Editing Shading (section)

===Types of lighting===
[[Image:Floodlight.png|frame|right|Shading effects from a [[High-intensity discharge lamp|floodlight]] using a [[ray tracer]]]]
When a shader computes the result color, it uses a [[computer graphics lighting|lighting model]] to determine the amount of light reflected at specific points on the surface. Different lighting models can be combined with different shading techniques — while lighting says how much light is reflected, shading determines how this information is used in order to compute the final result. It may for example compute lighting only at specific points and use [[interpolation]] to fill in the rest. The shader may also decide about how many light sources to take into account etc.

====Ambient lighting====
An ambient light source represents an omnidirectional, fixed-intensity and fixed-color light source that affects all objects in the scene equally (is omnipresent). During rendering, all objects in the scene are brightened with the specified intensity and color. This type of light source is mainly used to provide the scene with a basic view of the different objects in it. This is the simplest type of lighting to implement, and models how light can be scattered or [[reflection (computer graphics)|reflected]] many times, thereby producing a uniform effect.

Ambient lighting can be combined with [[ambient occlusion]] to represent how exposed each point of the scene is, affecting the amount of ambient light it can reflect. This produces diffused, non-directional lighting throughout the scene, casting no clear shadows, but with enclosed and sheltered areas darkened. The result is usually visually similar to an overcast day.

====Point lighting====
Light originates from a single [[point (geometry)|point]] and spreads outward in all directions.

====Spotlighting====
Models a [[Searchlight|spotlight]]: light originates from a single point and spreads outward in a [[cone]].

====Area lighting====
Light originates from a small area on a single [[Plane (mathematics)|plane]]. (A more realistic model than a point light source.)

==== Directional lighting ====
A directional light source illuminates all objects equally from a given [[Direction (geometry)|direction]], like an area light of infinite size and infinite distance from the scene; there is shading, but cannot be any distance falloff. This is like the [[sun]].