LearnOpenGL 总结记录<6> Phong Lighting Model

Lighting in the real world is extremely complicated and depends on way too many factors, something we can’t afford to calculate on the limited processing power we have. Lighting in OpenGL is therefore based on approximations of reality using simplified models that are much easier to process and look relatively similar. These lighting models are based on the physics of light as we understand it. One of those models is called the Phong lighting model. The major building blocks of the Phong model consist of 3 components: ambient, diffuse and specular lighting. Below you can see what these lighting components actually look like:

• Ambient lighting: even when it is dark there is usually still some light somewhere in the world (the moon, a distant light) so objects are almost never completely dark. To simulate this we use an ambient lighting constant that always gives the object some color.

• Diffuse lighting: simulates the directional impact a light object has on an object. This is the most visually significant component of the lighting model. The more a part of an object faces the light source, the brighter it becomes.

• Specular lighting: simulates the bright spot of a light that appears on shiny objects. Specular highlights are often more inclined to the color of the light than the color of the object.