Fading the Edges of Hair that is Applied to Polygon Selections

Photo of Darrin Frankovitz

Instructor Darrin Frankovitz

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Fade the edges of hair on polygon selections.

In this quicktip you will learn how to position a 2D Gradient with the fit to region command to control the density of your hair object. Then, by using the projector shader I force a hair material to adopt the settings from a regular texture tag so that the hair material channel has the same position, projection, rotation, and size as the texture tag!



- [Instructor] In this quick tip, we'll use the projector shader to fade the edges of this grass that's applied to a polygon selection. And in this render, we can really clearly see those edges. So we want to hide this. So let's check out the file. So here's the ground, and here are the selected polys, and our hair object. Now that's already applied. Everything's already here, so how are we doing this? Well, we're actually going to take advantage of the density setting. And we're going to use a circular...2D circular gradient. But we sort of already see how this is going to work on the land. So let's go ahead and apply that gradient to the object. And we're going to go ahead and turn on textures in our view port. Okay, so now we can see that gradient is way off. So to get it into position, I'm going to right-click on that tag. And you know what? Let's move this over here. I'm going to right-click on that and then select fit to region. Now, my hair is selected, so I have the bounding box. I'm going to use that as a guide in my view. Click and drag a rectangle. And in that area, the texture will be fit. So it's projection is set to flat and the coordinates position, scale and rotation, are all automatically set. So now that that's done, I need to get this into the hair material. The problem is that the hair material tag doesn't have that projection or that coordinates tab. So the solution then is to go into... Here's the gradient here. I'm just going to copy that. As we go into the hair material, to the density, and I'm going to paste that exact same gradient, but we still don't have those settings. So I have to use a really special effect shader and that is... Oh, we can't even see it. Let's see if I can fix this. Effects. Projector. The projector shader. I added that. It automatically places the gradient into the projector shader, and all the settings of this are the same as we have in a texture tag. All this shader does is allows us to assign a unique texture projection in a material channel. So, how do we get the settings from this texture tag into here? Well, it's really easy. All I have to do is single-click on that tag, so it's the active texture tag, and then click on paste tag. And it automatically transfers all the settings. Now, let's just turn that on, and let's hide this gradient, and we'll go into our view here. And I want to do a little render right here. So this is a standard renderer. You know what? I'm even going to...no, I'll leave it on. Okay, so there we go. Now we can see that it's fading, according to that circular gradient, and let's zoom out and get a bigger picture here. There we go. All right, great. Well, thank you very much for watching this quick tip. I'd especially like to thank crew Non-stop, who asked how to do this in a Cineversity one-on-one session. And very graciously provided this scene for me to illustrate this for all of you. Thanks everyone. Bye. - [Announcer] If you're interested in personalized training or project assistance, visit cineversityoneonone.com and visit cineversity.com for more great tutorials and resources.
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