Camera Frustrum Calculation

The frustum is a basic item in any game engine. Unity have a function to calculate the frustum planes for a given camera, CalculateFrustumPlanes and another, TestPlanesAABB which together can be used to check if some object is inside the frustum. But there is an easier feature already included, Renderer.isVisible, which tells if an object is in the frustum of any camera. If you have only one camera, this will be easier to use - but if you plan to use an auxiliary camera to render only what the main camera sees, it will not work because both frustum will be taken into account.