BoundingFrustum Class
Namespace: Microsoft.Xna.Framework
Assembly: Microsoft.Xna.Framework (in microsoft.xna.framework.dll)
A frustum in computer graphics is generally a volume of 3D space, defined as the part of a rectangular pyramid that lies between two planes perpendicular to its center line. A frustum is often used to represent what a "camera" sees in your 3D space—for example:
The BoundingFrustum class allows you to define a bounding frustum using a combined matrix that is generally the product of a view matrix and a projection matrix.
You can query a BoundingFrustum object for any one of its bounding planes, for its corners, and for whether it intersects with a given object. Since objects that don't intersect with your view frustrum generally don't need to be rendered, culling them quickly can save you a lot of rendering time.