frontfacing

Frontfacing refers to whether a surface, polygon, or object is oriented toward the viewer or camera, with the front side typically defined by the surface normal or the order in which its vertices are listed. The concept is most commonly encountered in computer graphics and 3D modeling, but it also appears in everyday device terminology when describing cameras.

In 3D graphics, a front-facing surface is the side that faces the camera and is considered for visibility, lighting, and shading. Rendering pipelines use front-facing information to perform back-face culling, which discards polygons oriented away from the viewer to optimize rendering. The determination of which winding order (for example, varying between APIs) defines the front face can be configured, and the result may be used by shaders to adjust lighting, visibility, or effects. Surface normals and the view vector are often involved in calculations to decide whether a surface is front-facing in a given frame.

In practice, models may be single-sided or double-sided. Single-sided surfaces render only their front-facing side, while two-sided materials can render both sides, sometimes at the cost of performance or shading complexity. Frontfacing status can also influence interactions in physics engines and collision detections where orientation matters.

In devices, the term front-facing is commonly used to describe cameras that face outward toward the user, as in front-facing or selfie cameras, in contrast with rear-facing cameras.

See also: back-face culling, vertex winding order, surface normals, two-sided materials.