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3. Set falloff. To put the brindle skin in a specific spot on the cow, we'll use falloff. Make sure you've got the brindle SimbiontLWShader open.
Render this out. Only the bottom part of the cow shows a faded brindle. Time for some adjustments. 4. Adjust falloff. There are two problems. The first is that the blending is a bit broad. Also, the falloff is happening from the object's origin, which is down at the hoof level. Raise this up.
Render this out. The brindle patch is smaller, but the edges of the blended areas are still pretty fuzzy. Time to use a feature of SimbiontLW to fix this.
Render it out. As you can see, it's a much sharper transition from one shader to the other.
The biggest drawback to using falloff to layer shaders is getting the position and shape just right. Using NULL objects to position the center of the texture can help, but if you want more control, you need to use something more advanced. If you're going to take a break, save your work since we'll use it in the next section. |
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1. Remove falloff. If you are starting with the cow from the Falloff section, remove the falloff.
Now the brindle surface should cover the cow completely. 2. Assign a procedural texture to control blend. We're going to control the way we composite the brindle skin with a procedural texture.
Try a test render. All brindle - what's going on? A quirk with textures. The value of the blend parameter in SimbiontLWShader is 100% and the Texture Value of the Turbulence texture is 100%. So nothing is happening. Change either of these values to 0% to get it working. Changing the Blend value is better, if you change the Texture Value to 0% you'll get a completely black preview in the Texture Editor. If you've got it set up properly, you should see patchy brindle spots on the holstein cow. 5. Set Blend in SimbiontLWShader to 0%.
Kinda neat, but Incidence Angle isn't that useful for general shader placement. Go back into the Texture Editor for the Incidence gradient and select the Input Parameter. Take a look at the last item in the list: Weight Map. You can create any weight map you want and use it to blend between shaders. This is a very powerful tool for mixing shaders. You can assign keys to your gradient to control the sharpness and bias of the mixing just like we did with the Incidence Angle, but it will be using your hand-painted weight map as the basis. If you're not familiar with weight maps, take a look at our weight map tutorial. It goes through the steps of creating a weight map for an object. The weight map is used to control a tweak in that tutorial, but you can use a weight map to blend between two shaders as well. To the right is an example of the cow with the same two shaders controlled by a weight map. |
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1. Surface the cow with a base layer DarkTree. We're going to abuse the cow one last time. Set up the scene the same as before (nice side shot of the cow).
2. Layer a second DarkTree on the cow.
If you have the Alpha Clips option on, the empty areas between the lichen will clip the entire surface away. While this is great for chain link fences and gratings, it's not that useful for lichen. Go ahead and render out the result. You should see a brick surface covered in lichen.
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Copyright © 2006 Darkling Simulations, LLC. All rights reserved. Any questions? Mail me! skyler@darksim.com |