use integral_geometry::Size;
use land2d::Land2D;
use std::collections::HashMap;
#[derive(PartialEq, Eq, Hash, Clone, Copy, Debug)]
enum Tile {
Empty,
Outside,
Numbered(u32),
}
impl Tile {
fn is(&self, i: u32) -> bool {
*self == Tile::Numbered(i)
}
fn is_empty(&self) -> bool {
match self {
Tile::Empty => true,
Tile::Outside => true,
_ => false,
}
}
fn is_empty_or(&self, i: u32) -> bool {
match self {
Tile::Numbered(n) => *n == i,
Tile::Empty => true,
_ => false,
}
}
fn is_void_or(&self, i: u32) -> bool {
match self {
Tile::Numbered(n) => *n == i,
_ => true,
}
}
}
impl Default for Tile {
fn default() -> Self {
Tile::Outside
}
}
struct CollapseRule {
to_tile: Tile,
condition: fn([Tile; 4]) -> bool,
}
#[derive(Default)]
struct WavefrontCollapse {
rules: HashMap<Tile, Vec<CollapseRule>>,
}
impl WavefrontCollapse {
pub fn generate_map<I: Iterator<Item = u32>, F: FnOnce(&mut Land2D<Tile>)>(
&mut self,
map_size: &Size,
seed_fn: F,
random_numbers: &mut I,
) -> Land2D<Tile> {
let mut land = Land2D::new(map_size, Tile::Empty);
seed_fn(&mut land);
while self.collapse_step(&mut land, random_numbers) {}
land
}
fn add_rule(&mut self, from_tile: Tile, to_tile: Tile, condition: fn([Tile; 4]) -> bool) {
let rule = CollapseRule { to_tile, condition };
self.rules
.entry(from_tile)
.or_insert_with(Vec::new)
.push(rule);
}
fn collapse_step<I: Iterator<Item = u32>>(
&self,
land: &mut Land2D<Tile>,
random_numbers: &mut I,
) -> bool {
let mut collapse_occurred = false;
for x in 0..land.width() {
for y in 0..land.height() {
let current_tile = land.map(y as i32, x as i32, |p| *p);
if let Some(rules) = self.rules.get(¤t_tile) {
for rule in rules
.iter()
.cycle()
.skip(
random_numbers.next().unwrap_or_default() as usize % (rules.len() + 1),
)
.take(rules.len())
{
let neighbors = self.get_neighbors(&land, x, y);
let have_neighbors = neighbors.iter().any(|t| !t.is_empty());
if have_neighbors && (rule.condition)(neighbors) {
land.map(y as i32, x as i32, |p| *p = rule.to_tile);
collapse_occurred = true;
break;
}
}
}
}
}
collapse_occurred
}
fn get_neighbors(&self, land: &Land2D<Tile>, x: usize, y: usize) -> [Tile; 4] {
[
land.get(y as i32, x as i32 + 1),
land.get(y as i32 + 1, x as i32),
land.get(y as i32, x as i32 - 1),
land.get(y as i32 - 1, x as i32),
]
}
}
#[cfg(test)]
mod tests {
use super::{CollapseRule, Tile, WavefrontCollapse};
use integral_geometry::Size;
use land2d::Land2D;
use std::collections::HashMap;
#[test]
fn test_wavefront_collapse() {
let size = Size::new(4, 4);
let mut rnd = [0u32; 64].into_iter();
let mut wfc = WavefrontCollapse::default();
let empty_land = Land2D::new(&size, Tile::Empty);
let no_rules_land = wfc.generate_map(&size, |l| {}, &mut rnd);
assert_eq!(empty_land.raw_pixels(), no_rules_land.raw_pixels());
wfc.add_rule(Tile::Empty, Tile::Numbered(0), |neighbors| {
neighbors.iter().filter(|&n| *n == Tile::Empty).count() >= 2
});
let ruled_map = wfc.generate_map(&size, |l| {}, &mut rnd);
assert_eq!(ruled_map.raw_pixels(), empty_land.raw_pixels());
}
}