Displacement mapping is an alternative computer graphics technique in contrast to
bump,
normal, and
parallax
Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight and is measured by the angle or semi-angle of inclination between those two lines. Due to foreshortening, nearby object ...
mapping, using a
texture or
height map to cause an effect where the actual geometric position of points over the textured surface are ''displaced'', often along the
local surface normal
In geometry, a normal is an object such as a line, ray, or vector that is perpendicular to a given object. For example, the normal line to a plane curve at a given point is the (infinite) line perpendicular to the tangent line to the curve ...
, according to the value the texture function evaluates to at each point on the surface. It gives surfaces a great sense of depth and detail, permitting in particular self-occlusion,
self-shadowing and silhouettes; on the other hand, it is the most costly of this class of techniques owing to the large amount of additional geometry.
For years, displacement mapping was a peculiarity of high-end rendering systems like
PhotoRealistic RenderMan, while realtime
APIs
Apis or APIS may refer to:
* Apis (deity), an ancient Egyptian god
* Apis (Greek mythology), several different figures in Greek mythology
* Apis (city), an ancient seaport town on the northern coast of Africa
**Kom el-Hisn, a different Egyptian ci ...
, like
OpenGL
OpenGL (Open Graphics Library) is a cross-language, cross-platform application programming interface (API) for rendering 2D and 3D vector graphics. The API is typically used to interact with a graphics processing unit (GPU), to achieve ha ...
and
DirectX
Microsoft DirectX is a collection of application programming interfaces (APIs) for handling tasks related to multimedia, especially game programming and video, on Microsoft platforms. Originally, the names of these APIs all began with "Direc ...
, were only starting to use this feature. One of the reasons for this is that the original implementation of displacement