Normally this is done by testing whether the viewable area (which is
frustum-shaped) intersects with a bounding sphere or bounding box fit to a model. This is much cheaper/quicker than comparing all pixels.
To help with this, XNA provides the
BoundingFrustum class. You basically just create one with the combined View * Projection matrix you're using for your camera, and then you can use it to test a BoundingBox or BoundingSphere for visibility. For Model's, you can just use the BoundingSphere provided by each ModelMesh.
Matt Pettineo | DirectX/XNA MVP
Ride into
The Danger Zone |
PIX With XNA Tutorial
