rust-roguelike-tutorial/chapter-06-monsters/src/player.rs

extern crate rltk;
use rltk::{VirtualKeyCode, Rltk, Point};
extern crate specs;
use specs::prelude::*;
use std::cmp::{max, min};
use super::{Position, Player, Viewshed, TileType, State, Map, RunState};

pub fn try_move_player(delta_x: i32, delta_y: i32, ecs: &mut World) {
    let mut positions = ecs.write_storage::<Position>();
    let mut players = ecs.write_storage::<Player>();
    let mut viewsheds = ecs.write_storage::<Viewshed>();
    let map = ecs.fetch::<Map>();

    for (_player, pos, viewshed) in (&mut players, &mut positions, &mut viewsheds).join() {
        let destination_idx = map.xy_idx(pos.x + delta_x, pos.y + delta_y);
        if map.tiles[destination_idx] != TileType::Wall {
            pos.x = min(79 , max(0, pos.x + delta_x));
            pos.y = min(49, max(0, pos.y + delta_y));

            viewshed.dirty = true;
            let mut ppos = ecs.write_resource::<Point>();
            ppos.x = pos.x;
            ppos.y = pos.y;
        }
    }
}

pub fn player_input(gs: &mut State, ctx: &mut Rltk) -> RunState {
    // Player movement
    match ctx.key {
        None => { return RunState::Paused } // Nothing happened
        Some(key) => match key {
            VirtualKeyCode::Left => try_move_player(-1, 0, &mut gs.ecs),
            VirtualKeyCode::Numpad4 => try_move_player(-1, 0, &mut gs.ecs),
            VirtualKeyCode::H => try_move_player(-1, 0, &mut gs.ecs),
            VirtualKeyCode::Right => try_move_player(1, 0, &mut gs.ecs),
            VirtualKeyCode::Numpad6 => try_move_player(1, 0, &mut gs.ecs),
            VirtualKeyCode::L => try_move_player(1, 0, &mut gs.ecs),
            VirtualKeyCode::Up => try_move_player(0, -1, &mut gs.ecs),
            VirtualKeyCode::Numpad8 => try_move_player(0, -1, &mut gs.ecs),
            VirtualKeyCode::K => try_move_player(0, -1, &mut gs.ecs),
            VirtualKeyCode::Down => try_move_player(0, 1, &mut gs.ecs),
            VirtualKeyCode::Numpad2 => try_move_player(0, 1, &mut gs.ecs),
            VirtualKeyCode::J => try_move_player(0, 1, &mut gs.ecs),
            _ => { return RunState::Paused }
        },
    }
    RunState::Running
}