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When you are texturing a model, creating a guide to the major parts of the body for the UV layout can be very helpful. A guide can spare you a lot of grief if you have trouble recognizing the various parts of the model within the jumble of lines that make up UV layouts. The 3D Paint Tool can help you accomplish this, but it can be a little confusing if you are not familiar with it.
First of all, the model has to be UV mapped, and it needs to have a material applied (without a color map) for the 3D Paint Tool to work properly. When these two criteria are met, you can get started.
To avoid confusion, hide everything except the objects to which your current material is applied. Start with the sword, so you can hide the body and the head.
Vertex coloring is one method that some game engines use to add large swaths of color to a model without having to edit the texture files. Many game engines project lighting onto models using vertex coloring as well. To apply per-vertex coloring in Maya, select the geometry, and navigate to Edit Polygons > Colors > Paint Vertex Color Tool > Options. This tool works very similarly to the 3D Paint Tool, and it uses a brush to paint on color. You can change the color in the options, under the Color section.
Figure 3.36 A texture guide created with the 3D Paint tool
A normal map, as described earlier, is a pixel shader that uses light information to calculate very accurate bump mapping in real time. The image is RGB, with the three hues controlling XYZ depth, respectively. One method for creating a normal map is to actually create a high-resolution version of the model in addition to the low-polygon version and baking that information down into a normal map using Maya 6’s new Transfer Surface Information function.
First, you need to create a high polygon version of your game model. Also, your low-polygon model must be UV mapped. For this example, we will use Silenus’s horn (Figure 3.37).
Figure 3.37 A high-resolution version of the horn
| Note: Make sure the plug-in,TransferSurfaceInfo.mll, is loaded under Window > Settings/Preferences > Plug-In Manager. |
Texture painting is definitely a process that depends a lot on talent and practice. Here are some tips to keep in mind while painting your own textures.
Contrast Make sure that your texture is not too subtle. Folds, wrinkles, etc. need to be very clear to be conveyed in the texture. Making sure the image has some contrast can help with this.
Hand Painting versus Photo Sourcing There are two main schools of thought when it comes to creating textures: paint them by hand or use photo sources. Personally, I do both. But even when I use photos of some kind, I rarely use them as is, and I will always try to customize what I take from photos.
The method you use will generally be determined by the style of the game. A game like The Legend of Zelda: The Wind Waker probably would not use much in the way of photo sourcing because of the cartoon style.
Note: A great source for high-resolution photo references is www.3d.sk. |
Saturation Color saturation can depend a lot on the style of the game, but you want to make sure that the nice pretty colors you choose in Photoshop show up nicely on the model.
For the final Silenus model, we have the following textures:
Color Maps The color maps are the main textures that you see with all of the color information (Figure 3.38). These images are mapped to the Color attribute of your materials.
Specular Maps The specular maps are grayscale images with specularity information.
Wherever the model should be shiny, the texture should be white (Figure 3.39). If you use specular maps, you will need to change your Lambert material into one that is capable of specularity, such as a blinn. This is easily done in the material’s Attribute Editor by changing the Type attribute near the top.
Specular maps are mapped to the Specular Color attribute of your materials.
Figure 3.38 The three color maps for Silenus
Figure 3.39 The three specular maps for Silenus
Transparency Maps As mentioned before, transparency maps (or opacity maps) will make a model transparent where the texture is black. White areas will remain opaque (Figure 3.40). Transparency maps are mapped to the Transparency attribute of your materials.
| Note: Maya will automatically apply the alpha channel of your color maps to the Transparency attribute. Maya will automatically apply the alpha channel of your color maps to the Transparency attribute. |
Bump Maps As technology has increased, bump maps have rapidly become replaced with normal maps. But essentially, white areas indicate high, while black areas indicate low. Bump maps are mapped to the Bump Mapping attribute of your materials.
Because this book is not in color, I will not show the bump maps here.
Essentially, they are grayscale versions of the color maps. All of the maps I used can be
found on the CD under Tutorials/Chapter3/Character_UVMapping/sourceimages.
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Created: March 27, 2003
Revised: January 17, 2005
URL: http://webreference.com/graphics/game3/1
