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'The Official Luxology modo 301 Guide': Masking Effects

In this fourth 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.

The term mask will be used a lot when it comes to modo and the Shader Tree. This section will use one image to mask out another. It's a great way to shape a mesh without actually modeling it.

  • 1. Continuing from the previous exercise and your corkboard object, select the newspaper mesh on the board. You can choose Items mode at the top of the modo interface, and then click in the viewport to select the mesh.

Note: A quick way to jump to Items mode is to press the Shift and spacebar keys at the same time.

  • 2. Click over to the Images tabbed viewport to the right of the Items tab.

3. Select Load Image and, from the book's DVD in the Chapter 7 folder, within the Projects directory, choose the Newspaper.png image.

4. When the image loads, drag and drop it onto the newspaper mesh. Figure 1 shows the setup.

[Figure 1] Applying a newspaper clipping to the mesh is easy by loading it in the Images tab, then dragging and dropping it onto the mesh.

  • 5. Expand the Render group in the Shader Tree, if it's not already.

6. Expand the Newspaper [TE: mask] group, and then select the image layer that was added by dragging and dropping the newspaper clipping image onto the mesh.

7. In the Properties panel, click on the Texture Locator vertical tab.

8. Change Projection Type from UV Map to Planar.

9. Set Projection Axis to Z.

10. Click the Auto Size button. The newspaper clipping is now mapped, but not aligned. Click and drag the Position Y arrows to bring the image up manually on the polygon. You can also just type in roughly 200mm, as shown in Figure 2.

[Figure 2] Adjusting the newspaper clipping settings in the Texture Locator vertical category of the Properties panel maps it on the mesh.

  • 11. Now you know as well as anyone that newspaper clippings hanging on a corkboard need a ripped edge, right? No one cuts out clippings perfectly. You can see that the image already has rough edges, but the polygons are still showing through. In the Images tab, load the NewspaperMask.png image. This is a 32-bit image with a Photoshop painted rough edge.

12. When the image is loaded, click over to the Shader Tree.

13. Now right-click on the existing image map for the newspaper and duplicate it. Then select the new image within the Newspaper group in the Shader Tree.

14. From the Properties tab, select the Texture Layer vertical tab. Change the image to the Newspaper Mask image. What you've done is duplicated the image map settings you previously applied, merely changing the actual image used. Figure 3 shows the properties. Figure 4 shows the applied image.

15. You're going to make a few more changes, and then you'll see how this all comes together. Select the Newspaper Mask image in the Shader Tree within the Newspaper layer group. Notice that its effect is set to Diffuse Color. This is fine for the actual newspaper clipping image, but the paper mask image is going to be used to cut away the mesh.

[Figure 3] By copying an applied image, you can simply change the image used but keep the existing settings (left). [Figure 4] Duplicating images is an easy way to create texture masks. 

  • 16. Change the effect, right-click on Diffuse Color and select Transparent Amount.

17. Once the Effect value is set to Transparent Amount, you might not see the correct result. Why? The paper mask image is white on a black background. To effectively clip the mesh and utilize the transparency, open the Texture Layer category in the Properties tab and click Invert.

18. Making sure you have a preview window open, you can see the instant result. Use the Render tab to quickly call up a preview. Figure 5 shows the setup.

Note: Remember that the white value of an image or procedural texture will equal a value of 100% for that channel, while a black value equals 0%. In this case, you’ll want to invert the transparency map so the white values are around the edges of the newspaper clipping, making them transparent.

[Figure 5] Changing the effect of the paper mask to Transparent Amount and inverting the image allows you to clip away part of the mesh.

  • 19. Save your work! Now all you need to do is move the thumbtacks into place since you've clipped away parts of the newspaper.

Take a look at Figure 6. This is how the Newspaper layer group currently looks. Let's break this down so you see what's happening.

The Material layer within the Newspaper mask sets constant values for all of the Material layer’s attribute channels (Diffuse Color, Specularity, Transparency and so on). You can alter these constants by adding texture layers above the Material layer. A texture layer can be an image, a procedural texture or a gradient. These textures can be set to affect any channel (Diffuse Amount, Reflectivity, Transparency Color and so forth) via the Effect column. In this case, you have added image map texture layers to affect the Diffuse Color and Transparency channels. The values stored in the image maps (the pixel colors) define the values for the channels they are assigned to. So instead of the constant color in the Material layer’s Diffuse Color channel, you get all of the colors in the Newspaper image map. And instead of the Material layer’s Transparency channel value of 0%, you get the Transparency values defined by the black-and-white pixels of the Newspaper Mask image. These texture layers will override the Material layer channel below them, but they can be mixed with the Material layer values (and with other texture layers) by varying the Texture layer’s opacity setting and Blend mode.

[Figure 6] The Shader Tree, although simple in appearance, is quite powerful. Here, the newspaper mesh is turned into a clipping on a corkboard with a few texture layers. 

Your Next Few Steps

By no means are you done using the Shader Tree. Actually, you're just getting started! But as you can see with these few simple actions, your corkboard model is already taking shape and looking good. You've added a procedural computer-generated texture layer. You've mapped images and applied different effects. So what more could you do? On your own, go ahead and map the other items on the corkboard. Try experimenting with different types of images, remembering that if you create something in Photoshop or another paint package, to do so on a transparent background. There's an additional photo in the Chapter 7 folder, within the Projects folder on the book’s DVD. You can use this image, as well as any another Post-it Note. Try making some of your own as well. Save that image as a PNG to retain the 32-bit alpha data that modo will read. Perhaps you can tear off a small piece of the second Post-it Note, using the same effect that you did with the newspaper? Maybe you have a corkboard in your office or home. Take a photo of it, and apply that image to the board rather than using a computer-generated texture.

In Chapter 8, you'll dive even deeper into the Shader Tree. There's much more to this than meets the eye, but you'll soon find that out. Later in the book, as you get into more advanced modeling, you'll also learn how to use modo's powerful painting and sculpting features to create your own unique textures, and then animate them.

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 Garage.com, 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.

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