hi there. well, i have a problem, that i am almost sure it cannot be solved, but i want to ask u first, because i’m just human . so:

in 3d studio max, there is a notion called smoothing group. for those who don’t know about it, i will try to explain. faces can be part of so called “smoothing groups”. vertex normals of the vertices in the same smoothing groups are calculated by interpolating the normals from the 3 adiacent triangles that share the vertex. on the other hand, the vertices which are shared by triangles from different smoothing groups have 2 normal vectors, one for each group. if this 2 groups are rendered separately, when lighted those 2 normals generate a sharp edge. if all 3 triangles that share a vertex are from 3 different smoothing groups, then there will be 3 normal vectors/vertex there is the case of a cube, where vertices are making triaedral(sory for bad english) angles.

so my problem is: can we implement multiple vertex normals in OpenGL using Vertex Arrays? if u find a solution please let me know.

if u don’t have any solution then here is a discussion topic:

SHOULDN’T BE IMPLEMENTED IN OPENGL MULTIPLE VERTEX_NORMAL ARRAYS, LIKE TEXTURES, TO SUPPORT UP TO THREE VERTEX NORMALS PER VERTEX?

thank you for your patience and i’m looking forward for your answer