Definition: vertex shader

A programmable function in graphics cards that offers a programmer flexibility in rendering an image. The vertex shader is used to transform the attributes of vertices (points of a triangle) such as color, texture, position and direction from the original color space to the display space. It allows the original objects to be distorted or reshaped in any manner.

From Vertex Shader to Pixel Shader
The output of a vertex shader along with texture maps goes to an interpolation stage and then to the pixel shader. The pixel shader is another programmable function that allows flexibility in shading an individual pixel. Whereas vertex shaders can be used to completely transform the shape of an object, pixel shaders are used to change the appearance of the pixels.

It's About Gaming
Game developers push the envelope for fast graphics rendering and determine the right balance of vertex shading and pixel shading. Sometimes, the pixel shader, which is also called a "fragment shader," performs no processing and acts only as a pass-through.

Introduced in 2001, vertex shaders and pixel shaders are supported by OpenGL and DirectX. See graphics pipeline and graphics accelerator.

Shaders in the Pipeline

Vertex and pixel shaders allow the programmer complete flexibility in rendering an image with regard to reshaping the objects and changing their surfaces. See graphics pipeline for more details.