question: public static float r_distance ( vec3 a , vec3 b ) { float x = a . m [ 0 ] - b . m [ 0 ] ; float y = a . m [ 1 ] - b . m [ 1 ] ; float z = a . m [ 2 ] - b . m [ 2 ] ; float result = ( float ) Math . sqrt ( x * x + y * y + z * z ) ; return result ; }
target:  \brief distance(vec3 a, vec3 b)