Tutorial One
A Simple Rusty Object
This tutorial is intended to provide a simple example of creating a rusty object using Enhance:AM. In the tutorial the only texture used is AM_fBm which can be downloaded for free. Just follow the links to the respective demo sections, depending on your AM version, from Enhance:AM Home Page

Introduction
In this tutorial we are using the AM_fBM texture. This is a fully 3D texture based on Fractal Brownian Motion which basically means it is a noisy fractal texture. The texture function is therefore basically a noise function varying from 0% to 100%. In Enhance:AM the texture function is mapped to a color map to color the object, to bump height to create bump surfaces and to an alpha map which can control the object other attributes. The color map is a collection of up to eight colors with up to eight blend points. The easiest color map to imagine is setting the first color to black and the second to white. Then, by setting the first blend to 0% and the second to 100% we are saying "Based on the texture function color the object using a blend from black where the texture function is 0% to white where the texture function is 100%". This example can be seen on the right. The alpha map works in the same way except that it uses single values rather than colors. This creates a channel that can then be used to control the object's other attributes like transparency. This concept is very important to the following tutorial particularly when considering the color maps and alpha maps used to control the application of the rust. More details about AM_fBm can be found at The AM_fBm Manual Web Page

Step One - The Basic Scene
Create a new project using the default set up and add your favorite object. First, we are going to create a basic shiny steel object using the standard attribute settings so create a new material and bring up the properties for the basic attribute. Set the diffuse color to 130,140,150 to give the ball a steel blue/grey color. Then set the Specular Size to 20% and the Specular Intensity to 50% to give the steel a small highlight. To finish off set the Reflectivity to 30%. Your object should now look something like the ball shown to the right.

Step Two - Basic Dinks
Next we are going to add dinks to the surface of the object so add a new attribute to our steel material and change its type to the AM_fBm plugin from the AM_Noise series. Ensure that the AM_fBm texture appears below the basic steel attribute in the material list. Bring up the properties for AM_fBM and open up the Axis section. Here set the scale to 8,8,8 for X,Y and Z. Then go to the Color Map section and turn all the Enable Color switches to OFF. You should now have a lumpy steel object. Now we are going to clip these bumps so go to the Bump section. Here set the Top Clip to 50. This means that bumps where the texture function is greater than 50% in height are not drawn leaving the object smooth. If you render now you should see a smooth object with noisy dinks. Finally, as the dinks are to become rust we want to up the detail on the dinks so go to the Parameters section and make the Function Increment 30 The AM_fBm Manual Web Page about how this works). Your object should now look like the one shown on the right.

Step Three - Making Rust
We now want to make the dinks become rust by coloring them. Rust color basically goes from dark brown to orange so go to the Color Map section and set Color1 to 128,64,0 a medium brown. Then set Color2 and Color3 to 255,128,0 a medium orange. As we want Color1 and Color2 to be used to color the dinks and we want the underlying steel color to show through as well set only the Enable Color1 and Enable Color2 switches to ON. The last thing to do is adjusted the color blending so that dinks are mostly brown and go orange at the fringes and finally a steel color on the smooth parts. The easiest way to do this is using the interactive preview. This means that you can see the updates as you make them. To adjust the colors go to the Blends section. Here set Blend1 to 30%, Blend2 to 50%, Blend3 to 70% and Blend4 to 100%. Now, what we have set up is Color1 is brown and Color2 is orange. Color3 and Color4 are switched off so that the steel color shown through. The texture function is mapped to these colors based on the blend points. This means that the valley of the dinks will be brown until the texture function reaches 30%. It will the blend brown to orange until the texture function reaches 50% when it blends to the underlying steel color until 70%. Beyond this the underlying steel color is shown, full on. This result is the object being textured like the picture to the right.

Step Four - Making The Rust Right
The observant amongst you will notice two problems. Firstly, the rust is reflective and secondly it has a specular highlight. What we want is the rust to be non-reflective and dull. In order to control the object's attributes to achieve this we will create an alpha map. An alpha map works much the same way as the color map described above except that its a single channel that can be used to control any of the object's attributes like reflectivity. Go to Alpha Map section and set Alpha1 and Alpha2 to 100%. This means that what ever attribute will choose to control will be controlled where the object is rusty as the alpha map uses the same blend points as the color map and colors 1 and 2 are what colors the rust. We want to make rust non-reflective so go to the Affect Others section and make the Reflectivity 0% and switch the Affect Reflectivity enable switch to ON. What we are actually doing here is forcing the reflectivity to 0% where the alpha map is 100%, i.e. where the rust is, and not affecting it where the alpha map is 0%, i.e. where the steel shows through. In the same way the Specularity can be switched off for the rust areas by going to the Affect Specularity section and setting the Specular Size and Specular Intensity both to 0% and switching the Affect Specular Size and Affect specular Intensity enable switches to ON. The final texture should look something the picture on the right.

Step Five - Experimentation
Of coarse, it doesn't stop there. All of the parameters we have set up can be changed, adjusted and modified. By changing the blend points the object can be made more or less rusty. They can be animated to make the ball rust over time. A dirt layer can be added using a second instance of AM_fBm. You can change the colors to make the rust mould or even make it glow like some strange fungus.


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