A shader is a server-side computer program that is used primarily to produce rendering effects on graphics hardware.  As the name implies, shaders can implement lighting and shading effects.  But they are capable of doing much more.

A shader provides an alternative to, and is more flexible than, the fixed function pipeline. 

Through programming, it is possible to create effects with shaders that are difficult or impossible to produce with the fixed function pipeline.
A few examples: 

• Non-linear spatial transformations
• Non-photorealistic rendering
• Per-fragment lighting

Shader gallery

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