Creating a gray alien skin material with procedurals

In this recipe, we will create a gray alien-like skin shader as shown in the following screenshot, using Cycles procedural textures:

Creating a gray alien skin material with procedurals

The alien Suzanne as it appears in the final rendering

Getting ready

Start Blender and open the 9931OS_08_alienskin_start.blend file, where there is an already set scene with an unwrapped Suzanne primitive object.

The Suzanne_unwrapped_alien mesh has been modified by a shape key, to morph its monkey features into the head of a gray alien–like creature; in fact, in the Object data window, under the Shape Keys subpanel, there are the alien shape keys, with Value of 1.000; sliding the slider towards 0.000 gradually restores the original Suzanne shape.

The Suzanne mesh also has a Vertex Colors layer named Col and is obtained by the Dirty Vertex Colors tool.

On the second layer, there are two Planes tracked (by a Damped Track constraint, in the Object Constraints window) to the Camera to stay perpendicular to its point of view; the star_backdrop object is used to create a simple star backdrop for our alien Suzanne, and the star_backdrop.001 object is used simply to create something to be reflected by the alien-like Suzanne's eyes.

Press Shift + F1 (or go through the File | Append main menu) to append the SSS_group node from the 9931OS_07_SSS_ngroup.blend file.

How to do it...

Let's start by first setting the background image material using the following steps:

  1. Select the star_backdrop Plane and click on the New button in the Node Editor window toolbar or in the Material window. Rename the material star_backdrop, and in the Material window, switch the Diffuse BSDF shader with an Emission shader. Set the Strength to 0.500.
  2. Add an Image Texture node (press Shift + A and navigate to Texture | Image Texture) and connect the Color output to the Color input socket of the Emission node. Click on the Open button and browse to the textures folder and load the centre-of-milky-way_tile_low.png image.
  3. Add an RGB Curves node (press Shift + A and navigate to Color | RGB Curves) and paste it between the Image Texture and Emission nodes. Click on the curve window to add a control point and set these coordinates: X to 0.36667 and Y to 0.12778. Click again to add a second control point and set these coordinates: X to 0.65556 and Y to 0.81111.
  4. Add a Mix Shader node (press Shift + A and navigate to Shader | Mix Shader) and paste it between the Emission and Material Output nodes; switch the connection that comes from the Emission node to the second Shader input socket of the Mix Shader node; leave the first Shader input socket empty.
  5. Add a Light Path node (press Shift + A and navigate to Input | Light Path) and connect the Is Camera Ray output to the Fac input socket of the Mix Shader node.
  6. Go to Outliner and select the star_backdrop.001 object; click on the double arrows icon to the left side of the data block name (Browse Material to be linked) in the Node Editor toolbar, and select the star_backdrop material; click on the 2 icon button to make it single-user.
  7. In the new star_backdrop.001 material, select the Mix Shader node and press Ctrl + X to delete it and keep the connection; then, also delete the Light Path node.
  8. Go to the Object data window, and in the Ray Visibility subpanel, uncheck all the items except for the Glossy one.

    Now, let's get started with the creation of the alien skin shader (also with a different material for the eyes).

  9. Select the Suzanne_unwrapped_alien object; click on the New button in the Node Editor window toolbar or in the Material window, and rename the material alienskin.
  10. Go into Edit Mode, select the eyes vertices, and click on the + icon on the right of the Material window to add a second material. Click on the New button and rename the material as alieneyes; then, click on the Assign button to assign it to the selected vertices. Go out of Edit Mode.
  11. Switch the Diffuse BSDF shader with a Mix Shader node; in the first Shader slot, select a Diffuse BSDF shader, and in the second one, select a Glossy BSDF shader. Set the Mix Shader node's Fac value to 0.600 and the Diffuse BSDF node's Color values for R to 0.010, G to 0.006, and B o 0.010; set the Glossy BSDF node's Distribution to Beckmann, change the Color values for R to 0.345, G to 0.731, and B to 0.800, and change the Roughness value to 0.100.
  12. Select the alienskin material, and in the Material window, switch the Diffuse BSDF shader with an Add Shader node (label it as Add Shader1); in the first Shader slot, select a Mix Shader node, and in the second one, load the appended SSS_group node. In this node, set the Contrast value to 3.000 and change the Color values for R to 0.834, G to 0.263, and B to 0.223.
  13. Go to the Mix Shader node, and in the first Shader slot, select a Diffuse BSDF node, and in the second one, select a new Add Shader node (label it as Add Shader2). Set the Diffuse BSDF node's Roughness value to 0.800.
  14. In both the Shader slots of the Add Shader2 node, select a Glossy BSDF shader node; label the first one as Glossy BSDF 1 and the second as Glossy BSDF 2; set Distribution of both to Beckmann, and then set the Roughness value of the first one to 0.600 and that of the second one to 0.300.
  15. Add a Fresnel node (press Shift + A and navigate to Input | Fresnel) and connect its output to the Fac input socket of the Mix Shader node. Set the IOR value to 1.300, as shown in the following screenshot:
    How to do it...

    The basic shader network with the SSS provided by the appended node group

    Now that we have set the basic shader for the alien skin, let's set an important component of the material, that is, the bump, by following these steps:

  16. Add a Texture Coordinate node (press Shift + A and navigate to Input | Texture Coordinate) and two Mapping nodes (press Shift + A and navigate to Vector | Mapping); connect the UV output of the Texture Coordinate node to the Vector input socket of both the Mapping nodes, labeled as Mapping1 and Mapping2 respectively.
  17. Set the Rotation value of Y of the Mapping1 node to 60°; set the Rotation value of Y of the Mapping2 node to 20°.
  18. Add two Voronoi Texture nodes (press Shift + A and navigate to Texture | Voronoi Texture) and label them as Voronoi Texture1 and Voronoi Texture2. Connect the Mapping1 node output to both their Vector input sockets. Set the Scale value of the Voronoi Texture1 to 100.000 and the Scale value of the Voronoi Texture2 to 20.000.
  19. Add two Wave Texture nodes (press Shift + A and navigate to Texture | Wave Texture) and label them as Wave Texture1 and Wave Texture2. Connect the Mapping1 node output to the Vector input socket of the Wave Texture1 node. Set the texture Scale value to 20.000, Distortion to 10.000, Detail to 16.000, and Detail Scale to 0.300.
  20. Connect the Mapping2 node output to the Wave Texture2 node's Vector input socket, and set all the texture values exactly as in the previously described one.
  21. Add a Noise Texture node (press Shift + A and navigate to Texture | Noise Texture) and label it as Noise Texture1. Connect the Mapping2 node output to its Vector input socket, and set the texture Scale value to 120.000 and the Detail value to 7.000.
  22. Add a ColorRamp node (press Shift + A and navigate to Converter | ColorRamp), label it as ColorRamp1, and connect the Voronoi Texture1 node's Color output to its Fac input socket. Set Interpolation to Ease and move the white color stop to the 0.126 position.
  23. Add a Math node (press Shift + A and navigate to Converter | Math), change Operation to Multiply, and label it as Multiply1. Connect the Color output of the ColorRamp1 node to the first Value input socket of the Multiply1 node, and set the second Value to 0.050.
  24. Add a MixRGB node (press Shift + A and navigate to Color | MixRGB) and connect the Color output of the Voronoi Texture2 node to the Color1 input socket, and the Color output of the Wave Texture1 node to the Color2 input socket. Set Blend Type to Difference and the Fac value to 1.000, and then label it as Difference1.
  25. Add a second MixRGB node (press Shift + A and navigate to Color | MixRGB) and connect the Color output of the Voronoi Texture2 node to the Color1 input socket, and the Color output of the Wave Texture2 node to the Color2 input socket. Again, set the Blend Type to Difference and the Fac value to 1.000 and label it as Difference2.
  26. Add two ColorRamp nodes (press Shift + A and navigate to Converter | ColorRamp), and label them as ColorRamp2 and ColorRamp3; connect the Difference1 node output to the Fac input socket of the ColorRamp2 node, and the output of the Difference2 node to the Fac input socket of the ColorRamp3 node.
  27. Set Interpolation to B-Spline for both of them, and for both of them, move the white color stop to the 0.255 position.
  28. Add a MixRGB node (press Shift + A and navigate to Color | MixRGB) and connect the Color output of the ColorRamp2 node to the Color1 input socket and the Color output of the ColorRamp3 node to the Color2 input socket. Set the Blend Type to Multiply and the Fac value to 1.000. Label it as Multiply2.
  29. Press Shift + D to duplicate the Multiply1 node and label the duplicate as Multiply3. Connect the output of the Multiply2 node to the first Value input socket of the Multiply3 node. Set the second Value to 0.050.
  30. Press Shift + D to duplicate the Multiply3 node and label the duplicate as Multiply4. Connect the Color output of the Noise Texture node to the first Value input socket of the Multiply4 node, and set the second Value to 0.175.
  31. Add a Math node (press Shift + A and navigate to Converter | Math) and label it as Add1. Connect the output of the Multiply1 node to the first Value input socket and the output of the Multiply3 node to the second Value input socket.
  32. Press Shift + D to duplicate the Add1 node and label the duplicate as Add2; connect the output of the Add1 node to the first Value input socket and the output of the Multiply4 node to the second Value input socket.
  33. Add a Bump node (press Shift + A and navigate to Vector | Bump) and connect the output of the Add2 node to the Height input socket of the Bump node; set its Strength value to 4.000 and connect its Normal output to the Normal input sockets of the Diffuse BSDF node, of the two Glossy BSDF nodes, and of the SSS_group node, as shown in the following screenshot:
    How to do it...

    The apparently complex bump network to be connected as per the shader bump

    We are done with the bump part, so now, let's set the color pattern using the following steps:

  34. Add a ColorRamp node (press Shift + A and navigate to Converter | ColorRamp), label it as ColorRamp4, and connect the Color output of the Multiply2 node to its Fac input socket. Set Interpolation to Ease and move the black color stop to the 0.495 position, and the white color stop to the 0.000 position.
  35. Add a MixRGB node (press Shift + A and navigate to Color | MixRGB), set the Blend Type to Add, and label it as Add3. Connect the Color output of the ColorRamp4 node to the Fac input socket and set the Color2 values for R to 0.553, G to 0.599, and B to 0.473.
  36. Add a Noise Texture node (press Shift + A and navigate to Texture | Noise Texture) and label it as Noise Texture2. Connect the Mapping1 node output to its Vector input socket and set the texture's Scale value to 60.000 and the Detail value to 7.000.
  37. Add a ColorRamp node (press Shift + A and navigate to Converter | ColorRamp), label it as ColorRamp5, and connect the Noise Texture2 color output to its Fac input socket. Set Interpolation to B-Spline and move the black color stop to the 0.486 position and the white color stop to the 0.771 position.
  38. Press Shift + D to duplicate the Add3 node, label the duplicate as Add4, and connect the Color output of the ColorRamp5 node to its Fac input socket; connect the output of the Add3 node to the Color1 input socket and set the Color2 values for R to 0.235, G to 0.198, and B to 0.132.
  39. Press Shift + D to duplicate the Add4 node, label the duplicate as Overlay, and change Blend Type to Overlay as well. Set the Fac value to 1.000 and connect the output of the Add4 node to the Color1 input socket.
  40. Add an Attribute node (press Shift + A and navigate to Input | Attribute) and connect its Color output to the Color2 input socket of the Overlay node; in the Name field, write Col (the Vertex Colors layer).
  41. Connect the output of the Overlay node to the Color input socket of the Diffuse BSDF shader node.
  42. To make them more easily readable, frame the three groups of nodes, SHADER, BUMP, and COLOR, as shown in the following screenshot:
    How to do it...

    The simpler color pattern to be connected only to the Diffuse shader node and the nodes grouped by frames

  43. Save the file as 9931OS_08_alienskin_final.blend.

How it works...

  • From step 1 to 8, we built a simple and quick shader for the starry background and for the Plane in front of the Suzanne_unwrapped_alien mesh to be reflected in the eyes; note that the background Plane material works as a shadeless material. To see how to set a bright but not emitting light background, that is, a shader that behaves as the shadeless material you have in the Blender Internal engine, go to Chapter 9, Special Materials.
  • From step 9 to 15, we built the basic shader for the alien Suzanne's skin; the diffuse component is mixed and modulated by the Fresnel output, with a specular component made by two summed Glossy BSDF nodes with different roughness values, so as to have a crisper specular effect on a more diffuse one, and with the additional help of the SSS_group node to simulate a reddish Subsurface Scattering effect.
  • From step 16 to 33, we built the quite complex bump pattern for the skin by mixing the outputs of three different types of procedural textures with the help of both the Math and MixRGB nodes, and the variations provided by the ColorRamp nodes.
  • Finally, from step 34 to 41, a simple grayish color pattern is modulated through the Dirty Vertex Colors layer data that comes from the mesh and that uses the first part of the bump pattern to add variation.
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