Suppose you know the three vertices for a spherical triangle. 
Then how do you draw the sides on a sphere in 3D?
I need some python code to use in Blender 3d modelisation software.
I already have the sphere done in 3D in Blender.
Thanks & happy blendering.
note  1:
i have the 3 points / vertices (p1,p2,p3 ) on the sphere for a spherical triangle
but i need to trace the edges  on the sphere in 3D
so what would be the equations needed to determine  all vertices  between each points pair of the triangle on the sphere
3 edges  from p1 to p2  -  p2 to p3  and o3  to p1
i know it has something to do with the Great circle   for Geodesic  on a sphere
but cannot   find the proper equations to do the calculations in spherical coordinates!
Thanks

Great circles
it   would  have been interesting to see a solution with great circle and see tehsolution in spherical coordinates directly !
but still interesting to do it in the euclidiens space 
Thanks 

ok i used this idea of line segment between 2 points 
but did not do it as  indicated before
i used an alternative method - Bezier line interpolation**
i parametrize the line with a bezier line
then subdivided  and calculated as shonw ealier the ratio and angle for each of the subdivided bezier point on the chord
and it works very well and very precise 
but it would be interesting to see how it is done whit the earlier method
but not certain how to do the iteration loop?
how do you load up the python code  here
just past it  with Ctrl-V?
Thanks and happy 2.5

i do use the blenders' forum
but no guaranti to get a clear answer all the time!
that's why i tried here - took a chance
i did the first edge seems to work 
now got to make a loop to  get  multi segment for first edge and then do the other edges also
2- other subject
  i open here a post on bezier triangle patch
 i know it's not a usfull tool
but just to show how it is done
have youeseen a python sript to do theses triangel patch
and i did ask this questin on blender's foum and no answer
also on IRC python and sems to be dead right now 
probably guys are too busy finishing the 2.5 Beta vesion which should come out  in a week or 2
Hey Thanks a lot  for this math discussion 
if i have problem be back tomorrow
happy math and 2.5
One cheap and easy method for doing this would be to create the triangle and subdivide the faces down to the level of detail you want, then normalize all the vertices to the radius you want.
How to draw a spherical triangle on a sphere in 3D?