/**
* graphene_quaternion_to_angle_vec3:
* @q: a #graphene_quaternion_t
* @angle: (out): return location for the angle, in degrees
* @axis: (out caller-allocates): return location for the rotation axis
*
* Converts a quaternion into an @angle, @axis pair.
*
* Since: 1.0
*/
void
graphene_quaternion_to_angle_vec3 (const graphene_quaternion_t *q,
float *angle,
graphene_vec3_t *axis)
{
graphene_quaternion_t q_n;
float cos_a;
graphene_quaternion_normalize (q, &q_n);
cos_a = q_n.w;
if (angle != NULL)
*angle = GRAPHENE_RAD_TO_DEG (acosf (cos_a) * 2.f);
if (axis != NULL)
{
float sin_a = sqrtf (1.f - cos_a * cos_a);
if (fabsf (sin_a) < 0.00005)
sin_a = 1.f;
graphene_vec3_init (axis, q_n.x / sin_a, q_n.y / sin_a, q_n.z / sin_a);
}
}
static void
quaternion_operators_normalize (mutest_spec_t *spec)
{
graphene_quaternion_t q1, q2;
graphene_vec4_t v1, v2;
graphene_quaternion_init (&q1, 1.f, 2.f, 3.f, 4.f);
graphene_quaternion_normalize (&q1, &q2);
graphene_vec4_init (&v1, 1.f, 2.f, 3.f, 4.f);
graphene_vec4_normalize (&v1, &v1);
graphene_quaternion_to_vec4 (&q2, &v2);
mutest_expect ("normalizing a quaternion is the same as normalizing the equivalent vec4",
mutest_bool_value (graphene_vec4_near (&v1, &v2, 0.00001f)),
mutest_to_be_true,
NULL);
}
