This helper function returns the dot product of the specified vectors. DotProduct is part of the suite of extra functionality that is available to C++ programmers who define D3D_OVERLOADS.
D3DVALUE DotProduct (const _D3DVECTOR& v1, const _D3DVECTOR& v2);
This function is defined as follows:
inline D3DVALUE
DotProduct (const _D3DVECTOR& v1, const _D3DVECTOR& v2)
{
return v1.x*v2.x + v1.y * v2.y + v1.z*v2.z;
}