fixes to biome blending

engine/world_generation/src/map/biome_map.rs

@@ -1,54 +1,59 @@
 use bevy::math::UVec2;
+use rayon::iter::{IntoParallelIterator, IntoParallelRefIterator, ParallelIterator};
 
 use super::chunk::Chunk;
 
 pub struct BiomeMap {
 	pub height: usize,
 	pub width: usize,
-	pub chunks: Vec<[Vec<f32>; Chunk::AREA]>,
+	pub biome_count: usize,
+	pub tiles: Vec<Vec<f32>>,
 }
 
 impl BiomeMap {
-	pub fn new(size: UVec2) -> Self {
+	pub fn new(size: UVec2, biome_count: usize) -> Self {
 		return BiomeMap {
-			height: size.y as usize,
-			width: size.x as usize,
-			chunks: Vec::with_capacity(size.length_squared() as usize),
+			height: size.y as usize * Chunk::SIZE,
+			width: size.x as usize * Chunk::SIZE,
+			biome_count,
+			tiles: Vec::with_capacity(size.x as usize * size.y as usize * Chunk::AREA),
 		};
 	}
 
 	pub fn blend(&mut self, count: usize) {
+		assert!(count != 0, "Count cannot be 0");
 		for _ in 0..count {
 			self.blend_once();
 		}
 	}
 
 	fn blend_once(&mut self) {
-		for y in 0..self.height {
+		let t: Vec<_> = (0..self.height)
+			.into_par_iter()
+			.map(|y| {
+				let mut new_tiles = Vec::with_capacity(self.width);
 				for x in 0..self.width {
 					let kernel = self.get_kernel(x as i32, y as i32);
-				let r = kernel.iter().filter_map(|f| *f).fold(Vec::new(), |a, b| {
-					if a.len() != b.len() {
-						return b.iter().map(|f| *f).collect();
-					}
+					let r = kernel
+						.iter()
+						.filter_map(|f| *f)
+						.fold(vec![0.; self.biome_count], |a, b| {
 							return a.iter().zip(b).map(|v| v.0 + v.1).collect();
 						});
 
 					let sum: f32 = r.iter().sum();
+					if sum == 0. {
+						new_tiles.push(vec![0.; self.biome_count]);
+						continue;
+					}
+					new_tiles.push(r.iter().map(|f| f / sum).collect());
+				}
+				return new_tiles;
+			})
+			.flatten()
+			.collect();
 
-				*self.get_biome_mut(x, y) = r.iter().map(|f| f / sum).collect();
-			}
-		}
-	}
-
-	fn get_biome_mut(&mut self, x: usize, y: usize) -> &mut Vec<f32> {
-		let cx = x as usize / Chunk::SIZE;
-		let cy = y as usize / Chunk::SIZE;
-		let chunk_index = cy * self.width as usize + cx;
-		let ix = x as usize - (x as usize * Chunk::SIZE);
-		let iy = y as usize - (y as usize * Chunk::SIZE);
-		let index = iy * self.width as usize + ix;
-		return &mut self.chunks[chunk_index][index];
+		self.tiles = t;
 	}
 
 	pub fn get_kernel(&self, x: i32, y: i32) -> [Option<&Vec<f32>>; 9] {
@@ -73,12 +78,30 @@ impl BiomeMap {
 			return None;
 		}
 
-		let cx = x as usize / Chunk::SIZE;
-		let cy = y as usize / Chunk::SIZE;
-		let chunk_index = cy * self.width as usize + cx;
-		let ix = x as usize - (x as usize * Chunk::SIZE);
-		let iy = y as usize - (y as usize * Chunk::SIZE);
-		let index = iy * self.width as usize + ix;
-		return Some(&self.chunks[chunk_index][index]);
+		return Some(&self.tiles[x as usize + y as usize * self.width]);
+	}
+}
+
+#[cfg(test)]
+mod tests {
+
+	use super::*;
+
+	#[test]
+	fn biome_blend() {
+		let mut biome = BiomeMap::new(UVec2::ONE * 16, 8);
+
+		for y in 0..biome.height {
+			for x in 0..biome.width {
+				let mut b = vec![0.; biome.biome_count];
+				let i = x / Chunk::SIZE;
+				let z = y / Chunk::SIZE;
+				let idx = (i + z) % biome.biome_count;
+				b[idx] = 1.;
+				biome.tiles.push(b);
+			}
+		}
+
+		biome.blend(8);
 	}
 }