Shading

Procedural orange skin

There’s a vast variety of oranges and citrus fruits, each with their distinguished color, shape and texture. But they can all be created using the same basic set of nodes.Open the scene orange.scn, select the Orange and press [7] to open a Render Tree. From the Nodes > Texture menu get a Cell Scalar node and open its PPG. Many of the changes made to the nodes are subtle and may be hard to see solely relying on the shaderball. To get a better view of how the values affect the output you can temporary connect the current node directly to the Surface input of material node and draw a render region in the viewport.

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Using individual textures in shared materials

The reason you apply the same material on multiple objects in the first place is usually because you want them to be exactly the same. That’s pretty much the definition of sharing the very same material. With that being said, let’s discuss how you can setup a shared material but still being able to control parts of it on a per object basis. While this answer confines to using an individual texture, there’s nothing stopping you from adding additional individuality. But then again, if you really want completely different appearance for each and every object you’re probably better of using separate materials in the first place. 

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Changing color of an objects based on its distance to another object

There are many instances where you want to be able to control an attribute of a shader based on its distance to the camera or another object in the scene. Regardless of the end effect you’re trying to achieve, the procedure of getting there is about the same.

Select any of the spheres (they all share the same material) and press [7] to open a Render Tree. From the Nodes > Conversions menu, get a Scalar to Vector node. This node enables you to enter any XYZ coordinates and by linking their separate values to the corresponding value of the Ctrl_Null, you’ve efficiently extracted the nulls position and made it available in the render tree. Open its PPG and click the Lock icon to pin it to the screen. Select the Ctrl_Null and press [Ctrl] + [K] to open its transform PPG. Drag the animation icon (the green divot) for the X Position (in the transform PPG) and drop it onto the animation icon of the Input X in the Scalar to Vector PPG. Repeat for the Y and Z position.

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Creating procedural X-ray shader in XSI

Röntgen ray, or X-ray as it’s commonly known as, is a form of electromagnetic radiation. Its short wavelengths are capable of penetrating the soft tissue as well as the bones in the human body, which has made it very useable in the modern medical services. Nevertheless, the number one use of X-ray is probably in science fiction TV shows and 3d animation.

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Adding Ambient Occlusing as a lens effect

Adding AO globally
While you commonly would setup and render the ambient occlusion in a separate pass, it doesn’t mean it can’t be done in a single pass as well. By adding the AO to the camera rather than the individual materials, you can control the effect globally and you don’t have to change a single material. Open the scene cube.scn from this issues DVD. Press [8] to open an Explorer, select the Camera and press [7] to open a Render Tree.

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Animating frost growing across the surface

This is a very common question. Okay perhaps not the frosted effect, but the part about changing the textures or materials for an object over time. You obviously need a surface for the material so start a new scene and create a simple object. Or just open the scene frost.scn from this issues DVD. Select the frost object and from the Get > Material menu choose Phong and Press [7] to open a Render Tree. Get a Gradient node from the Nodes > Texture menu and a Mix 2 Colors node from the Nodes > Mixers menu. Connect the gradient node to the Weight input of the Mix_2colors node and the Mix_2colors node to the surface input of the Material node. Double click on the gradient node to open the PPG and switch to the Texture tab. Click the New button and from the menu choose Planar XY.

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Coloring hair using procedural textures

Creating the procedural
Select the pelt object and press [7] to open a Render Tree. Get a Fractal node (from the Nodes > Texture) and a Color Matte node (from the Nodes > Color Channels). Connect the Fractal node to the Input of the Color Matte node and the Color Matte node to the Ambient and Diffuse input of the Blinn node. Open the Fractal PPG. In the Texture tab, click the New button and choose Planar XZ. Switch to the Advanced tab and set the UV Remap Maximum to 5 for all three axis.

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Create procedural leather material in XSI

Color variation
Start by installing the BA Shader Collection Essential add-on from http://www.binaryalchemy.de/index_dev.htm. Open the scene leather.scn from this issues CD. Press [8] to open an Explorer and select the group Leather_material. From the Get > Material menu choose Blinn and press [7] to open a Render Tree. From the Nodes > Textures menu choose More… In the Browser, click the Paths button and choose the Binary Alchemy Shader Collection – Essential. Select the BA_fractal4d and press OK.

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Cartoon Explosion

Even though it’s just about impossible to find a Hollywood blockbuster these days that doesn’t include its fair share of special effects and explosions, people just don’t seem to ever grow tired of them. On the contrary; take a poorly written excuse for a story, add a couple of nice, rich explosions and some other FX while you’re at it, and people will still see it. Let’s not single out a specific film because there’s just too many to choose from. Nevertheless, in all fairness sake, the sheer fun of blowing things up just might vindicate an otherwise totally uncalled-for explosion, or possibly even a bunch of them.

Without getting to scientific, let’s have a quick look at what we are about to create. Everything explodes differently, so depending on what’s causing it the result can range from a massive eruption of fireballs to a modest puff. Even so, they do share the same elemental course of events. The abrupt and violent release of energy sets of the explosion from a small or limited area and will aggressively grow larger. As the explosion or cloud travels away from the point of origin it loses its energy and will settle down and gradually fade away.

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Color at Vertices (CAV)

The short answer to the question is No. Well, if we are to be perfectly honest the elongated answer is sadly no as well. At least not in any sense that can be even remotely considered a 3d painting feature. With that being said, you do have some basic options to paint or store (color) information directly on your geometry. While they are limited at best, yet they just might do the trick if you’re not in the need of anything too fancy.

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