Re: Barycentric to cartesian?

Ron Francis wrote:
When finding an intersection of a line and a triangle I find the point on
the plane and then determine if it is in the triangle.
I have been reading some stuff which id supposed to do it more efficiently,
but it leaves me with barycentric coordinates (t,u,v).
I haven't used these before and couldn't find any information on converting
back to cartesian.
Sorry if this is a stupid question, but is it possible?
If so, how can I do it?

Your choice of names for the ordinates suggests you are actually using
the Moller-Trumbore ray-triangle intersection algorithm. In that case,
(t, u, v) are not barycentric coordinates. The barycentric coordinates
are (u, v, 1 - (u + v)), while t is the parameter of the ray. You can
use either to get the point of intersection (t is along the ray, the
barycentric coordinates are along the triangle). Barycentric coordinates
are useful to interpolate values along the triangle, position being just
one example.

--
http://kaba.hilvi.org
.

Relevant Pages

  • Re: Hot to get exactly hit point in Pick?
    ... returned the triangle index and a pair of barycentric coordinates. ... through the vertex buffer/index buffer for your mesh to identify the three ... > Could I get exactly hit point in this triangle? ...
    (microsoft.public.win32.programmer.directx.graphics)
  • Re: vector analysis example question
    ... case the triangle they form). ... The barycentric coordinates of the midpoint of ... t = 0.5 and you have the midpoint. ... and V' = vector parallel to the ...
    (sci.math)
  • Re: Barycentric to cartesian?
    ... the plane and then determine if it is in the triangle. ... but it leaves me with barycentric coordinates. ... the Moller-Trumbore ray-triangle intersection algorithm. ... My apologies, you are right, I was looking at the Moller-Trumbore algorithm ...
    (comp.graphics.algorithms)
  • Re: Hot to get exactly hit point in Pick?
    ... > Could I get exactly hit point in this triangle? ... > Somebody give any sample code is appreciated. ... If you name those 2 barycentric coordinates "u" and "v". ...
    (microsoft.public.win32.programmer.directx.graphics)