Materials

A surface can interact with light in many ways; it absorbs, reflects, transmits, refracts or emits light. Dull objects absorb more of the incident light and shiny objects reflect more of the incident light. The scattering of the reflected light by rough surfaces is called diffuse reflection. In addition to diffuse reflection, shiny objects create bright spots when illuminated. This type of reflection is called specular reflection. The polygon surfaces in a 3D model should be associated with materials for calculating how the surfaces and lights interact. The ratio between incoming light intensity and outgoing light intensity is measured as surface reflectance; it is different for different colors, so it is represented as an RGB vector or color, commonly called the surface color. A material (In DirectX or OpenGL) is surface’s reflectance properties for ambient, diffuse and specular lights. In addition, material contains the emissive lighting information of the surface and power of the specular highlight.