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- Understanding shading concepts
- Simulating the Fresnel effect for realistic reflections
- Rendering transparent and translucent surfaces
- Comparing mental ray and Maya standard shaders
- Introducing the mia_material
- Developing shader networks
- Using subsurface scattering shaders
- Mapping polygon UV coordinates
- Incorporating texture nodes into networks
- Improving skin detail with ambient occlusion
- Painting bump maps
- Creating normal and displacement maps
- Troubleshooting maps
Skill Level Intermediate
In this movie, I am going to give you a brief overview of how to work with texture nodes. Texture nodes add additional detail to your shader networks, so that you can extend the capabilities of your shaders and start to make them look more realistic or add special effects or so on. So how do you connect a texture node to a mental ray shader? Well let's take a look here. I'm going to apply a mia_ shader to the sphere. So I am going go to the Window > Rendering Editors > Hypershade, and under mental ray Materials, I'll click on the mia_material-X node to create the node, and I am going to select the sphere, right-click over the material in the Hypershade and choose Assign Material to Selection, to know it's assigned.
So, I'll select the sphere, and in the Attribute Editor, click on the Material node, this is the mia_materialx2 node, and as you know we have various channels within the shader that control its attributes, for instance the Color channel, controls the diffuse color of the shader, so I can move the slider back and forth to make it lighter or darker. I can click on the color swatch and change the color using the color chooser. What if I want to have a little more detail to the color? Well, that's where texture nodes come in.
And to create a texture node, you just need to go to the little checker icon to the right of the slider, and I will click on this and this opens the Create Render Node window, and you can see under Maya, we have 2D Textures, 3D Textures, Environment Textures, and Other Textures, and under mental ray, we have mental ray specific textures. So these are all the textures that you can use with mental ray. You can of course use any of the Maya Textures in your mental ray shading networks. There is no problem with that.
They should work just fine. The mental ray textures are specific to mental ray and so they only work when rendering with mental ray. So for example, if I click on the Checker texture in the Create Render Node window, you can see it automatically connects the texture to the shader, which is then applied to the sphere here. So you can see how the checkerboard looks. If I go into the Hypershade and right- click over the Material and choose Graph Network, you can see that I have the shader, the mia_material_ x2 shader, the checkerboard and the place to 2D Texture node, which determines how the texture is applied to the sphere.
And if you notice, there are arrows in between here and if I hold the mouse over the arrow, you can see how the connection is made. So the out color of the checker is connected to the mia material diffuse channel and the outchecker alpha by default is also connected to the mia material to diffuseA channel. The specific connections may change depending on the material that we are using. If I want to break the connection between a checker texture and the shader, I can select the Arrows and Hypershade and just press the Delete key.
Another way to do is to right-click over the Color channel in the material and choose Break Connection and that breaks a connection between the texture and the shader. If I want to delete the texture altogether and select it in the Hypershade and press Delete key and that removes the texture. Another thing I like to do is I'm working in a Maya scene and experimenting with my shaders, you fill find that these nodes start to stack up after while and everything get fairly cluttered. So to neaten things up sometimes what I'll do is I will choose Edit > Delete Unused Nodes, and this deletes all the nodes that aren't currently connected to shader network and that can make the scene a little bit neater.
I have a shader network already connected with some textures that I'd like to show you, so I am going to select the sphere and choose Control+H to hide it, and I have a group called Leaves here. So I am going to select the group in the outliner and choose Display > Show Selection, and the leaves are just two flat plants. That's all they are and you can see that I've used some File Texture node, to create the color of the leafs. And If do a render here, you can see what they look like. So when I do a render, you see that I have the leaves and the edges here and even have a little translucency going, so we can see the shadow cast from this leaf onto this leaf is visible through the leaves, so that's a little bit of translucency there.
And I'll show you very quickly how I created that effect, so I select one of the leaves and click on the leafShader tab in the Attribute Editor and in the Diffuse section, under the Color channel, if I click on the arrow to the right, this will show you that I have a very basic leaf color texture applied and this is just a photograph of a leaf connected to this channel. Let's take a look real quick in the Hypershade. I am going to open Window > Rendering Editors Hypershade, and right-click over the Leaf shader material and choose Graph network and I have three file textures applied here.
So if I hover over the arrows here, you can see that the outcolor of the leaf photograph is connected to the Diffuse channel and I also have a second copy of the file and it is connected to the Refreshing Trans Colors. So let's take a look. What does that mean? If this label is not descriptive enough, it's a good idea to look in the Attribute Editor to get a better idea of what's going on. What this actually means is this is the translucency color. So the mia_ material has a Translucency channel which is allowing me to see that shadow.
I am going to open up the Render View. The Translucency channel is creating this effect, so that I can see the shadow of this leaf through this other leaf. And I have just connected a second copy of the File Texture to the Translucency channel. As a side note, I just wanted to let you know that in order to get the Translucency channel to work in the mia_ material, you have to have at least some amount of transparency. So transparency needs to be at a value that's above zero.
So I have it up that .759 and I just chose this value through experimentation and then you can turn on Use Translucency and if you just want a regular color, you can just choose a color, but in this case I have actually used a File Texture. The only problem with using translucency is now I have occupied my Transparency channel with this translucency color but I also want a cutout so that I don't see the black parts of the plane. I only see the cutout shape of the leaf. To do this, I have connected another texture down here to this Cutout Opacity channel.
That's found in the Advanced section of the material. This is kind of like a little secondary level oftransparency. So this allows me to add an additional Transparency channel to this network and this is something that you only find in the mia_material network and this is one of the reasons why I like this shader so much is because it gives you more options for creating transparency. So if look at the Hypershade, what I have is just a very simple black and white texture that's been applied to the Cutout Opacity. And if I hover my mouse over the connection between this File Texture and material, you'll see that is the alpha channel of the image that's been connected to the Leaf shader network's Cutout Opacity.
This image actually does not have an alpha channel. It is just a simple black and white image called leafCutout.tif, so there's no alpha channel. So to get around that within the File Texture node, there is a option called Alpha Is Luminance. So this is taken the luminance value, in other words the bright values of this image, and using that as the alpha, so if this is clicked off and I do a render, you'll see that I'm losing my cutout ability. I am just getting all the black part, which is not something I want. When using a File Texture in the Cutout Opacity, you want to make sure that Alpha Is Luminance is turned on.
So that's some of the basics of using texture nodes within a shader network, they can certainly add a lot of detail to your shaders making your objects look more realistic and even a simple plane could be turned into a leaf.