About the em3d_frustum.e class:

a frustum is defined by:

	- fovy, aspect, near_dist, far_dist (perspective)
	- or left, right, bottom, top, near_dist, far_dist (ortho)


there are the following inside tests:

	- insideTest_Point(p: EM_VECTOR3D):INTEGER
		Here a Point p is tested to be in the frustum.


	- insideTest_Sphere(m: EM_VECTOR3D; r: DOUBLE):INTEGER
		A sphere s, given by m and radius r, is used as a bounding box and
		is tested to be in the frustum.


return values of the testing functions:

	-- p or s is completely inside the frustum
	em3d_frustum_inside: INTEGER is 1

	-- there is a intersection with s and the frustom
	-- or p lays on the frustum
	em3d_frustum_intersection: INTEGER is 2

	-- p or s are outside the frustum
	em3d_frustum_outside: INTEGER is 0


unsolved problems:

- the frustum_matrix so far only contains 0's. After initializing this
should not be the case. frustom_matrix is a EM_MATRIX44 and is generated
by emglu_perspective(...) or emgl_ortho(...)

- objects that use the frustum culling before rendering

- generation of bounding boxes