Electric Image Animation System 7 Tutorials
Shaders / Reactive Shaders
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Subtitles of the Movie (Electric Image Animation System 7 / Shaders / Reactive Shaders)
There is a special class of shader called a Reactive Shader. Reactive shaders react to a channel from another source to drive their effect. Usually this is a color value. Let's take a look at this cube. This is the cube's actual polygonal color. This cube was painted in another program and brought into Electric Image. In its Material Window, you can see that I have a Noise Factor Shader applied. Let's open it up. We have some extreme mountain-like noise here. In the special area of the shader, Use Grayscale Reactive is turned On. Let's click OK and render a snapshot. The noise only appears where the white exists on those painted polygons. The noise reacts to the gray luminance value on the model. Just know, you need to have Use Polygon Color checked on in the diffuse channel of the material and also in the Models Info Window, make sure Color Blend is check on in the Shading Tab or the shader won't see the model's painted polygons. There are other methods for reactive shaders to be driven by an external force. In most cases you can drive the shader's effect by a texture map. Let's look at another model in the project. This sphere has two image textures; the billiard texture and one of the grid textures, as well as a reactive version of bumpy noise. Any time you see a shader name that's followed by an R, that shader will have reactive controls. I'm going to turn off and on the textures one more time; the blue billiard texture, the red and cyan grid and then on top is the shader called Bumpy Noise R. A stacking order is important here again. Let's open up the Shader's Controls. Notice that it has two reactive pop-ups; one for bumps and the other for opacity. If I set both of these to red, then the shader should be driven by the color red. Let's render a snapshot. There. We see that the shader only appears where the red grid is on the texture directly beneath it. Let's change the shader controls again and set both reactive fields to blue and re-render. Now the shader appears where the cyan color was, but why not the entire sphere? Cyan is equal parts blue and green, so why not cover the whole thing? Because the calculation on the materials starts from the bottom and works its way up. So the result is that the blue billiard texture is completely covered by the cyan and red grid. The shader doesn't know it's there. Let's turn off the grid and see what we get. That's more like it. Now we see full coverage except for the black number. Black has no color in it but the white has equal amounts of red, green and blue so the shader works in both the white area and the blue area of the billiard texture map. Another example; this model has painted polygons as well. It also has the Bumpy Noise R Shader applied. But how? Let's look at the shader's controls. This time the color opacity is limited to the saturated areas it sees and the bumpiness is limited to the brightness values. Let's go ahead and render. The white color of the model's polygons has no saturation so the color of the shader only appears where the green and red were on the painted polygons. However, everything is pretty bright on the model; bright red, bright green, bright white. So everything gets bumps. Let's look at one more example. This cube has two shaders; the Bumpy Noise R on top of the Eroded Shader. Let's look at the Eroded Shader for a moment. The surface color is red and the whole color is black. Note that I've unchecked Erode Holes. Let's close that. Now look at the Bumpy Noise R Shader and see that its Reactive Controls are both set to No Red. Let's make a snapshot. Cool. The bumpy noise only appears where there is no red. Now it looks like the model has been scraped away to reveal a sandy interior. Reactive shaders are extremely powerful and will help provide realism to your materials. Once you start playing with them, you'll find yourself creating all sorts of useful and fun combinations.
Tutorial Information
| Course: | Electric Image Animation System 7 |
| Author: | Scott Simmons |
| SKU: | 33996 |
| ISBN: | 1-935320-45-9 |
| Release Date: | 2009-06-01 |
| Duration: | 8 hrs / 102 lessons |
| Work Files: |
Yes |
| Captions: | No |
| Compatibility: |
Vista/XP/2000, OS X, Linux QuickTime 7, Flash 8 |
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