Shaders

Shaders

Shading is a graphical/physics feature used in 3D modelling. There are many types of shading. 3D computer graphics often rely on a simplified reflection model called 'Phong Reflection Model'. In refraction of light, an important concept is the refractive index which is reffered to 'Index of Refraction (IOR)' in most 3D moddeling software applications.

There are many types and ways to do shading on a 3D object. A simple way to shade a model is via texture mapping. Three types of shading, Flat, Goroud and Phong shading are typically used types shading in 3D objects.

Flat Shading: Flat shading is the most processor friendly. However, the problem with it is it looks rather rough and blocky and even kinda outdated. For simpler 3D applications, Flat shading is a good choice.

Goroud Shading: Is more processor intense than flat shading and could take longer to render but it is much more smoother than flat shading. Where flat shading would bring out the polygons when rendered and lighted, Goroud shaded models look very smooth when rendered. It is a very commonly used type of shading.

Phong Shading: Phong Shading requires the most processing power out of all three of the shading types I am talking about. Phong Shading is better than Goroud Shading for when it is applied to a reflection model that has small specular highlights. It also produces an even smoother surface than Goroud Shading.


Comparision of Flat shading, Goraud Shading and Phong Shading.

Another technique of shading is bump mapping. This is a technique I like very much besause it makes 3D objects look more detailed than they actuallly are. It is composed of two textures, the original texture that is the same colour as the texture that would be used on the object and the 'normal map'. The normal map is the main thing behing bump mapping. It is of a different pallete than it's original texture. A convienant way to create one is to download the NVidia Normal Map Filter onto Photoshop. You then load the texture onto photoshop and apply the filter. You can edit the strength of it and you can also preview it in a 3D view to see how it would turn out like.

 

Example of a normal map.


 
 Bump Mapping: Without and With.

Shaders can be added in game engines like Unity. for example, Cel Shading. Cel Shading is a type of shading which gives the models a cartoony look to it. It is used in many games to achieve this look (e.g. No More Heroes, Zelda: The Wind Waker and Borderlands).

Screenshot of No More Heroes. A game which makes use of Cel-Shading.