since i've noticed that many people here are quite clueless when it comes to a:m internal materials (no offense intended - for a long time i was too), i'll try to start a Tutorial series.
The following tutorial is by no means a final version.
Currently its just a collection of facts around materials, i'd like to hear your comments, additions and discussion. Hopefully it will productive - when it is, i (or someone else) shall merge all important info posted in this thread.
Tutorial: Building Materials Part I
This tutorial is targeted towards "material beginners". No prior knowledge is needed of materials, but you should be familiar with models, groups, the pws (project work space) and rendering.
To create a new Material, double-click on the "Materials" folder in the pws:
1. A window showing the new Material will pop up, we'll call it the "preview window" here.
By clicking/dragging on the preview window you can move the preview light source. This is important as it also forces a:m to refresh the preview window with a fine resolution render. You can also apply all basic A:M camera movements here: [T]urn, [M]ove, [Z]oom (also with the middle mouse button plus modifier keys).
2. A new Material will be created under the Materials folder.
Basically all A:M Materials are containers for Attributes.
Each of those Attributes can be either Plug-In or a Native Attribute, we'll call this the Attribute Type. You can change the Type by right-clicking the Attribute and selecting something from the menu.
3. The new Material will have one Native Attribute.
Native Attributes contain all A:M surface Properties. You can change most of these Properties with drag operations on the value at the right, but also by clicking on the value and inputting a number (or color).
You can add new Attributes to the Material by selecting that option from the Materials right-click-menu.
The order of these Attributes is important.
When A:M renders a pixel, it will go though the Attributes from top to bottom and collect information about the Properties of that pixel (like color, but also specularity, ambiance, transparency, reflectivity, and others). When it has processed all Attributes, it will use the collected "surface Properties" to calculate the final color of this pixel.
Exercise 1:
Create a new Material.
Set the Attributes color to blue.
Add a second Attribute.
Set its color to green.
You'll notice, that the second Attribute has priority over the first.
But an Attribute can also just leave alone certain Properties. This will be indicated by a "not set" next to the Property name.
Exercise 2:
Create a new Material.
Set the Transparency Property of the Attribute to 50%.
Add a second Attribute.
You'll notice, that the preview shows the object as transparent, even though there is a second attribute after the first. This is due to the "not set" value of the Transparency Property in the second Attribute.
Materials can be applied (drag&drop) to Models or Groups.
You can apply multiple Materials to one Model or Group.
A:M handles this just like multiple Attributes in a Material:
The Attributes of the above Material are processed first, the Attributes of the bottom Material are processed last.
Since Groups are part of a Model, both, Materials on the Model and Materials on the Group will contribute to a groups look.
The Materials on the Model will be processed first.
Exercise 3:
Create a simple model consisting of 3 cubes.
Select each of the cube and name the selection ("cube 1", "cube 2" and "cube 3").
Drag the green Material from exercise 1 onto the Model.
Drag the transparent Material from exercise 2 onto the Group "cube 2".
You'll notice that all of the cubes are green, but the second is transparent too.
This is a great tool to build diverse texturing for Models - have a basic material and give it variation by adding certain Properties to parts of the Model.
Another tool for this variation are Group Properties.
It basically works as a first, invisible material on the group. I usually leave those alone though, because having all Materials in one place (the Materials folder) has big advantages.