   Help find normal vector
  Is triangle v1,v2,v3 and normals for each vertex n1,n2,n3 and vertex on this triangle p. Need find normal for vertex p! 
  Go to gametutorials.com.  They have a tutorial under the OpenGL Section of their tutorials on how to calculate normals.   Hope this helps. ;  The vertex is somewhere within the triangle?Well, let''s see.The point P can be expressed as (1-f-g)*v1 + (f)*v2 + (g)*v3. ''f'' and ''g'' are known as ''barycentric'' coordinates; they''ll both be greater or equal to 0, and their sum will be less than or equal to 1, because the point is inside the triangle.I think you can find the barycentric coordinates by multiplying (p.x, p.y, p.z) by the inverse of the matrix:v1.x v2.x v3.xv1.y v2.y v3.yv1.z v2.z v3.zwhich should give you the vector1-f-gfgThen, the normal should become:(1-f-g)*n1 + (f)*n2 + (g)*n3I think. I''ve not tested it though. ;  Simple linear interpolation of n1,n2,n3 should do it, too.You can use weighting factors for each vertex normal, dependingon their distance to p.Just a thought, I did this in my first terrain engine and itworked out very well.