Shader Basics

After modeling a scene you can apply attributes such as color, texture, transparency, and reflectivity to objects to achieve photo realistic results. These attributes are created using shaders to create realistic looking materials to assign to objects. Shaders are kept in the Multilister, an important window that displays shaders, lights, or forces, or all of these at the same time. The shader mode of the Multilister is used in this lesson as you begin working with shaders and their various parameters.

In this lesson, you create shaders for all parts of a fruitbowl model and assign these shaders to the objects.  First, download the following files:

Initial Setup
A file has already been prepared containing the fruitbowl model. Start by opening it and performing a quick render.

   Open Maya and creating and open the scene
   1. Select File->Open 
   2. From the Maya file menu, select fruit.mb
  

A perspective window is displayed showing a bowl on a tabletop containing an apple, a banana, and an orange.

   Smooth Shade the Scene
   3. Press and Hold the space bar on you keyboard to bring up the marking menus.
   4. From the shading menu, select smooth shade all. All the objects are rendered in
       gray to show that they are using the Maya default shader.

Creating and assigning a new shader.

   Next you create a shader for the apple.
   1. Select the Rendering menu set from the drop down box in the upper left
      corner of the Maya status bar.
   2. From the Windows menu, select Rendering Editor->Multilister. This will bring up the
      multilister. The Multilister contains information about the shaders
      textures, lights, and cameras in you scene. The menus at the top contain
      relevant shader functions.

   Make a new shader
   3. Select Create from the edit menu in the Multilister.
   4. Select Phong from the CreateRenderNode box, and then select the close
       button to close the box.

   Rename the new shader
   4. double-click on the default phong1SG shaders name and press the backspace
       key to clear the existing text.
   5. Type AppleSG and press enter.

   Note: Both mixed case and lower case names are used for shaders in this series of lessons.

   Pick the apple object
   6. Make sure the AppleSG shader icon has a orange border to indicate that it is
       the only active shader.
   7. Select the apple from the bowl of fruit. Once you select the apple, you should
       see the apple object appear in the channel box.

   Assign the shader to the object
   8. With both the AppleSG shader icon and the apple object active, select Edit->Assign
        from the Multilister menu to assign the shader to the apple.

   Note: You can also create shaders and not assign them to objects. However only assigned
             shaders are displayed when you render the scene.

   Editing Shader Parameters
   You can edit some of the shader parameters to create the look you want using the Shader and Color editors.

   Open the shader editor
   1. Double-click the AppleSG shader icon to open the shader editor.
   2. In the Common Material Attributes  section, click once on the gray color
       sample next to the Color parameter to open the Color editor.

   3. In the Color editor, drag the R slider to 1, and the G and B sliders to
       0. This changes the Red, Green, and Blue values to define a new red
       color.

    Notice that the Apple shader icon in the Multilister has turned Red. In
    another lesson, you will make this shader even more realistic by adding
    a texture map.

   4.  Expand the Specular Shading box and change the Cosine Power parameter to 5.0 . 

    Keep the two editors open while you proceed.

    Copying a shader
    1. With the Apple shader active, select Edit->Duplicate->Shading Network
        from the Multilister menu. This creates a copy of the Apple Shader
        Group.
    2. Double-click on the name AppleSG1, clear it, and type OrangeSG to rename       it.

    Assign the orange shader
    3. With nothing picked, select in orange object located in the fruitbowl.
    4. With both the OrangeSG shader and Orange object active, select
        Edit->Assign, to assign the shader to the Orange.

    Edit the Orange Shader's reflectivity and shininess
    5. Double-click on the Cosine Power value in the shader editor and change
        it to 15, to make it less shiny than the apple. Oranges are not as
        reflective as apples, so change the Reflectivity value to 0.1.

    Edit the shader's color
    6. In the color editor, click on the value next to G and type 0.55 to
       change the color to Orange.

   Creating the Banana shader

    Create and name a new shader
    1. Select Edit->Create from the Multilister menu.
    2. Select Phong, and click the close button to close the CreateRenderNode
       dialog.
    3. Rename the shader BananaSG.
    4. In the BananaSG Color editor, change the RBG values to 1, 0.843, 0.275
    5. In the BananaSG attribute editor, change the value of the Cosine Power
        to be 5, and the value of the Reflectivity to be 0.1.
    6. Assign the shader to the Banana.

    Create the Table shader

    Create and name a new shader
    1. Make sure that all of the geometry in the scene has been deselected. Then click on the
        Apple shader in the Multilister to select it.
    2. Select Edit->Duplicate->Shading Network
    3. Double Click on the AppleSG1 name and clear it. Type TableSG and press
        enter.

    Edit the shaders color
    4. Double click on the shader icon to bring up the shaders Attribute
        Editor.
    5. In the TableSG color editor, change the Red value to 0, and the
        green value to 0.2.

    Assign the Shader
    6. Make sure the TableSG shader is highlighted with the orange box, and
        then select the table from the scene.
    7. Select Edit->Assign to assign the shader to the object.

    Create the Bowl Shader
    1. Make sure that nothing is selected in your scene.
    2. Click on the Apple shader in the multilister to select it.
    3. Select Edit->Duplicate->Shading Network
    4. Rename the shader to BowlSG.

    Edit the shader attributes
    5. In the color editor, change the value of the color to 0.11 for Red,
        0.11 for Green, and 0.055 for Blue.
    6. In the transparency editor, change the value to 0.56 for Red, 0.878 for
        Green, and 0.498 for Blue.
    7. Adjust the diffuse value to 0.150.
    8. Adjust the Specular color to 0.93 for both the Red, Green, and Blue
        components, and adjust the reflectivity field to 0.148

    Assign the Shader to the Bowl
    9. With the BowlSG shader group selected, pick the bowl inside of maya.
    10. In the Multilister select Edit->Assign to assign the shader to the
          bowl.

There are now eight shader icons in the Multilister: AppleSG, BananaSG, BowlSG, InitialParticle, InitialShader, InitialGlow, OrangeSG, TableSG.
If there are more shaders listed than you can see, use the scroll bar at the left of the Multilister window, or resize the window by dragging at the
corners. You can also change the icon display to list by name or as columns by selecting the display method you wish under Display->as List, or Display->as Columns.

To see the objects and surfaces an active shader is assigned to, select Select->Select Assigned. Your perspective window should now look like the following:


 
   Rendering your image:
        You will now render your completed fruit scene.
        1.  Change the menu set to Rendering by pressing F5.
        2.  Select Window->Render Globals.
        3.  Change the image format to SGI.
        4.  Expand the Resolution options, and change Resolution to 640x480.
        5. Close the Render Globals window.
        6. Render your scene by selecting Render->Render into new Window.


     Save the model
    1. From the File menu, select Save scene as. Save the scene as myfruitbowl2.