Creating Semi-Transparent, SSS, Veiny Wing-Skin
The Cycles Rendering Engine in Blender has many unique qualities that tend to set it apart from other Non-Realtime 3D Renderers such as the ability to visualize a Render within the 3D Viewport, an intuitive vitalization of a Material Node Network that also extends into Post-processing and a carefully considered balance between Biased and Non-biased rendering characteristics. However, what really seems to be most intriguing about Material/Shader set-ups in Cycles is probably one of it’s most communally underrated features, that being, it’s unique approach to isolating Surface Geometry for Shader set-ups.
Masks in Cycles serve the purpose of isolating parts of an image during Compositing or, as in the case of the image above, isolating parts of the geometry that make up a model’s surface.
If you have ever worked with Layer Masks in Photoshop or the GIMP, the concept might be easy to imagine. Nonetheless, the process of setting up a Mask in Cycles is so trivial that it warrants very little explanation. This could account for why the simplicity of this approach which disguises a full-featured arsenal of infinite, pixel-accurate, Shader combinations seems only to be reserved to passing asides in numerous online tutorials discussing Shader setups.
The above image depicts a typical set-up using masking with Cycles Nodes. Although this set-up results in a simple Shader that fades from one Diffuse Color to another, the simplicity and level of control necessitated when generating Shaders with Cycles for more complex Networks are principally similar.
For Example, the following image depicts how this masking technique can be used to isolate the veins on the Vampiro’s wings which require a different Shader to the rest of the wing.
In this case a Mask is used to balance a seemingly paradoxical requirement,
- In order to separate the Veins from the rest of the wing a different color is used to boost their presence.
- However, the deviation from the rest of the wing’s main color palette has the side-effect of causing the veins to look unintegrated in their default state.
As a result masking provides an ideal solution which allows for blending one Shader with another and controlling the effect with varying levels of grey, while maintaining modular editability within the Shading Network.
Although this mask might take some time to create, it’s application within the Shading Network allows a great deal of control over the final result and can be used in varying combinations within other sub-shader networks.
As mentioned earlier the simplicity of this masking technique seamlessly underlies the complexity of it’s ability to create a relationship between potentially unrelated physical properties such as Transparency and SSS (Sub-surface Scattering), Glossiness and NPR (Non-Photo-Realistic renders) to name a few of the infinite possibilities of Shading Network combinations. Subsequently it is worth bearing in mind that although the current Shading Network being discussed combines two SSS Shaders, blending Shaders of similar type is certainly not an inherent limitation of the technology, but used here simply as an approach to an aesthetic.
In this case the mask’s prominent white areas will boost the presence of the vein’s SSS Shader and the smaller veins (in varying scales of grey) serve the purpose of reintegrating the veins back into the SSS Shader consisting of the wing’s main color palette.
The above image depicts a single Texture node that is used for the Color input on both SSS Shaders, however the color is modified for the veins.
A Mask is then used to create a blend between the differentiating color palettes and physical properties of the two Shaders via a Mix Shader. This unique Shader, in itself, provides an output that can subsequently be used for combining the resultant Shader within other sub-shader networks.
In conclusion the benefit of this method, besides the simplicity in approach, is an editable Mask that both boosts and blends the offset color from and into the main texture colors. Furthermore, editing the color of the Veins through the RGB Curves Node does not require external software and as the process is internal there is no tedious reintegration required within the Shading Network.