Limiting materials with selection tags
Video: Limiting materials with selection tagsIn the previous movie we applied this star to the wing of our MiG fighter here, but I only want the star to show up on top of the wing. I'd like to have a different material on the underside. So, in order to limit that material to just showing up on the top of the wing, I have to use a technique called a Selection tag. The way the selection tag works is that you first need to select some polygons. Then, once you've selected those polygons, you can identify them using a special tag that then gets used in the material tag to limit where the selection shows up.
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CINEMA 4D Essentials with Rob Garrott is a graduated introduction to this complex 3D modeling, rendering, and animation program, which breaks down into installments that can be completed within 2 hours. This course shows how to lend 3D objects color, transparency, and life with materials, textures, and lights. Author Rob Garrott explains how to create a variety of surface textures, from smooth and reflective to bumpy and flat, and how to add dramatic depth and shadows to your scenes with the different light types in CINEMA 4D. The final chapter discusses texturing in 3D with the BodyPaint module, which can also help hide UV seams.
- Understanding material channels
- Applying materials via projection
- Limiting materials with selection tags
- Texturing type
- Using Falloff to limit the effects of lights
- Working with visible or volumetric light
- Painting on objects and textures with brushes in BodyPaint
- Hiding seams with projection painting
Limiting materials with selection tags
In the previous movie we applied this star to the wing of our MiG fighter here, but I only want the star to show up on top of the wing. I'd like to have a different material on the underside. So, in order to limit that material to just showing up on the top of the wing, I have to use a technique called a Selection tag. The way the selection tag works is that you first need to select some polygons. Then, once you've selected those polygons, you can identify them using a special tag that then gets used in the material tag to limit where the selection shows up.
To begin our selection process, we have to go into Polygon mode, so I'm going to select Polygon mode here over in the left and then click on my cube. We're looking at the underside of the plane right now, and this is where we don't want it to show up, so we're going to select the polygons that are associated with the top side of the wings. Let's go over to the top of the wing. Now I've got a feature turned on called Isoline Editing, and Isoline Editing is causing the polygons to be deformed in the shape of the HyperNURB object. That makes it very confusing to see where the polygons actually are, so I'm going to go to the Options menu and uncheck Isoline Editing right here.
Now I can see just my plane shape, and this is the low-poly plane that's underneath the HyperNURB that's getting smoothed. I can also turn off my HyperNURB so I can just see the polygons that make up the wing. So what I'm going to do is use the Selection tool and grab just these polygons for the wing and I'm going to name them. Actually, I'll grab all these polygons that make up the top of the wing, and I'm going to call those polygons Top left wing. Anytime you name something right or left, it should always be from the object's point of view. When you're sitting in the plane as a pilot, this would be the left wing.
To get the Selection tag, now that I've got the polygons selected, I go to the Select menu, and right near the bottom is Set Selection. When I let go of that, I get this red triangle on the cube object, and this is the Selection tag. This stores that information right there. I can deselect those polygons. I'll click anyplace and deselect them. I can always restore the selection by clicking on it right there. I can name that selection. We'll call it Left wing top. Now I want to do the same thing for the right wing.
But before I do that, I have to be very careful. If do another Set Selection while I have that tag selected right there, it will overwrite the contents of that tag. I don't want to do that. So let's deselect that tag, click on the cube again, and then select the polygons that are on the right-hand side of the plane. So let's go to those polygons right there, and we've just got those polygons selected on the top of the wing on the right-hand side. Now I'll go back to the Selection menu and do a Set Selection, and then I can call that selection Right wing top.
Now, the way we use these is we have to identify which tag is which for the textures. Which one of these star textures is the one that's on the left and which is the one that's on the right? To do that, I can switch to the Texture tool and then click on a tag. So this is the one that's on the left-hand side, so it's going to get the left selection tag. So I go to my tags and this is the left selection. That's my left star. Sometimes people will take these and order them so they're right next to it. So there is my left tag for the texture. There is my left selection right next to it.
Now I can take this texture and in the Selection field that's on the Tag properties, I can drag that triangle right down, and there it is. When I let go of that and orbit around, you can see that the star is gone from the underside. Let's watch this as we do the same thing on the other texture. Click on that Star texture there, drag the triangle in, and there it goes. The star is now limited to just the top of the wing. When we orbit around, we could see that our stars still show up in the top, but they don't show up underneath. This technique is incredibly valuable and it can be used in all kinds of situations: putting labels on bottles or cans, in this case putting decals on models of objects, but it's a really valuable technique and one that you've got to keep in your toolbox.
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