Essential Blender- P17

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Essential Blender- P17

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  1. Figure MTD.18: The Map To tab. There are lots of options in the upper set of buttons, and these determine which properties of the material the texture will affect. Mousing over the buttons will bring up a tool tip that describes what each button does. The most commonly used ones are Col, Nor, Spec and Alpha, which we'll look at now. Col: Color. When this button is enabled, the texture works in conjunction with three other controls on this panel: the mixing dropdown (which shows Mix as a default), the Col slider just below it, and the color picker immediately to its left. As this is just the basics, leave the Mix dropdown alone (if you are familiar with mixing modes like Add, Multiply, Screen, etc. from other applications, you'll find all of your favorites there.) The Col slider sets the strength of the texture's affect on the base color of the material on a simple scale - 1 is 100% strength, 0 is 0%. The color picker sets the color that will be used for blending. Nor: Normal. Using textures to vary the normal of a material simulates bumps and detail across the surface. Use this button with the Nor slider to set how deeply the bumps appear. This is commonly referred to as "bump mapping".
  2. Spec: Specularity. A piece of metal that has dirt and corrosion on its surface will be rather shiny in clean places, but dull in the dirty spots. Using a texture to affect specularity allows you to simulate this effect. The Var slider determines how much of the texture is used for specularity, from 0 to 100%. It's important to note that properties like specularity (and emit, translucency, alpha, etc.) still use the settings from their main sliders in the Material Buttons as their baseline. This means that if you leave the Spec slider on the Shaders tab at 1, you most likely would not see any effect from the texture. Think of it this way: the Spec slider in the Shaders tab sets the lowest amount of specularity for the material, while the Var slider sets the maximum amount of specularity that will be created by the texture. So, the way to show the greatest range in values of specularity would be to set the Shaders tab Spec slider to 0, while setting the Map To tab Var slider to 1. Alpha: Opacity. The alpha setting works exactly the same way as the Specularity one. Just a reminder, though, to think of alpha as opacity, not transparency, so everything works intuitively. The greatest range of Alpha variation will be achieved by setting the Material tab "A" slider to 0 and the Texture tab Var slider to 1. Make sure to click ZTransp in the Links and Pipeline tab to get an accurate material preview and correct rendering with Alpha. Many of these buttons are not normal toggles, but three-stage toggles. For example, clicking the Nor button once turns it on, while clicking it again leaves it on and turns the label yellow. Clicking once more turns it off. That third state with the yellow label is a "reverse" setting. It uses the texture, but backwards. Under the Nor setting, what would have bumped out now bumps in, while what would have bumped in now bumps out. Likewise, the Neg (Negative) button can be used to invert a texture, and due to complex technical reasons this will not always produce the same result as the third toggle state of one of the property buttons. You are not constrained to using a single property on each channel of the texture stack. Careful selection and adjustment of the property buttons (say, Col, Nor, Spec and Alpha) along with their respective sliders (Col, Nor and Var) can produce complex effects within a single channel. So, with ten channels to work with in the texture stack, you can produce some incredibly complex materials. We've reviewed the four main components of Blender materials (base colors, shaders, reflection/transparency and textures), and explained the most common options relating to them. There is a wealth of additional features and options within Blender's material and texture system that we did not cover, but the basics presented here will give you a good starting point to begin exploring on your own. The Blender 2.3 guide and official online documentation contain explanations for every button and switch in the Blender interface and would be a good companion for users wishing to go beyond these basics.
  3. Chapter 9: Materials and Textures in Blender By Colin Litster Blender, like any 3D design suite, is essentially a simulation program. Points (vertices) are placed in a virtual 3D space and these points are joined to form faces. Faces are then lit with simulated lights, and a simulated camera is placed to look at your virtual object. All this has to be done before your simulated object and world can be rendered in all its glory. Blender's Material and Texturing system provides the tools that help you simulate a surface color or property that will turn a boring, gray plastic-looking object into something much more interesting. Figure MTT.1: A photorealistic render from Blender.
  4. This could be based on a photorealistic interpretation of a real material or on some artistic style, like a cartoon, or an impressionistic painting. Figure MTT.2: Line illustration render from Blender that simulates a hand drawn look. In other words, Materials and Textures offer an enormous palette of color, style, and effect that can be applied to untextured 3D objects, turning them into a truly inspiring picture or animation. Of course, this means that there is no magic button to press in Blender, or any 3D package, that will automatically produce realistic, or even good-looking, materials. You have to make decisions about many settings, as well as to apply observational and artistic skills. All of these choices can appear daunting to the beginning 3D artist. Indeed, many artists find it difficult to move from more traditional forms of art because of the apparent need to know every aspect of a 3D tool before attempting a still image or animation. Really, though, you only need to know the basics in order to get started. From there, you can build on that knowledge. In this section of the book, we will show you how to quickly simulate a realistic looking material, as well as provide a more general strategy to apply to any material situation. You will also see that you can start to achieve some very good results with only a few tools.
  5. The Material Interface For purposes of this tutorial, you are going to use the default Material Screen provided by Blender. Start the Blender application, then use either the keyboard shortcut Ctrl-Left/Right Arrow or the Screens dropdown menu to choose the provided Materials editing screen, which looks like this: Tip: Blender comes pre-configured with a Materials editing screen. Figure MTT.3: The default Materials editing screen. Approaches to Simulating a Real Material Time to get down to creating materials in Blender. For this exercise you will look at how a relatively complex surface material can be created with just a few commands and settings. Also, you'll see an approach to simulating a real material that you can use time and time again to speed
  6. up your production pipeline. Don't worry that some commands will be glossed over and given without explanation... we're doing a run-through to get you familiar with the basics. In most cases, we will come back to those areas in more detail later, and in the discussion section after the chapter. The best tools you can employ in creating any material are your eyes. Direct visual interpretation of what you are trying to simulate really is the best way to start material and texture creation. For that reason we will start with a surface to which all of us have fairly easy access. Figure MTT.4: A photograph of an office desk. You will start with the simple desk surface, ignoring for now the power adapter and cables. Creating the Object and Setting the Lights Any surface, such as your desktop, either scatters the light toward your eye (this kind of light is called Diffuse), or reflects it directly (called Specular). This means you require some simulated lights to represent the light sources that exist in the real scene. If you need to learn Blender's approach to lighting, you can refer to Chapter 11. Diffuse Light Any surface, such as your desktop, has small crevices, nicks and irregularities that prevent light from reflecting perfectly, as though it were a mirror. In fact, most natural surfaces have so much irregularity that they scatter any light that hits them, so the light that reaches your eye from any point on the surface may have come from almost any direction.
  7. Specular Light Some surfaces will also have specular highlights where the light reflects in a more concentrated manner, giving shininess to the surface. Figure MTT.5 The position of lighting certainly affects the way your eye perceives a scene, and for that reason it's important to set up the lights in your Blender scene to approximate the ones from the photograph. Without doing that, you can't get a good read on how to set up your Materials. In the example there are 3 lights. Light 1 represents the outside sunlight that is coming through the window. Lights 2 & 3 are there to represent light bouncing off of the walls and the artificial light source in the room.
  8. It is possible to set up very realistic lighting that will accurately mimic the properties of real lights, but it is often better to use quite simple setups that copy the general location and brightness of real world lights. Simple setups mean that you can easily arrange and fine-tune their effect and therefore concentrate on making a material perfect. Figure MTT.6: The desktop with the three lamps.
  9. Figure MTT.6.render: The provided scene, rendered with no materials. If you've worked through the modeling and lighting chapters, you should be able to easily make a nice approximation of this setup. For later in the tutorial, you will also need a simple model of the power supply and cables. If you are just working on materials and don't feel like modeling anything right now, you can find the file, called "materials_desktop.blend", with the models and lights preset in the "examples" folder on the included CD. An Approach to Materials Adding a New Material In order to begin, you need to create a new material for the plane surface. Select the plane that is your desktop with RMB. Under the Links and Pipeline tab in the Material buttons is the Add New button. Select this so that a new material will be created for your desktop object.
  10. Figure MTT.7: The Links and Pipeline tab, before clicking Add New.
  11. Figure MTT.7.clicked: The default Material. As you can see, Blender creates a default gray material for your object. It's from this default that you will make modifications to turn the material into more of a wooden, desktop-like surface. Don't worry about all those controls. At this stage only a few of them are necessary to produce your wooden desktop. Material Base Color One of the easiest things to do is to set up the base color of the material. Just below the preview tab you should see a Material tab with settings for the color. LMB inside the gray color area just to the left of the Col button, popping up the color picker.
  12. Figure MTT.8: Blender's color picker palette. Here you can drag across the color panels to select any color you like. Try it. LMB a color then confirm it by pressing the Enter key. The material will now have a diffuse color based on your choice. You are also able to manipulate the R, G, and B sliders directly in the material tab or to enter values with the keyboard to accurately obtain the color you require. That is what I want you to do now. LMB on the R value (Red) so that the number there becomes highlighted for direct numeric input. ! Enter 1.0 for R(ed) and press TAB to move down to the G(reen) entry. ! Enter 0.837 and press TAB to move down to B(lue) entry. ! Enter 0.438 and press the Enter key. I chose that color after very careful observation of the desk in the original photograph (obviously, the real desk is not black and white like the photo). When trying to determine the base color to
  13. use for a material, you must try to imagine what the real material would look like if illuminated evenly with a balanced white light. Tip: Diffuse and Specular colors are set on the Material tab. Even though you've defined the basic color of the material, you haven't told Blender anything about how this material reacts to light. Is it shiny, like wet rock, or does it have a soft, extremely diffuse appearance, like pool table felt? Blender implements both Diffuse and Specular shader models under the Shaders tab of the Material buttons. Figure MTT.9: The Shaders tab. The Lambert model is one of several available for Diffuse shading and the CookTorr is one of a series of Specular models. Later you will learn about the others but for now we are going to stick with the defaults. In fact, the default specular model settings of Spec 0.50 and Hard of 50 are fine for your desk surface.
  14. Tip: Diffuse and Specular shaders are chosen on the Shaders tab. Variation Across the Material Surface Almost no surface has a totally uniform color, shininess, or flatness. In fact, variation across a material surface is the single most important thing that will transform a dull and obviously computer-generated material into an authentic surface representation, or at least a more interesting one. Observation of the desk surface reveals that apart from the wood grain there are some subtle and random variations in color across the surface. You therefore need a similar random texture to give color variation to your shading model. In order to simulate these variations it's necessary to add textures to your material. Textures Blender offers the ability to apply up to 10 texture layers within a standard Blender material. Each texture layer offers a huge range of possibilities to help modify your material. For this reason, things can appear a little daunting when beginning to work with textures. We will be covering the details of textures in the discussion section. So for now, just follow along with the suggestions and see what happens. ! Switch the buttons view window to Textures (F6 or LMB the textures icon). ! LMB on the Add New button.
  15. Figure MTT.10: The Textures tab, before adding any textures.
  16. Figure MTT.10.clicked: The same tab after clicking "Add New". A new texture is created in the first slot with a default name. Currently there is no texture type assigned so the preview is blank. ! Click the Texture Type button, where it says None, to display a list of available textures, and from the list, select "Clouds". The Preview tab gives an indication of what the texture looks like. This one, as its name suggests, looks sort of cloud-like.
  17. Figure MTT.11: The Texture tab and Preview tabs with a preview of the Cloud texture type. ! Change the Noise Size to 0.158 and the Noise Depth to 3. ! Switch back to Material buttons (F5 or LMB the materials icon). Tip: Textures provide variation to a material. As soon as a material has a texture attached, a lot of new options appear. We will be dealing with most of these later, but for now you only need to worry about three things: ! How will the texture be projected ("mapped" is the proper CG term) onto the surface? ! What will be the size and orientation of that projection? ! And how will the texture interact with the underlying material? Mapping
  18. The default mapping is called "Flat", and fortunately, you have a nice flat surface to which we would like you to apply the texture. Obviously, there are other ways to map textures onto models, several of which will be covered in the discussion section. One, UV, is so useful, it has its own chapter (Chapter 10). The tab that has these settings is called Map Input. If you don't see this tab in your Material buttons window, either MMB-drag the window or use the scroll wheel inside of it to show the additional tabs at the bottom of the view. Figure MTT.12 Ensure that the Flat and X, Y and Z buttons are turned on as in the illustration. These are the defaults for new textures though, so you shouldn't have to change them. Size and Orientation Although you have already set a Noise Size in the Texture buttons you are able to have greater control over the texture's size and orientation in the Map Input tab. Alter the sizeY to 10.00. This will squash the Y axis mapping of the texture (front to back) which makes it look more like a variation caused by the direction of the wood grain.
  19. If you were to render now the material would look very strange (try F12 and see!) Currently Blender doesn't know what you want the texture to do, so it's applying it as a default Magenta color. Texture Interaction with the Material (Map To) The Map To tab in the Material buttons also has a host of options that we will cover later. For now, it's a color variation that you're interested in, so the Col (Color) button and the Mix color are the important options. Set the Map To tab to match the highlighted portions of the illustration. Figure MTT.13: The Map To panel. If you render this time you will see that the desk material looks much better (F12). Bumps It's very common for a surface to have bumps, either due to its natural makeup or as the result of damage and erosion. Adding these details can raise a material's believability. As you're shooting for believability, not an exact copy of reality, such details don't have to be exact photographic duplicates of what you can see. For instance the wood grain on the desktop would be very
  20. difficult to copy exactly. However, it should be possible to come up with similar patterns and colors so that it looks like the simulated desk was produced from the same materials as the original. Let's have a go at creating the wood grain. If you look closely at a real wood surface like that of the desk, you will see that it has both depth and color. In this case, it appears that a covering of varnish or stain has been added, which pooled slightly in the grain dents, causing them to darken a bit. In fact, the grain is quite pronounced and much darker than the wood surface. Once again, careful observation is the key. It is often not good enough to work from what you imagine as "wood" - unless you are a practiced artistic observer, your memory will have already done a good bit of shorthand and simplification to it. Find a real piece of wood (or a detailed picture) and study it. Don't worry. You won't have to do this for every material for the rest of your life. Once you get the hang of artistic observation and visualization, you'll often be able to do "good enough" materials just by detailed visualization. Textures Are Your Friends Since you have 10 Texture slots available within any single material, you have plenty of space to add wood grain to your material. It's possible to add a new texture right from within the Material buttons. ! Find the Texture panel in the Material buttons. ! LMB on the empty texture slot below the one you have already created. ! LMB on the Add New button to create a new texture in that slot.
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