Re: [Mesa3d-users] Orienting Polygons

[Marcelo E. M. <mar...@bi...>]

>> "Wagner, Chad B" <chad.b.wagner@Boeing.com> writes:

 >   I have a similar problem...I want to draw polygons oriented on a
 > plane tangent to a large sphere at the center point of the polygon.

 You want to use basis vectors in spherical coordinates.  e_r is the
 normal to the sphere (and therefore the normal to your plane), e_theta
 and e_phi would help you define the orientation of your quad or
 polygon.  A quick search on google reveals this page:

    http://www.uwm.edu/~norbury/em/node26.html

 It has the transformation matrix you need (alas, this isn't your
 modelview matrix)

-- 
Marcelo