game/src/engine/scene.rs

//! This module contains the scene struct which holds everything needed during a game.

use std::time::{Duration, SystemTime};

use crate::engine::bbox::Bbox;
use crate::engine::character::Character;
use crate::engine::input::Action;
use crate::engine::input::InputManager;
use crate::engine::map::{CollisionTile, GraphicTile, Map, PositionedTile};
use crate::engine::object::Object;
use crate::engine::texture::SPRITE_SIZE;
use crate::engine::vector::Vector;

/// Contains everything needed to play.
pub struct Scene {
    /// The characters contained in the scene.
    characters: Vec<Character>,

    /// The objects contained in the scene.
    objects: Vec<Object>,

    /// The map of the scene.
    map: Map,
}

/// The type used to represent whether a a scene is running or finished.
#[derive(Copy, Clone, PartialEq, Eq)]
pub enum State {
    /// The scene is running.
    Running,

    /// The scene is finished.
    Finished,
}

impl Scene {
    /// Creates a scene from a map level.
    pub fn from_map(map: Map) -> Scene {
        let object = Object::new(Vector::new(100.0, 300.0));
        Scene {
            characters: vec![],
            objects: vec![object],
            map,
        }
    }

    /// Adds a character to the scene.
    pub fn add(&mut self, character: Character) {
        let mut character = character;
        character.position.x = self.map.entrance().1 as f64 * SPRITE_SIZE;
        character.position.y = self.map.entrance().0 as f64 * SPRITE_SIZE;

        self.characters.push(character);
    }

    /// Adds an object to the scene.
    pub fn add_object(&mut self, object: Object) {
        self.objects.push(object);
    }

    /// Returns the controlable.
    pub fn controlable(&self) -> Option<&Character> {
        for character in &self.characters {
            if character.controls().is_some() {
                return Some(&character);
            }
        }
        None
    }

    /// Returns the controlable.
    pub fn controlable_mut(&mut self) -> Option<&mut Character> {
        for character in &mut self.characters {
            if character.controls().is_some() {
                return Some(character);
            }
        }
        None
    }

    /// Returns the right view.
    pub fn view(&self) -> Option<Bbox> {
        let view = self.controlable()?.view();
        let mut center = view.position + view.size / 2.0;
        let size = view.size;

        // Clamp center so that the view doesn't show things outside the level.
        if center.x - size.x / 2.0 < 0.0 {
            center.x = size.x / 2.0;
        }

        if center.y - size.y / 2.0 < 0.0 {
            center.y = size.y / 2.0;
        }

        let right_limit = self.map.cols() as f64 * SPRITE_SIZE;
        let bottom_limit = self.map.rows() as f64 * SPRITE_SIZE;

        if center.x + size.x / 2.0 > right_limit {
            center.x = right_limit - size.x / 2.0;
        }

        if center.y + size.y / 2.0 > bottom_limit {
            center.y = bottom_limit - size.y / 2.0;
        }

        Some(Bbox::from_center_and_size(center, size))
    }

    /// Updates the whole scene.
    pub fn update(&mut self, now: SystemTime, duration: Duration, inputs: &InputManager) -> State {
        let mut state = State::Running;

        for c in &mut self.characters {
            // Don't need to update if the character is dead
            // if c.is_alive() {
            if true {
                let old = c.bbox();

                // Compute the offset between position and bbox
                let offset = old.position - c.position;

                c.update(now, duration, inputs);

                if let Some((axis, position, damage)) = self.map.collides_bbox(old, c.bbox()) {
                    c.position = position - offset;
                    if axis.is_x() {
                        c.speed.x = 0.0;
                    }

                    if axis.is_y() {
                        c.speed.y = 0.0;
                        c.ground_collision();
                    }

                    if damage {
                        c.die();
                        state = State::Finished;
                    }
                } else {
                    c.fall_off();
                }

                for object in &self.objects {
                    let positioned = PositionedTile {
                        graphic: GraphicTile(None),
                        collision: CollisionTile::full(),
                        position: object.position,
                    };

                    if let Some((axis, position)) = positioned.collides(old, c.bbox()) {
                        c.position = position - offset;
                        if axis.is_x() {
                            c.speed.x = 0.0;
                        }

                        if axis.is_y() {
                            c.speed.y = 0.0;
                            c.ground_collision();
                        }
                    }
                }
            }
        }

        state
    }

    /// Transfers an action to the elements contained in the scene that should receive actions.
    pub fn manage_action(&mut self, action: Action) {
        for c in &mut self.characters {
            c.manage_action(action);
        }
    }

    /// Returns a reference to the characters of the scene.
    pub fn characters(&self) -> &Vec<Character> {
        &self.characters
    }

    /// Returns a reference to the map.
    pub fn map(&self) -> &Map {
        &self.map
    }

    /// Returns a reference to the objects of the scene.
    pub fn objects(&self) -> &Vec<Object> {
        &self.objects
    }
}

/// Trait that needs to be implemented for everything that can be updatable.
pub trait Updatable {
    /// Updates the thing depending on the duration since last frame.
    fn update(&mut self, now: SystemTime, duration: Duration, inputs: &InputManager);

    /// Called when an action arrives.
    fn manage_action(&mut self, action: Action);
}