulting image. Always keep in mind the balance between rendering quality and performance, especially when dealing with complex scenes.


.. _0303:

3.3 Shadows
===========

In this section, we'll apply a drop shadow as well as shadow maps to the turbine model. Since a drop shadow doesn't normally look good with a reflection plane, we'll disable it to focus on shadows. The first type of shadowing we'll enable is shadow maps. Shadow maps allow the faces of geometry to cast a shadow over any type of geometry that is affected by a light. The first step is to enable shadowing in the segment, then we'll set the shadow map parameters:

.. tabs::

	.. group-tab:: C++
	
		.. literalinclude:: ../../../internals/tests/docs/source/cpp/00730_tutorial3_1.cpp
		   :start-after: //! [set_shadows]
		   :end-before: //! [set_shadows]
		   
	.. group-tab:: C#

		.. literalinclude:: ../../../internals/tests/docs/source/cs/00730_tutorial3_1.cs
		   :start-after: //! [set_shadows]
		   :end-before: //! [set_shadows]
		   
.. image:: images/03/t.3.1.c.png

*Here, you can see some of the parts in the foreground are casting shadows over the geometry behind it.*

Next, we'll enable drop shadows. Drop shadows are called *simple shadows* in HOOPS Visualize Desktop because the effect is highly constrained. First, the simple shadow can only be cast on a flat plane. Secondly, the shadow can only be generated from a single light source. For most engineering applications, however, the simple shadow creates an adequate effect.

.. tabs::

	.. group-tab:: C++
	
		.. literalinclude:: ../../../internals/tests/docs/source/cpp/00730_tutorial3_1.cpp
		   :start-after: //! [shadow_attributes]
		   :end-before: //! [shadow_attributes]
		   
	.. group-tab:: C#

		.. literalinclude:: ../../../internals/tests/docs/source/cs/00730_tutorial3_1.cs
		   :start-after: //! [shadow_attributes]
		   :end-before: //! [shadow_attributes]

.. image:: images/03/t.3.1.d.png

*The turbine with shadow maps and a simple shadow*


.. _0304:

3.4 Bloom
=========

Another effect that can improve the visual quality of a rendering is bloom. Bloom occurs when an intensely bright light reflects off of a shiny surface. The light appears to bleed out into the surrounding air. Bloom is only available in the shader-based drivers such as ``DirectX11`` and ``OpenGL2``. Bloom is enabled using the ``HPS::PostProcessEffectsKit``.

.. tabs::

	.. group-tab:: C++
	
		.. literalinclude:: ../../../internals/tests/docs/source/cpp/00730_tutorial3_1.cpp
		   :start-after: //! [ppe]
		   :end-before: //! [ppe]
		   
	.. group-tab:: C#

		.. literalinclude:: ../../../internals/tests/docs/source/cs/00730_tutorial3_1.cs
		   :start-after: //! [ppe]
		   :end-before: //! [ppe]

.. image:: images/03/t.3.1.e.png

*The shiny parts of the turbine create an interesting effect when bloom is enabled*


.. _0305:

3.5 Texturing
=============

For the highest amount of visual quality, you'll also want to add textures. Applying textures to a model as complex as the turbine is beyond the scope of this tutorial, but an image is provided to demonstrate it. You can find the textured model in the *samples/data* directory in your HOOPS Visualize Desktop installation. More information on textures can be found in the :doc:`textures </prog_guide/0503_textures>` section of the Programming Guide and in :doc:`Tutorial 2: Applying materials <02_applying_materials>`.

.. image:: images/03/t.3.1.f.png

*The turbine with textures applied*
