Thea Materials

The material system is the most important and complicated concept in a render engine. Since materials define how light interacts with objects, sometimes they can be highly knowledge-demanding in order to simulate correctly all effects that take place. Thea Materials have been designed in a way making them capable of describing every aspect of this interaction. They are well integrated inside Cinema 4D and they allow users to design the desired behavior with flexibility producing correct photorealistic results. In this section we will describe the workflow to design Thea materials inside Cinema 4D.

Create a new Thea material

Thea Material can be created either using presets or Thea Content Browser.

Preset Menu

To create a preset material, go to Material Manager (by default in bottom left of your Cinema 4D) and select any material in Thea menu. This list contains the most common materials and they can be used as basis for any material you require. You also have the option to select the "Empty" preset, which will allow you to create a material from scratch.

Content Browser

The other option you have to create a Thea Material is by using the Content Browser.
Content Browser points directly into the Material folder of Thea Render Data directory. In any case, if you have your own libraries, you can just right-click the Custom Materials group and add any folder with Thea Materials in your disk. The folder will be added in content browser and the hierarchy tree will be extended. You can also remove a custom folder by right-clicking it and selecting "Remove Custom Folder"

Editing Thea Materials

Thea Materials have the same workflow as Cinema 4D Materials. You are able to add or remove Layers and modify their parameters in their corresponding tab.
First of all, in the material interface, you can see the Preview, the Material Schema, utility buttons and the properties from the selected tab. Another way to edit your material is via Material Editor. You can launch it by double-clicking the material.

Basic Tab
In Basic tab, you can activate the layers and components, which will give physical properties to the material. Activating a layer or component, its corresponding tab will appear that contains the layer/component parameters.

General Tab
Here, you can find the global material settings. The following properties appear only if you use Adaptive BSD: Perceptual Level, Tracing Depth, Min Blurred Subdivs and Max Blurred Subdivs.

Animated Textures parameters allows you to enable the animation in your bitmaps. After enabling this parameter, go to any Bitmap Shader in this material and add an image with a number in its name (e.g. effect_0000.jpg). Of course, the rest of the frames have to be in the same folder (effect_0001.jpg, effect_0002.jpg, effect_0003.jpg etc.). Click the shader for more options and in "Animation" tab click "calculate". Animated textures are refreshed in every frame in the Darkroom's IR and in Picture viewer but not in the viewport (unless you refresh the material manually). The mode "Ping-Pong" is not supported yet.

Layers

Basic: It is the most common Layer since it contains Diffuse, Reflectance and Translucency properties.
Glossy: It is used for its reflection and refraction properties.
SSS: SSS is based on Bidirectional Subsurface Scattering Distribution Function model that is used to describe the light interaction through the media.
Thin Film: This glass model is used for its reflection and transparency properties.
Coating: This layer is applied on top of the other layers to add Specular properties on the object.

Components

Clipping (Alpha): Clipping is used to cut the material based on a given texture.
Displace: This component causes the geometric position points to be displaced based on a texture or a height map.
Emitter: It is used to create area lights in your scene. Once applied in any object, it will distribute light based on the surface. In Thea Render v2.0, point lights and area lights support Custom Light Evaluation for Diffuse, Translucent, Reflectance, Transmittance and Medium SSS surfaces. That means you can control the emitter's contribution on objects based on the selected layers.
Medium: This component is used by Thea Render's workflow to apply volumetric scattering on entities.

Example

Create an object with emitter material and in Custom Light Evaluation parameters disable Diffuse.
Then create a Thea Material with Basic Layer activated. Set its Diffuse color parameter to red and apply the material to any object.
You'll notice that since the emitter has its Diffuse evaluation disabled, the object is not affected by it.

Stacking Layers

You will notice that as you add more layers in your material, the Material Schema will be updated as well. In material schema you can either add new layers or manage the existing ones regarding their stacking status. As we have said above, you can add new layers by switching to Basic tab and enable the ones you want. Alternatively, you can add new layers by clicking the 5-layer buttons on the right of the Material Schema.
The buttons on the top of Material Schema are used to either stack up or down a layer or to delete it.
Simply, click the layer you want to modify and any of the 3 buttons.

Buttons
Refresh: Recalculates the material's preview.
Load: Loads .mat.thea files into the selected Thea Material inside Cinema4D.
Saves: Saves the selected Thea Material in .mat.thea and *.mat.pack format.