Galactica/crates/system/src/phys/systemsim/steputil.rs

use galactica_content::{Content, Relationship, SystemObjectHandle};
use nalgebra::{Isometry2, Point2, Rotation2, Vector2};
use rand::Rng;
use rapier2d::{
	dynamics::RigidBody,
	geometry::{ColliderHandle, Group, InteractionGroups},
};

use crate::{
	data::ShipState,
	phys::{objects::PhysProjectile, ParticleBuilder, PhysStepResources},
};

use super::PhysSim;

// Private methods
impl PhysSim {
	pub(super) fn remove_projectile(
		&mut self,
		res: &mut PhysStepResources,
		c: ColliderHandle,
	) -> Option<(RigidBody, PhysProjectile)> {
		let p = match self.projectiles.remove(&c) {
			Some(p) => p,
			None => return None,
		};
		let r = self
			.rigid_body_set
			.remove(
				p.rigid_body,
				&mut res.wrapper.im,
				&mut self.collider_set,
				&mut res.wrapper.ij,
				&mut res.wrapper.mj,
				true,
			)
			.unwrap();

		return Some((r, p));
	}

	/// Try to land the given ship on the given planet.
	/// State changes on success, and nothing happens on failure.
	/// returns `true` if landing was successful.
	pub(super) fn try_land_ship(
		&mut self,
		ct: &Content,
		collider: ColliderHandle,
		target_handle: SystemObjectHandle,
	) -> bool {
		let ship = self.ships.get_mut(&collider).unwrap();
		let r = self.rigid_body_set.get(ship.rigid_body).unwrap();

		let target = ct.get_system_object(target_handle);
		let t_pos = Vector2::new(target.pos.x, target.pos.y);
		let s_pos = Vector2::new(r.position().translation.x, r.position().translation.y);

		// TODO: deactivate collider when landing.
		// Can't just set_active(false), since we still need that collider's mass.

		// We're in land range...
		if (t_pos - s_pos).magnitude() > target.size / 2.0 {
			return false;
		}

		// And we'll stay in land range long enough.
		if (t_pos - (s_pos + r.velocity_at_point(r.center_of_mass()) * 2.0)).magnitude()
			> target.size / 2.0
		{
			return false;
		}

		let collider = self.collider_set.get_mut(collider).unwrap();
		collider.set_collision_groups(InteractionGroups::new(Group::GROUP_1, Group::empty()));
		ship.data.start_land_on(target_handle);
		return true;
	}

	/// Finish landing this ship on a planet.
	/// Called after the landing animation finishes.
	pub(super) fn finish_land_ship(&mut self, collider: ColliderHandle) {
		let ship = self.ships.get_mut(&collider).unwrap();
		ship.data.finish_land_on();
		let r = self.rigid_body_set.get_mut(ship.rigid_body).unwrap();
		r.set_enabled(false);
		r.set_angvel(0.0, false);
		r.set_linvel(nalgebra::Vector2::new(0.0, 0.0), false);
	}

	pub(super) fn start_unland_ship(&mut self, ct: &Content, collider: ColliderHandle) {
		let ship = self.ships.get_mut(&collider).unwrap();
		let obj = ship.data.get_state().landed_on().unwrap();
		let obj = ct.get_system_object(obj);

		let mut rng = rand::thread_rng();
		let radius = rng.gen_range(500.0..=1500.0);
		let angle = rng.gen_range(0.0..std::f32::consts::TAU);
		let target_offset = Rotation2::new(angle) * Vector2::new(radius, 0.0);
		let target_trans = Vector2::new(obj.pos.x, obj.pos.y) + target_offset;
		let target_pos = Isometry2::new(target_trans, angle);

		ship.data.start_unland_to(ct, target_pos);

		let r = self.rigid_body_set.get_mut(ship.rigid_body).unwrap();
		r.set_enabled(true);
		r.set_position(
			Isometry2::new(Vector2::new(obj.pos.x, obj.pos.y), angle),
			true,
		);
	}

	pub(super) fn finish_unland_ship(&mut self, collider: ColliderHandle) {
		let ship = self.ships.get_mut(&collider).unwrap();
		ship.data.finish_unland_to();
		self.collider_set
			.get_mut(ship.collider)
			.unwrap()
			.set_collision_groups(InteractionGroups::new(
				Group::GROUP_1,
				Group::GROUP_1 | Group::GROUP_2,
			));
	}

	pub(super) fn remove_ship(
		&mut self,
		res: &mut PhysStepResources,
		colliderhandle: ColliderHandle,
	) {
		let ship = match self.ships.get(&colliderhandle) {
			None => return,
			Some(s) => s,
		};

		self.rigid_body_set.remove(
			ship.rigid_body,
			&mut res.wrapper.im,
			&mut self.collider_set,
			&mut res.wrapper.ij,
			&mut res.wrapper.mj,
			true,
		);
		self.ships.remove(&colliderhandle).unwrap();
		self.ship_behaviors.remove(&colliderhandle);
	}

	pub(super) fn collide_projectile_ship(
		&mut self,
		res: &mut PhysStepResources,
		projectile_h: ColliderHandle,
		ship_h: ColliderHandle,
	) {
		let projectile = self.projectiles.get(&projectile_h);
		let ship = self.ships.get_mut(&ship_h);
		if projectile.is_none() || ship.is_none() {
			return;
		}
		let projectile = projectile.unwrap();
		let ship = ship.unwrap();

		let f = res.ct.get_faction(projectile.faction);
		let r = f.relationships.get(&ship.data.get_faction()).unwrap();
		let destory_projectile = match r {
			Relationship::Hostile => match ship.data.get_state() {
				ShipState::Flying { .. } => {
					ship.data.apply_damage(projectile.content.damage);
					true
				}
				ShipState::Collapsing { .. } => true,
				_ => false,
			},
			_ => false,
		};

		if destory_projectile {
			let pr = self.rigid_body_set.get(projectile.rigid_body).unwrap();
			let v =
				pr.velocity_at_point(pr.center_of_mass()).normalize() * projectile.content.force;
			let pos = *pr.translation();
			let _ = pr;

			let r = self.rigid_body_set.get_mut(ship.rigid_body).unwrap();
			r.apply_impulse_at_point(Vector2::new(v.x, v.y), Point2::new(pos.x, pos.y), true);

			// Borrow again, we can only have one at a time
			let pr = self.rigid_body_set.get(projectile.rigid_body).unwrap();
			let pos = *pr.translation();
			let angle = pr.rotation().angle();

			match &projectile.content.impact_effect {
				None => {}
				Some(x) => {
					let effect = res.ct.get_effect(*x);
					let r = ship.rigid_body;
					let sr = self.get_rigid_body(r).unwrap();
					let parent_velocity = pr.velocity_at_point(pr.center_of_mass());
					let target_velocity =
						sr.velocity_at_point(&nalgebra::Point2::new(pos.x, pos.y));

					res.particles.push(ParticleBuilder::from_content(
						effect,
						pos.into(),
						-angle,
						parent_velocity,
						target_velocity,
					));
				}
			};

			self.remove_projectile(res, projectile.collider);
		}
	}
}