// Return true if object A is expected to collide with object B within time duration
// For purposes of this check, the first object moves from current location to predicted
// location. The second object is assumed to be where it will be at time duration, NOT
// where it currently is.
// radius_scale is used to control the precision of the check.
// If 0.0, then use polygon models to perform check, slow and accurate
// If !0.0, then use as a scale on the radius of the objects. 1.0 is Descent style
// collisions. Larger values can be used to be sloppy about the collisions which
// is useful if a moving object wants to prevent a collision.
int objects_will_collide(object *A, object *B, float duration, float radius_scale)
{
object A_future;
vec3d hitpos;
A_future = *A;
vm_vec_scale_add2(&A_future.pos, &A->phys_info.vel, duration);
if (radius_scale == 0.0f) {
return ship_check_collision_fast(B, &A_future, &hitpos );
} else {
float size_A, size_B, dist, r;
vec3d nearest_point;
size_A = A->radius * radius_scale;
size_B = B->radius * radius_scale;
// If A is moving, check along vector.
if (A->phys_info.speed != 0.0f) {
r = find_nearest_point_on_line(&nearest_point, &A->pos, &A_future.pos, &B->pos);
if (r < 0) {
nearest_point = A->pos;
} else if (r > 1) {
nearest_point = A_future.pos;
}
dist = vm_vec_dist_quick(&B->pos, &nearest_point);
return (dist < size_A + size_B);
} else {
return vm_vec_dist_quick(&B->pos, &A->pos) < size_A + size_B;
}
}
}
// Return true if object A is expected to collide with object B within time duration
// For purposes of this check, the first object moves from current location to predicted
// location. The second object is assumed to be where it will be at time duration, NOT
// where it currently is.
// radius_scale is used to control the precision of the check.
// If 0.0, then use polygon models to perform check, slow and accurate
// If !0.0, then use as a scale on the radius of the objects. 1.0 is Descent style
// collisions. Larger values can be used to be sloppy about the collisions which
// is useful if a moving object wants to prevent a collision.
int objects_will_collide(object *A, object *B, float duration, float radius_scale)
{
vec3d prev_pos;
vec3d hitpos;
int ret;
prev_pos = A->pos;
vm_vec_scale_add2(&A->pos, &A->phys_info.vel, duration);
if (radius_scale == 0.0f) {
ret = ship_check_collision_fast(B, A, &hitpos);
} else {
float size_A, size_B, dist, r;
vec3d nearest_point;
size_A = A->radius * radius_scale;
size_B = B->radius * radius_scale;
// If A is moving, check along vector.
if (A->phys_info.speed != 0.0f) {
r = find_nearest_point_on_line(&nearest_point, &prev_pos, &A->pos, &B->pos);
if (r < 0) {
nearest_point = prev_pos;
} else if (r > 1) {
nearest_point = A->pos;
}
dist = vm_vec_dist_quick(&B->pos, &nearest_point);
ret = (dist < size_A + size_B);
} else {
ret = vm_vec_dist_quick(&B->pos, &prev_pos) < size_A + size_B;
}
}
// Reset the position to the previous value
A->pos = prev_pos;
return ret;
}