When texturing a 3D surface or surfaces (a process known as
texture mapping), the
renderer maps texels to appropriate pixels in the geometric fragment (typically a triangle) in the output picture. On modern computers, this operation is accomplished on the
graphics processing unit. The texturing process starts with a location in space. The location can be in world space, but typically it is local to a model space so that the texture moves with the model. A projector function is applied to the location to change the location from a three-element vector (\left (x,y,z \right )) to a two-element (\left (u,v\right )) vector with values ranging from zero to one (
uv). These values are multiplied by the resolution of the texture to obtain the location of the texel. When a texel is requested that is not on an
integer position,
texture filtering is applied. When a texel is requested that is outside of the texture, one of two techniques is used: clamping or wrapping.
Clamping limits the texel to the texture size, moving it to the nearest edge if it is more than the texture size.
Wrapping moves the texel in increments of the texture's size to bring it back into the texture. Wrapping causes a texture to be repeated; clamping causes it to be in one spot only. ==See also==