private static void r_rebound(PhysicActor actor, Rectangle rect, double dt) {
/*
* Employ a heuristic
* ------------
* | 0 |
* | 1 RECT 3 |
* | 2 |
* ------------
*/
actor.set_last_obstacle_collided(rect);
Vector actor_pos = actor.get_position().add(actor.get_velocity().multiply(dt));
Rectangle actor_mbr = actor.get().get_mbr();
double h[] = {
actor_pos.y + actor_mbr.y1 - rect.y2,
actor_pos.y + actor_mbr.y2 - rect.y1,
actor_pos.x + actor_mbr.x2 - rect.x1,
actor_pos.x + actor_mbr.x1 - rect.x2
};
for (int i = 0; i < 4; i++) h[i] = Math.abs(h[i]);
// now the question is - which of those is the smallest?
double smallest_val = Double.POSITIVE_INFINITY;
int smallest_index = -1;
for (int i = 0; i < 4; i++)
if (smallest_val > h[i]) {
smallest_val = h[i];
smallest_index = i;
}
assert (smallest_index != -1);
// ok, smallest_index is that
if (smallest_index == 0) // colliding with floor
Rebound.actor_hit_floor(actor, rect.y2, dt);
if (smallest_index == 1) // colliding with roof
Rebound.actor_hit_roof(actor, rect.y1, dt);
if (smallest_index == 2) {
Rebound.actor_hit_rightside(actor, rect.x1, dt);
if (actor.get_last_obstacle_collided() != rect) {
actor.set_v_braked(true);
actor.set_last_obstacle_collided(rect);
}
}
if (smallest_index == 3) {
Rebound.actor_hit_leftside(actor, rect.x2, dt);
if (actor.get_last_obstacle_collided() != rect) {
actor.set_v_braked(true);
actor.set_last_obstacle_collided(rect);
}
}
}
/**
* Rebound an actor by a platform. Actor must collide with platform.
*
* <p>Can mutate both actor position and velocity. Will not touch anchor nor flags.
*
* @param actor actor (can be mutated)
* @param hs platform
* @param dt time delta
*/
public static void rebound(PhysicActor actor, HorizSegment hs, double dt) {
actor.set_v_braked(true).on_vbrake(actor.get_h_moving());
double actor_x = actor.get_position().x;
double actor_y = hs.y - actor.get().get_mbr().y1 + Rebound.GRAVITY_EPSILON;
actor.set_position(new Vector(actor_x, actor_y));
actor.set_velocity(actor.get_velocity().force_y(0));
// Friction??
if (actor.get_h_moving()) return; // Actor wants to move, no friction
Vector vel = actor.get_velocity();
if (Math.abs(vel.x) < Rebound.FRICTION * dt) vel.x = 0;
else vel.x += -Math.abs(vel.x) / vel.x * Rebound.FRICTION * dt;
actor.set_velocity(vel);
}
/** Modify the actor, as it has hit the floor */
private static void actor_hit_floor(PhysicActor actor, double fy, double dt) {
actor.on_vbrake(actor.get_h_moving());
actor.set_v_braked(true).set_velocity(actor.get_velocity().force_y(0));
actor.set_position(
actor.get_position().force_y(fy - actor.get().get_mbr().y1 + Rebound.GRAVITY_EPSILON));
if (!actor.get_h_moving()) { // consider friction
if (Math.abs(actor.get_velocity().x) < Rebound.FRICTION * dt) {
actor.set_velocity(actor.get_velocity().force_x(0));
actor.on_hbrake();
} else {
actor.set_velocity(
actor
.get_velocity()
.add_x(
-Math.abs(actor.get_velocity().x)
/ actor.get_velocity().x
* Rebound.FRICTION
* dt));
}
}
}