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'The Official Luxology modo 301 Guide': Shader Tree Fundamentals

In this third excerpt from The Official Luxology modo 301 Guide, author Daniel Ablan puts a twist on Shader Tree applications.

All images from The Official Luxololgy modo Guide, Version 301 © Course Technology.

This month, VFXWorld continues excerpting a series from the Thomson Course Technology book The Official Luxology modo 301 Guide, which will give VFXWorld readers a chance to build, layer, model, animate, texture and render with modo. Skills are taught using projects that take the reader from simple modeling to complex tasks, taking advantage of various tools and options along the way.

In Chapter 6, you modeled something a little untraditional in a corkboard with Post-it Notes. While most projects work through modeling a full 3D object, it's a good idea to think beyond the norm. The corkboard project was a lesson in working with the Items tab, but it was also designed to trigger your thought process. While most of us head into a 3D modeling program to create cars, character heads or telephones, the project in Chapter 6 was a little less conventional, but a cool project just the same, and we'll put our own twist on it here.

In the previous chapter, you learned how to build objects and work with the Items tab. You learned how to rename an object in the Items tab and how to create materials. You also learned that if you press the Shift key and click on a primitive shape (such as a cube), you get a new mesh item called Cube. By pressing m and entering a name, you are assigning a material to these polygons. What modo is actually doing are two things: 

[Figure 1] The default Shader Tree tab is your home for all surfacing and render control.

  • Creating a polygon material selection set out of these polygons -- You can see them in the Info list under Polygon, Material.

  • Creating a new group layer in the Shader Tree that is linked to this selection set -- This linkage of a group layer and a set of polygons (or an item or item hierarchy) is called a mask. A mask makes sure that all the material and texture layers in that group are applied only to those linked polygons or item(s). If you choose a material from the drop-down menu that already exists, then you are just adding those polygons to the existing selection set and its associated mask.

Note: It's important to understand that a material is a selection set of polygons, and a mask is a group layer that references these polygons (or an item or hierarchy of items).

[Figure 2] Expanding the Render listing in the Shader Tree shows the default material and shader.

Keep in mind that the Items tab covered in Chapter 6 gets precedence when it comes to naming. If you name an item Material in the Items tab, it will result in a Material (1) name. That material then appears as Material (2) in the Shader Tree. With that said, try not to over think this process. Those numbers are one of the first things you'll see, and they can be confusing. But what's more important right now is selecting the right material and learning how to apply the right effects. If you explicitly name an item Apple and add a new group layer via the right-click drop-down menu in the Item List and rename it Apple, you will get Item=Apple (1) and group layer=Apple (2). But whichever one you create first gets precedence. So if you add a group layer named Apple and rename an item to Apple afterwards, the item is now Apple (2).

Introduction to the Shader Tree

You've worked with the Tools tab quite a bit up until this point, visible at the top left of the modo interface. If you look to the right, just next to the Items tab, you'll see another tab labeled Shader Tree.

When you click the Shader Tree tab, you're presented with a viewport that has four items, Render, Environment, Directional Light and Camera (see Figure 1). You'll also see a selection for Filter and Add Layer at the top. You'll come back to these later.

To the left of each of those three listings is a small triangle. Click the triangle next to the Render listing to expand it. You'll see four items -- Alpha Output, Final Color Output, Base Shader and Base Material, as shown in Figure 2.

Note: To introduce you to the Shader Tree, you'll work with a default modo interface with no geometry loaded. The best way to set this is to make sure modo is closed, then restart. Or if you have modo already running, from the File menu choose Reset to clear the viewports. Make sure you save any work first.

The base material in the Shader Tree is what drives everything above it. The material feeds information into the Shader, which then takes that information and feeds it into the renderer, taking with it color and alpha values. The alpha value is used for layering and keying in post-processing programs. The renderer then adds the appropriate settings you apply. While this might sound a bit confusing at first, don't worry. This chapter will break it down, and then you'll see first-hand how this clever little panel works.

[Figure 3] Here, Base Material is selected and its Render properties appear below (left). [Figure 4] By selecting the Render listing in the Shader Tree, you gain access to all of the render controls. 

Click the Base Material listing. You'll see a slew of controls appear beneath the Shader Tree in the Properties tab. By selecting a layer in the Shader Tree list, you activate the controls for that listing. Now even though there is no geometry in modo, you can still see the Base Material settings, such as Diffuse Color, Specular Amount and so on, as shown in Figure 3.

As you build objects and add surface materials, as you did with the project in Chapter 6, the material names you specify will appear here in the Shader Tree. But there's more to this area than meets the eye. This next project will show you how to work with a few settings in the Shader Tree. From there, you'll texture the objects you created in Chapter 6.

  • In the Shader Tree, click the Render listing. You'll see the Render properties appear beneath the Shader Tree, as shown in Figure 4. On the right side of the Properties tab, you'll see vertical tabs. The top selection is Frame, as shown in Figure 4. Here you can set the Resolution Unit value in Pixels or Inches. You can also change the size of your render, the default being a resolution of 640 x 480. The other settings apply to how modo renders, which you'll learn more about later in the book. For now, leave all of these settings at their defaults. The other vertical category listings include antialias settings, subdivision rates and displacement rates. You'll also see a category for Global Illumination, a powerful way to render your scenes with added realism. Take a look at these areas to familiarize yourself with their location, but leave the settings at their defaults for now.

[Figure 5] The Environment Material selection is where you control the color of the modo background for renders (left). [Figure 6] A quick render of a default modo scene shows the result of the Environment Material settings. 

  • Back up in the Shader Tree, select the Environment listing. When selected, you'll see a few options below in the Render properties, such as Visible to Camera, Visible to Reflection Rays and so on. These are all checked on by default.

  • When you expand the Environment listing, you'll see Environment Material. Select this and you'll gain access to the colors of the modo render environment from four-color gradients to physically based daylight. Figure 5 shows the selection.

  • In the Environment Material Properties tab, you can see that the Environment Type is set to 4 Color Gradient by default. Press F8 on your keyboard to render a preview frame. Figure 6 shows the result. Notice how the render shows the same color gradient structure as listed in the Environment Material.

[Figure 7] A two-color gradient removes the horizon line in the rendered scene (left). [Figure 8] A default light in modo also has a default material. 

  • Change the Environment Type to 2 Color Gradient, Nadir Color to pale orange, and Zenith Color to a deep blue. Do this by simply clicking on the color swatch to call up your systems color palette, or you can click and drag on the number RGB values. When done, press F8 again to render a preview of the scene, if your preview window is not still open. Figure 7 shows the result.

  • Click the triangle next to Directional Light in the Shader Tree listing. You'll see that the default is set to Light Material, as shown in Figure 8.

  • Now select the Directional Light listing itself in the Shader Tree. You'll see the properties change to some basic but important light settings. The settings here allow you to change the light intensity (Radiant Exitance), the shadow type, position and so on.

These are just a few steps familiarize you with the basic information in the Shader Tree. While you've not yet created anything, you can see how to access the various properties for Shader Tree items. Select the item, and the properties for that item appear below the Shader Tree in the Properties tab. Within the Properties tab, there can also be vertical tabs for additional tools. Remember this as you're setting variables for textures, camera render settings, and so on. Now move forward to see the Shader Tree in action by apply textures and image maps to the corkboard model you created in the previous chapter.

Each excerpt from Daniel Ablan's The Official Luxology modo Guide, Version 301 will help you discover the power of Luxology modo. The book covers the latest version of modo, which features new animation and sculpting capabilities as well as enhanced creative control for the user. Learn step-by-step how to use the modo interface and each tool and feature as you work within the application, from getting started to saving the final product. Skills are taught using projects that take the reader from simple modeling to complex tasks, taking advantage of various tools and options along the way.

The Official Luxololgy modo Guide, Version 301 by Daniel Ablan. Boston, MA: Cenage Course Technology, 2008. 456 pages with illustrations. ISBN 13: 978-1-59863-497-6; ISBN 10: 1-59863-497-6 ($49.99).

Dan Ablan's love of 3D animation sprang from a job as a corporate video producer. Along the way, he discovered 3D animation and within a year, formed his own part-time animation business. Ablan is now president of AGA Digital Studio Inc., a 3D animation and visual effects company in the Chicago area. AGA Digital has produced 3D visuals for broadcast, corporate and architectural clients since 1994, as well as post-production services. In between animation jobs, Ablan writes books on the subject. He is the author of eight best selling international books on 3D animation. He is also the founder of 3D, a website dedicated to 3D learning. He has written columns and articles for multiple magazines and has been teaching seminars since 1995 both across the country and at AGA Digital Studios. Ablan is also editor-in-chief of HDRI 3D Magazine, a magazine dedicated to animation and digital imaging.