Material Editor:

The UDK material editor, is essentially a visual system for writing shader programming.
All the work you do, becomes shader code.  This is CGFX, GLSL, or HLSL shader code
(depending on platform)
You can also write code yourself. (Discussed later in the custom code section.)
This code in turn gets compiled to lower level code, and eventually machine code.

This allows the video card to handle many complex tasks, video cards are super fast
so this is great.





Click on nodes to select them, hold ctrl and LMB drag to move them.
Ctrl+Alt+LMB drag will draw selection marquee window
Selected nodes show up as yellow

Up at the top you can click sphere, cube, and cylinder buttons to see different previews


Click a node to select it and it's properties show in the bottom left window
Change options for each node there
Selecting no nodes shows material properties


You can plug nodes together by dragging between them
Alt+LMB click to disconnect attributes


Material Inputs (most important):
  Diffise is similar to color in Maya
  Normal is similar to bump in Maya
  Emissive is similar to incandecense in Maya
  Specular is similar to specular color in maya
  Specular power is similar to ecentricity on a blinn in maya




Useful nodes:


  Constant
    A constant is just a number
    To create
      Hold 1 on keyboard, and click in black space
      RMB > Constants > New Constant
      Find in list on top right and drag it into graph

    A constant can also be used for a greyscale color
   
    White is 1  (photoshop white, 255)
    Black is 0  (photoshop black, 0)
    50% Grey is 0.5 (may not appear like 127 in photoshop)
      color profiles and human perception affect these things
     
     
    Anything above 1 as potentially glowing, so bright a halo of light forms around
      the default in UDK is to bloom (glow) bright pixels
     
  Constant3Vector
    A Constant3Vector is just 3 numbers side by side, (a group of 3 numbers)
      usually a color
      can also store a position, a rotation, or something else
     
      double click to edit the color value
     
      To create:
        Hold 3 on keyboard, and click in black space
        RMB > Constants > New Constant3Vector
        Find in list on top right and drag it into graph
   
   
      Using constant3Vectors for material properties is like just changing colors in Maya
   

  Multiply
    Multiplies one input by the other input
    For color/textures works like photoshops "multiply" layer blending
    You can use multiply to tint, brighten, or darken
    Most common math node

    To create:
      Hold M on keyboard, and click in black space
      RMB > Math > Multiply
      Find in list on top right and drag it into graph   

    Make normal maps stronger weaker
      multiply a normal map by a constant3
        r=1,g=1,b=1
        turn blue up (5) for a weaker normal map
        turn blue down (0.2) for a stronger normal map
 
 
 
 
Material Instances

  Material instances are easy ways to duplicate/instance existing materials
    and adjust them (in real time).

  To create a material instance:
    RMB click on material in the content browser
      Create New Material Instance (Constant)

  Applied to objects just like any material