ex17-wasm-external.rs

// This the first roguelike-ish example - a walking @. We build a very simple map,
// and you can use the cursor keys to move around a world.
//
// Comments that duplicate previous examples have been removed for brevity.
//////////////////////////////////////////////////////////////

rltk::add_wasm_support!();
use rltk::{Console, GameState, Rltk, VirtualKeyCode, RGB};

// We'll allow map tiles to be either a wall or a floor. We're deriving PartialEq so we don't
// have to match on it every time. We'll make it a copy type because it's really just an int.
#[derive(PartialEq, Copy, Clone)]
#[allow(dead_code)]
enum TileType {
    Wall,
    Floor,
}

// We're extending State to include a minimal map and player coordinates.
struct State {
    map: Vec<TileType>,
    player_position: usize,
}

// We're storing all the tiles in one big array, so we need a way to map an X,Y coordinate to
// a tile. Each row is stored sequentially (so 0..80, 81..160, etc.). This takes an x/y and returns
// the array index.
pub fn xy_idx(x: i32, y: i32) -> usize {
    (y as usize * 80) + x as usize
}

// It's a great idea to have a reverse mapping for these coordinates. This is as simple as
// index % 80 (mod 80), and index / 80
pub fn idx_xy(idx: usize) -> (i32, i32) {
    (idx as i32 % 80, idx as i32 / 80)
}

// Since we have some content, we should also include a map builder. A 'new'
// function is a common Rust way to do this.
impl State {
    #[allow(dead_code)]
    pub fn new() -> State {
        let mut state = State {
            map: vec![TileType::Floor; 80 * 50],
            player_position: xy_idx(40, 25),
        };

        // Make the boundaries walls
        for x in 0..80 {
            state.map[xy_idx(x, 0)] = TileType::Wall;
            state.map[xy_idx(x, 49)] = TileType::Wall;
        }
        for y in 0..50 {
            state.map[xy_idx(0, y)] = TileType::Wall;
            state.map[xy_idx(79, y)] = TileType::Wall;
        }

        // Now we'll randomly splat a bunch of walls. It won't be pretty, but it's a decent illustration.
        // First, obtain the thread-local RNG:
        let mut rng = rltk::RandomNumberGenerator::new();

        for _ in 0..400 {
            // rand provides a gen_range function to get numbers in a range.
            let x = rng.roll_dice(1, 80) - 1;
            let y = rng.roll_dice(1, 50) - 1;
            let idx = xy_idx(x, y);
            // We don't want to add a wall on top of the player
            if state.player_position != idx {
                state.map[idx] = TileType::Wall;
            }
        }

        // We'll return the state with the short-hand
        state
    }

    // Handle player movement. Delta X and Y are the relative move
    // requested by the player. We calculate the new coordinates,
    // and if it is a floor - move the player there.
    pub fn move_player(&mut self, delta_x: i32, delta_y: i32) {
        let current_position = idx_xy(self.player_position);
        let new_position = (current_position.0 + delta_x, current_position.1 + delta_y);
        let new_idx = xy_idx(new_position.0, new_position.1);
        if self.map[new_idx] == TileType::Floor {
            self.player_position = new_idx;
        }
    }
}

// Implement the game loop
impl GameState for State {
    fn tick(&mut self, ctx: &mut Rltk) {
        // Handle keyboard inputs.
        match ctx.key {
            None => {} // Nothing happened
            Some(key) => {
                // A key is pressed or held
                match key {
                    // We're matching a key code from GLFW (the GL library underlying RLTK),
                    // and applying movement via the move_player function.

                    // Numpad
                    VirtualKeyCode::Numpad8 => self.move_player(0, -1),
                    VirtualKeyCode::Numpad4 => self.move_player(-1, 0),
                    VirtualKeyCode::Numpad6 => self.move_player(1, 0),
                    VirtualKeyCode::Numpad2 => self.move_player(0, 1),

                    // Numpad diagonals
                    VirtualKeyCode::Numpad7 => self.move_player(-1, -1),
                    VirtualKeyCode::Numpad9 => self.move_player(1, -1),
                    VirtualKeyCode::Numpad1 => self.move_player(-1, 1),
                    VirtualKeyCode::Numpad3 => self.move_player(1, 1),

                    // Cursors
                    VirtualKeyCode::Up => self.move_player(0, -1),
                    VirtualKeyCode::Down => self.move_player(0, 1),
                    VirtualKeyCode::Left => self.move_player(-1, 0),
                    VirtualKeyCode::Right => self.move_player(1, 0),

                    _ => {} // Ignore all the other possibilities
                }
            }
        }

        // New: Handle web buttons
        if let Some(btn) = &ctx.web_button {
            match btn.trim() {
                "go_nw" => self.move_player(-1, -1),
                "go_n" => self.move_player(0, -1),
                "go_ne" => self.move_player(1, -1),
                "go_w" => self.move_player(-1, 0),
                "go_e" => self.move_player(1, 0),
                "go_sw" => self.move_player(-1, 1),
                "go_s" => self.move_player(0, 1),
                "go_se" => self.move_player(1, 1),
                _ => {}
            }
        }

        // Clear the screen
        ctx.cls();

        // Iterate the map array, incrementing coordinates as we go.
        let mut y = 0;
        let mut x = 0;
        for tile in &self.map {
            // Render a tile depending upon the tile type
            match tile {
                TileType::Floor => {
                    ctx.print_color(
                        x,
                        y,
                        RGB::from_f32(0.5, 0.5, 0.5),
                        RGB::from_f32(0., 0., 0.),
                        ".",
                    );
                }
                TileType::Wall => {
                    ctx.print_color(
                        x,
                        y,
                        RGB::from_f32(0.0, 1.0, 0.0),
                        RGB::from_f32(0., 0., 0.),
                        "#",
                    );
                }
            }

            // Move the coordinates
            x += 1;
            if x > 79 {
                x = 0;
                y += 1;
            }
        }

        // Render the player @ symbol
        let ppos = idx_xy(self.player_position);
        ctx.print_color(
            ppos.0,
            ppos.1,
            RGB::from_f32(1.0, 1.0, 0.0),
            RGB::from_f32(0., 0., 0.),
            "@",
        );
    }
}

#[cfg(target_arch = "wasm32")]
fn main() {
    let context = Rltk::init_simple8x8(
        80,
        50,
        "RLTK Example 17 - WASM External Events",
        "resources",
    );
    let gs = State::new();
    rltk::register_html_button("go_nw");
    rltk::register_html_button("go_n");
    rltk::register_html_button("go_ne");
    rltk::register_html_button("go_w");
    rltk::register_html_button("go_e");
    rltk::register_html_button("go_sw");
    rltk::register_html_button("go_s");
    rltk::register_html_button("go_se");
    rltk::main_loop(context, gs);
}

#[cfg(not(target_arch = "wasm32"))]
fn main() {
    println!("Sorry, this example is intended for Web Assembly (wasm32-unknown-unknown) only.");
    println!("It would actually run in a window, but the purpose is to demonstrate binding to external HTML elements,");
    println!("so there isn't really a lot of point!")
}