Shading is the proper term for applying a renderable color, surface bumps, transparency, shine, or similar attributes to an object.
In HP Reveal we use four different shaders. Blinn, Phong, Lambert and constant.
Blinn Shaders are more processor intensive than Phong.
Blinn shaders and Phong are the only two shaders which allow the use of specularity in HP Reveal.
However the algorithm used in the Blinn shaders uses more power than phong and without getting into complexities we will say that ends up giving similar results when applied in our 3D engine. Therefore we suggest to avoid the use of Blinn Shaders but work with Phongs instead when the use of either a Specular value or Specular map is required.
Both Blinn and Phong allow for the use of Diffuse maps, Normal maps and Emissive maps.
The Phong material type takes into account the surface curvature, amount of light, and camera angle to get accurate shading and highlights. The algorithm results in tight highlights that are excellent for polished shiny surfaces, such as plastic, porcelain, and glazed ceramic.
Phong Shaders are more processor intensive than Lambert
The biggest difference between these two shaders is the possibility of making use of Specular values; Phong can Lambert can't.
Except specular, Lambert is able to use all other texture maps (Diffuse, Emissive and Normal maps) same as phong.
Lambert is a flat material type that yields a smooth look without highlights. It calculates without taking into account surface shininess, which gives a matte, chalk-like appearance. Lambert material is ideal for surfaces that don't have highlights: pottery, chalk, matte paint, and so forth. If the object should have highlights, though, it's a good idea to use Phong.
Lambert Shaders are more processor intensive than Constant
Last but not least mention the use of Constant shaders. Constant shaders same as with Lambert does not make use of Specular values but at the same time Constant shader do not make use of any other texture maps. Only colour texture, we say colour instead of diffuse as diffuse makes reference to the use of a colour texture to diffuse certain values when shaded with the scene lights, however when a shader is converted to constant it loses the possibility of getting any kind of shade hence why we called it colour instead of diffuse, the shader becomes fully self illuminated and does not make use of the scene light to get the appropriate colour values.
Constant shader could be compared to a Lambert shader with a black tonal range on the colour channel and a colour texture applied to Self-illumination.
Constant shaders work well with baked colour textures.
Matte occluder shader