Add normals to lines
#include <s3d.h>
int s3d_pep_line_normals(int object, const float *nbuf, uint16_t n);
Adds normal information to lines, giving each vertex of a line a normal information. This makes lines somewhat nicer, you'll need that especially when you're going to build wireframe models.
nbuf should contain n * 6 float values, for each vertex a normal vector (x,y,z), and you have 2 vertices for each line so that makes 6 float values per line in total.
Simon Wunderlich
Author of s3d