Unity 5 introduced a new shader, called Default Shader, that have the most needed options for texturing an object.
This tutorial will show how to texture a simple low-poly ark (only 52 faces) using textures made with only one image editiong software, even the special Normal Map.
The original object in Blender. Low poly with UV mapping for textures (one for the box, other for the lid):
This is the Default Shader with its options.
Above, the ark with only the difuse texture (colors) applied to the Albedo option of the shader. Below the texture made in Manga Studio, a software created to work with comics/mangas. It have tools to painting and drawing, but no effects like Phostoshop.
This texture was created with different layers, that can help later to create the other types of textures, once some details can change or can be removed. All the textures was made in the same file, divided into folders to maintain the layers organized.
So, any software for digital painting can be used to create textures, even the Normal Map. You don’t need a special software to create this one, or Photoshop with plug-ins. Unity will create the Normal for you from a grayscale texture.
Below is the ark now with the Normal map applied. See that the yellow part and the celtic accents have relief? This is the function of the Normal Map, create details without increasing the number of polygons of the model. In games you need to control how much polygons the entire scene have, to maintain a good performance.
With the Normal map ypu can used the Heightmap too. This one needs more computation, so use it only when really need, on stone walls as example. Once we don’t need too much high relief in the ark, it isn’t used here.
The Normal and Height maps can use the same grayscale image. Below the map in Manga Studio. The black indicates low areas, or not relief, and white the high relief areas:
This grayscale image is imported to Unity. And, in the import options for the texture, we create the Normal. See how to do it:
In Texture Type, select Advanced. In Import Type, select Normal Map. And then Apply, the texture will change to Normal Map. Play with the Filtering and Bumpiness to achieve the desired result.
The ark is made of wood (brown) and metal (yellow). But we have a model with no smoothness or shininess. To correct it we use another texture. The texture is applied to Metallic slot and substitute the options:
Note the shining and snoothness depend of the lights in the scene. In the video, where the ark is spinning, you can see some light reflections in the metal part.
Above the texture in Manga Studio. This texture tells to shader where the model is smooth (alpha channel) and where it is shinning (red channel). If your image is a simple grayscale, in Import options select Advanced, then check the option Alpha from Gray. This will make the texture ready to use in the Metallic option.
Now, to achieve a better result, we need to darken the ark interior, once the light doesn’t incide here directly. Remember the first image of the ark? The interior is lighten as the exterior. One way to darken is to paint the interior in Difuse texture with a darker color, but the light wil continue to incide here, and the darker color will be highlighted. We don’t want it. The other way (as I can say, the correct one) is telling to shader the areas that can receive light, and the others that can’t. This is made with an occlusion map. Bellow is the ark with the occlusion applied to it.
And the occlusion, that uses a grayscale map too, where white indicates light incidence, and black no light.
You can use any image editing softwate to make the textures. This is a good thing for who is making a low budget game with simple objects. A software like GIMP, Paint.Net, or even one made for vector drawing, like Manga Studio used here, or CorelDraw, can be used.
The wood texture I made using a combination of the texture of real wood from CGTextures and a base solid color. For this, I paint the solid color that I want to the wood in one layer, then put the wood texture in another layer (above), turn the wood texture grayscale and change the layer mode to Overlay.
And the video:
For more information about the Default Shader and texture types, see Unity3D documentation: http://docs.unity3d.com/Manual/StandardShaderMaterialParameters.html