#include <NINJA.H> 
void njSetLightDirection( *ptr, dx, dy, dz )
NJS_LIGHT *ptr
Float dx
Float dy
Float dz

#include <NINJA.H> 
...........

NJS_LIGHT light;

njInitSystem();
njCreateLight(&light, NJD_DIR_LIGHT);
...........
/* 平行光源の光線の方向ベクトルを（１、０、０）に設定 */
njSetLightDirection(&light, 1.f, 0.f, 0.f);