//面面求交
Line plane_intersection(const Plane &u, const Plane &v)
{
Line ret;
ret.a = (line_to_plane(Line(v.a, v.b), u) == 0)
? line_plane_intersection(Line(v.b, v.c), u)
: line_plane_intersection(Line(v.a, v.b), u);
ret.b = (line_to_plane(Line(v.c, v.a), u) == 0)
? line_plane_intersection(Line(v.b, v.c), u)
: line_plane_intersection(Line(v.a, v.c), u);
return ret;
}
bool hitscan_sprite_mobs(const Vec3& position, const Vec3& direction, float range,
SpriteMobID& id, float& distance, Vec3& collision_point)
{
SpriteMobID nearest_mob = NULL_SPRITE_MOB;
float nearest_distance = 100000.0f;
Vec3 nearest_collision_point = vec3_init(0);
const float range_sq = range * range;
const Vec3 up = vec3_init(0, 0, 1);
for (size_t i=0, j=0; i<sprite_mob_list->max && j<sprite_mob_list->count; i++)
{ // TODO
// do a line-plane intersection test against the mob, if its in frustum
SpriteMob* m = sprite_mob_list->objects[i];
if (m == NULL) continue;
j++;
Vec3 p = m->get_center();
p = quadrant_translate_position(position, p);
if (vec3_distance_squared(position, p) > range_sq)
continue;
float rad_sq = 10000.0f;
Vec3 line_point = vec3_init(0);
if (!sphere_line_distance(position, direction, p, line_point, rad_sq))
continue;
Vec3 forward = vec3_sub(position, p);
forward.z = 0.0f;
if (unlikely(vec3_length_squared(forward) == 0))
continue;
forward = vec3_normalize(forward);
const Vec3 right = vec3_normalize(vec3_cross(forward, up));
float d = 1000000.0f;
float width = get_mob_width(m->type) * 0.5f;
float height = get_mob_height(m->type) * 0.5f;
if (!line_plane_intersection(position, direction, p, width, height,
forward, right, up, d))
continue;
if (d >= nearest_distance)
continue;
nearest_distance = d;
nearest_mob = m->id;
nearest_collision_point = line_point;
}
id = nearest_mob;
distance = nearest_distance;
collision_point = translate_position(nearest_collision_point);
return (nearest_mob != NULL_SPRITE_MOB);
}