Thread: Checking for a point inside a region of a spherical surface

Hi everybody,

I am working on a 3D Morphing algorithm.

I have a point X on lying on a unit sphere in the spherical coordinate system. I have three other points A,B, and C which are also on the unit sphere. The sphere is centered at the origin.

I need to find out whether X lies on the spherical 'triangular' area enclosed by A,B, and C or not.

Can any one tell me how to do this?

Thanks a lot in advance.