/**
* graphene_triangle_contains_point:
* @t: a #graphene_triangle_t
* @p: a #graphene_point3d_t
*
* Checks whether the given triangle @t contains the point @p.
*
* Returns: `true` if the point is inside the triangle
*
* Since: 1.2
*/
bool
graphene_triangle_contains_point (const graphene_triangle_t *t,
const graphene_point3d_t *p)
{
graphene_vec3_t point, v1, v2, v3;
float dot_11, dot_12, dot_13;
float dot_22, dot_23;
float inv_denom, u, v;
graphene_point3d_to_vec3 (p, &point);
/* we use the barycoordinates from the given point to check
* if the point is inside the triangle.
*
* see: http://www.blackpawn.com/texts/pointinpoly/default.html
*/
graphene_vec3_subtract (&t->c, &t->a, &v1);
graphene_vec3_subtract (&t->b, &t->a, &v2);
graphene_vec3_subtract (&point, &t->a, &v3);
dot_11 = graphene_vec3_dot (&v1, &v1);
dot_12 = graphene_vec3_dot (&v1, &v2);
dot_13 = graphene_vec3_dot (&v1, &v3);
dot_22 = graphene_vec3_dot (&v2, &v2);
dot_23 = graphene_vec3_dot (&v2, &v3);
inv_denom = 1.f / (dot_11 * dot_22 - dot_12 * dot_12);
u = (dot_22 * dot_13 - dot_12 * dot_23) * inv_denom;
v = (dot_11 * dot_23 - dot_12 * dot_13) * inv_denom;
return (u >= 0.f) && (v >= 0.f) && (u + v < 1.f);
}
/**
* graphene_ray_get_distance_to_point:
* @r: a #graphene_ray_t
* @p: a #graphene_point3d_t
*
* Computes the distance from the origin of the given ray to the given point.
*
* Returns: the distance of the point
*
* Since: 1.4
*/
float
graphene_ray_get_distance_to_point (const graphene_ray_t *r,
const graphene_point3d_t *p)
{
graphene_vec3_t point;
graphene_vec3_t tmp;
float distance;
graphene_point3d_to_vec3 (p, &point);
graphene_vec3_subtract (&point, &r->origin, &tmp);
distance = graphene_vec3_dot (&tmp, &r->direction);
/* the point is behind the ray */
if (distance < 0)
{
graphene_vec3_subtract (&r->origin, &point, &tmp);
return graphene_vec3_length (&tmp);
}
/* get the position on the ray at the given distance */
graphene_vec3_scale (&r->direction, distance, &tmp);
graphene_vec3_add (&tmp, &r->origin, &tmp);
graphene_vec3_subtract (&tmp, &point, &tmp);
return graphene_vec3_length (&tmp);
}
/**
* graphene_triangle_init_from_point3d:
* @t: the #graphene_triangle_t to initialize
* @a: (nullable): a #graphene_point3d_t
* @b: (nullable): a #graphene_point3d_t
* @c: (nullable): a #graphene_point3d_t
*
* Initializes a #graphene_triangle_t using the three given 3D points.
*
* Returns: (transfer none): the initialized #graphene_triangle_t
*
* Since: 1.2
*/
graphene_triangle_t *
graphene_triangle_init_from_point3d (graphene_triangle_t *t,
const graphene_point3d_t *a,
const graphene_point3d_t *b,
const graphene_point3d_t *c)
{
if (a != NULL)
graphene_point3d_to_vec3 (a, &t->a);
else
graphene_vec3_init_from_vec3 (&t->a, graphene_vec3_zero ());
if (b != NULL)
graphene_point3d_to_vec3 (b, &t->b);
else
graphene_vec3_init_from_vec3 (&t->b, graphene_vec3_zero ());
if (c != NULL)
graphene_point3d_to_vec3 (c, &t->c);
else
graphene_vec3_init_from_vec3 (&t->b, graphene_vec3_zero ());
return t;
}
/**
* graphene_ray_init:
* @r: the #graphene_ray_t to initialize
* @origin: (nullable): the origin of the ray
* @direction: (nullable): the direction vector
*
* Initializes the given #graphene_ray_t using the given @origin
* and @direction values.
*
* Returns: (transfer none): the initialized ray
*
* Since: 1.4
*/
graphene_ray_t *
graphene_ray_init (graphene_ray_t *r,
const graphene_point3d_t *origin,
const graphene_vec3_t *direction)
{
if (origin != NULL)
graphene_point3d_to_vec3 (origin, &r->origin);
else
graphene_vec3_init_from_vec3 (&r->origin, graphene_vec3_zero ());
if (direction != NULL)
graphene_vec3_normalize (direction, &r->direction);
else
graphene_vec3_init_from_vec3 (&r->direction, graphene_vec3_zero ());
return r;
}
/**
* graphene_ray_get_closest_point_to_point:
* @r: a #graphene_ray_t
* @p: a #graphene_point3d_t
* @res: (out caller-allocates): return location for the closest point3d
*
* Computes the point on the given #graphene_ray_t that is closest to the
* given point @p.
*
* Since: 1.4
*/
void
graphene_ray_get_closest_point_to_point (const graphene_ray_t *r,
const graphene_point3d_t *p,
graphene_point3d_t *res)
{
graphene_vec3_t point, result;
float distance;
graphene_point3d_to_vec3 (p, &point);
graphene_vec3_subtract (&point, &r->origin, &result);
distance = graphene_vec3_dot (&result, &r->direction);
if (distance < 0)
graphene_vec3_init_from_vec3 (&result, &r->origin);
else
{
graphene_vec3_scale (&r->direction, distance, &result);
graphene_vec3_add (&result, &r->origin, &result);
}
graphene_point3d_init_from_vec3 (res, &result);
}
