feat: add chunk blender

pumpkin-util/src/noise/perlin.rs

@@ -226,6 +226,7 @@ impl PerlinNoiseSampler {
 }
 
 /// Data for a single octave in an octave Perlin noise sampler.
+#[derive(Clone)]
 pub struct SamplerData {
     /// The Perlin noise sampler for this octave.
     pub sampler: PerlinNoiseSampler,
@@ -242,6 +243,7 @@ pub struct SamplerData {
 /// Octave noise, also known as fractal noise, combines multiple octaves of Perlin noise
 /// with different frequencies and amplitudes to create more complex, natural-looking patterns.
 /// Each octave adds finer detail to the overall noise.
+#[derive(Clone)]
 pub struct OctavePerlinNoiseSampler {
     /// The list of samplers for each octave, with their associated parameters.
     pub samplers: Box<[SamplerData]>,

pumpkin-util/src/random/mod.rs

@@ -149,23 +149,22 @@ pub fn get_region_seed(world_seed: u64, region_x: i32, region_z: i32, salt: u32)
 /// Carver seeds are used for terrain carving features like caves and ravines.
 ///
 /// # Arguments
-/// - `random` – The random number generator to use.
+/// - `world_seed` – The base world seed (plus carver index).
-/// - `world_seed` – The base world seed.
 /// - `chunk_x` – The X chunk coordinate.
 /// - `chunk_z` – The Z chunk coordinate.
 ///
 /// # Returns
 /// A carver seed for the given chunk.
 #[inline]
-pub fn get_carver_seed(
+#[must_use]
-    random: &mut RandomGenerator,
+pub fn get_carver_seed(world_seed: u64, chunk_x: i32, chunk_z: i32) -> u64 {
-    world_seed: u64,
+    let mut random = LegacyRand::from_seed(world_seed);
-    chunk_x: i32,
+    let l = random.next_i64() | 1;
-    chunk_z: i32,
+    let m = random.next_i64() | 1;
-) -> u64 {
+    ((chunk_x as i64)
-    let x = random.next_i64();
+        .wrapping_mul(l)
-    let z = random.next_i64();
+        .wrapping_add((chunk_z as i64).wrapping_mul(m)) as u64)
-    (chunk_x as u64).wrapping_mul(x as u64) ^ (chunk_z as u64).wrapping_mul(z as u64) ^ world_seed
+        ^ world_seed
 }
 
 #[enum_dispatch]

pumpkin-world/src/chunk/format/mod.rs

@@ -193,6 +193,7 @@ impl ChunkData {
             light_engine: std::sync::Mutex::new(light_engine),
             light_populated: AtomicBool::new(chunk_data.light_correct),
             status: chunk_data.status,
+            blending_data: None,
         })
     }
 

pumpkin-world/src/chunk/mod.rs

@@ -80,6 +80,7 @@ pub struct ChunkData {
     pub light_engine: std::sync::Mutex<ChunkLight>,
     pub light_populated: AtomicBool,
     pub status: ChunkStatus,
+    pub blending_data: Option<crate::generation::blender::blending_data::BlendingData>,
     pub dirty: AtomicBool,
 }
 

pumpkin-world/src/chunk_system/chunk_state.rs

@@ -229,6 +229,7 @@ impl Chunk {
                 light_engine: Mutex::new(ChunkLight::default()),
                 light_populated: AtomicBool::new(false),
                 status: ChunkStatus::Empty,
+                blending_data: None,
                 dirty: AtomicBool::new(false),
             })),
         ) {
@@ -317,6 +318,7 @@ impl Chunk {
             fluid_ticks: Default::default(),
             block_entities: Mutex::new(block_entities),
             status: proto_chunk.stage.into(),
+            blending_data: proto_chunk.blending_data.clone(),
         };
 
         chunk.heightmap = Mutex::new(chunk.calculate_heightmap());

pumpkin-world/src/chunk_system/generation_cache.rs

@@ -323,6 +323,24 @@ impl GenerationCache for Cache {
         }
     }
 
+    fn get_blending_data(
+        &self,
+        chunk_x: i32,
+        chunk_z: i32,
+    ) -> Option<&crate::generation::blender::blending_data::BlendingData> {
+        let dx = chunk_x - self.x;
+        let dz = chunk_z - self.z;
+
+        if dx < 0 || dx >= self.size || dz < 0 || dz >= self.size {
+            return None;
+        }
+
+        match &self.chunks[(dx * self.size + dz) as usize] {
+            Chunk::Proto(chunk) => chunk.blending_data.as_ref(),
+            Chunk::Level(data) => data.blending_data.as_ref(),
+        }
+    }
+
     fn is_air(&self, local_pos: &Vector3<i32>) -> bool {
         is_air(GenerationCache::get_block_state(self, local_pos).0)
     }

pumpkin-world/src/generation/blender/blending_data.rs

@@ -0,0 +1,72 @@
+use pumpkin_data::chunk::Biome;
+
+#[derive(Clone)]
+pub struct BlendingData {
+    pub min_y: i32,
+    pub max_y: i32,
+    // Heights at quart positions (16x16 per chunk)
+    pub heights: Vec<f64>,
+    // Densities at quart positions (16x16 per chunk, but at what Y levels? 1.18+ uses 4 blocks quart)
+    // Simplified: only store for current chunk's Y levels
+    pub densities: Vec<f64>,
+    // Biomes at quart positions (16x16 per chunk)
+    pub biomes: Vec<&'static Biome>,
+}
+
+impl BlendingData {
+    pub fn get_height(&self, cell_x: i32, _cell_y: i32, cell_z: i32) -> f64 {
+        if !(0..16).contains(&cell_x) || !(0..16).contains(&cell_z) {
+            return f64::MAX;
+        }
+        self.heights[(cell_z * 16 + cell_x) as usize]
+    }
+
+    pub fn get_density(&self, cell_x: i32, _cell_y: i32, cell_z: i32) -> f64 {
+        // cell_y is block_y / 8 in Blender.java
+        // We'll need a better storage for this if we want full fidelity
+        if !(0..16).contains(&cell_x) || !(0..16).contains(&cell_z) {
+            return f64::MAX;
+        }
+        // Dummy implementation
+        f64::MAX
+    }
+
+    pub fn iterate_heights<F>(&self, quart_x: i32, quart_z: i32, mut consumer: F)
+    where
+        F: FnMut(i32, i32, f64),
+    {
+        for z in 0..16 {
+            for x in 0..16 {
+                let h = self.heights[z * 16 + x];
+                if h != f64::MAX {
+                    consumer(quart_x + x as i32, quart_z + z as i32, h);
+                }
+            }
+        }
+    }
+
+    pub fn iterate_densities<F>(
+        &self,
+        _quart_x: i32,
+        _quart_z: i32,
+        _min_cell_y: i32,
+        _max_cell_y: i32,
+        _consumer: F,
+    ) where
+        F: FnMut(i32, i32, i32, f64),
+    {
+        // TODO: implement density iteration
+    }
+
+    pub fn iterate_biomes<F>(&self, quart_x: i32, _quart_y: i32, quart_z: i32, mut consumer: F)
+    where
+        F: FnMut(i32, i32, &'static Biome),
+    {
+        for z in 0..16 {
+            for x in 0..16 {
+                let biome = self.biomes[z * 16 + x];
+                consumer(quart_x + x as i32, quart_z + z as i32, biome);
+            }
+        }
+    }
+}

pumpkin-world/src/generation/blender/mod.rs

@@ -1,62 +1,361 @@
-use enum_dispatch::enum_dispatch;
+pub mod blending_data;
+
+use std::f64;
+
+use crate::biome::BiomeSupplier;
+use crate::generation::biome_coords;
+use crate::generation::noise::perlin::DoublePerlinNoiseSampler;
+use crate::generation::noise::router::multi_noise_sampler::MultiNoiseSampler;
+use crate::generation::proto_chunk::GenerationCache;
+use blending_data::BlendingData;
 use pumpkin_data::chunk::Biome;
+use pumpkin_data::noise_parameter::DoublePerlinNoiseParameters;
 use pumpkin_util::math::vector3::Vector3;
+use pumpkin_util::random::xoroshiro128::Xoroshiro;
+use rustc_hash::FxHashMap;
 
-use crate::{
+pub struct BlendingOutput {
-    biome::BiomeSupplier, generation::noise::router::multi_noise_sampler::MultiNoiseSampler,
+    pub alpha: f64,
-};
+    pub blending_offset: f64,
-
-pub struct BlendResult {
-    alpha: f64,
-    offset: f64,
 }
 
-impl BlendResult {
+pub struct Blender {
-    pub const fn new(alpha: f64, offset: f64) -> Self {
+    height_and_biome_blending_data: FxHashMap<u64, BlendingData>,
-        Self { alpha, offset }
+    density_blending_data: FxHashMap<u64, BlendingData>,
-    }
 }
 
-#[enum_dispatch(BlenderImpl)]
+const HEIGHT_BLENDING_RANGE_CELLS: i32 = (7 << 2) - 1; // QuartPos.fromSection(7) - 1
-pub enum Blender {
+const HEIGHT_BLENDING_RANGE_CHUNKS: i32 = (HEIGHT_BLENDING_RANGE_CELLS + 3) >> 2; // QuartPos.toSection(...)
-    NoBlend(NoBlendBlender),
+const DENSITY_BLENDING_RANGE_CELLS: i32 = 2;
-}
+const DENSITY_BLENDING_RANGE_CHUNKS: i32 = 5 >> 2; // QuartPos.toSection(5)
 
 impl Blender {
-    pub const NO_BLEND: Self = Self::NoBlend(NoBlendBlender {});
+    pub fn empty() -> Self {
+        Self {
+            height_and_biome_blending_data: FxHashMap::default(),
+            density_blending_data: FxHashMap::default(),
+        }
+    }
+
+    pub fn of<C: GenerationCache>(cache: &C) -> Self {
+        let center_chunk = cache.get_center_chunk();
+        let center_x = center_chunk.x;
+        let center_z = center_chunk.z;
+
+        let mut height_and_biome_data = FxHashMap::default();
+        let mut density_data = FxHashMap::default();
+
+        let max_dist_sq = (HEIGHT_BLENDING_RANGE_CHUNKS + 1) * (HEIGHT_BLENDING_RANGE_CHUNKS + 1);
+
+        for dx in -HEIGHT_BLENDING_RANGE_CHUNKS..=HEIGHT_BLENDING_RANGE_CHUNKS {
+            for dz in -HEIGHT_BLENDING_RANGE_CHUNKS..=HEIGHT_BLENDING_RANGE_CHUNKS {
+                if dx * dx + dz * dz <= max_dist_sq {
+                    let chunk_x = center_x + dx;
+                    let chunk_z = center_z + dz;
+
+                    if let Some(blending_data) = cache.get_blending_data(chunk_x, chunk_z) {
+                        let packed = (chunk_x as u32 as u64) | ((chunk_z as u32 as u64) << 32);
+                        height_and_biome_data.insert(packed, blending_data.clone());
+
+                        if (-DENSITY_BLENDING_RANGE_CHUNKS..=DENSITY_BLENDING_RANGE_CHUNKS)
+                            .contains(&dx)
+                            && (-DENSITY_BLENDING_RANGE_CHUNKS..=DENSITY_BLENDING_RANGE_CHUNKS)
+                                .contains(&dz)
+                        {
+                            density_data.insert(packed, blending_data.clone());
+                        }
+                    }
+                }
+            }
+        }
+
+        if height_and_biome_data.is_empty() && density_data.is_empty() {
+            Self::empty()
+        } else {
+            Self {
+                height_and_biome_blending_data: height_and_biome_data,
+                density_blending_data: density_data,
+            }
+        }
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.height_and_biome_blending_data.is_empty() && self.density_blending_data.is_empty()
+    }
+
+    pub fn blend_offset_and_factor(&self, block_x: i32, block_z: i32) -> BlendingOutput {
+        let cell_x = biome_coords::from_block(block_x);
+        let cell_z = biome_coords::from_block(block_z);
+
+        let fixed_height = self
+            .get_blending_data_value(cell_x, 0, cell_z, |data, x, y, z| data.get_height(x, y, z));
+
+        if fixed_height != f64::MAX {
+            return BlendingOutput {
+                alpha: 0.0,
+                blending_offset: Self::height_to_offset(fixed_height),
+            };
+        }
+
+        let mut total_weight = 0.0;
+        let mut weighted_heights = 0.0;
+        let mut closest_distance = f64::INFINITY;
+
+        for (&packed_pos, blending_data) in &self.height_and_biome_blending_data {
+            let chunk_x = (packed_pos & 0xFFFFFFFF) as i32;
+            let chunk_z = (packed_pos >> 32) as i32;
+
+            blending_data.iterate_heights(
+                biome_coords::from_chunk(chunk_x),
+                biome_coords::from_chunk(chunk_z),
+                |test_cell_x, test_cell_z, height| {
+                    let dx = (cell_x - test_cell_x) as f64;
+                    let dz = (cell_z - test_cell_z) as f64;
+                    let distance = (dx * dx + dz * dz).sqrt();
+
+                    if distance <= HEIGHT_BLENDING_RANGE_CELLS as f64 {
+                        if distance < closest_distance {
+                            closest_distance = distance;
+                        }
+
+                        let weight = 1.0 / (distance * distance * distance * distance);
+                        weighted_heights += height * weight;
+                        total_weight += weight;
+                    }
+                },
+            );
+        }
+
+        if closest_distance == f64::INFINITY {
+            BlendingOutput {
+                alpha: 1.0,
+                blending_offset: 0.0,
+            }
+        } else {
+            let average_height = weighted_heights / total_weight;
+            let mut alpha =
+                (closest_distance / (HEIGHT_BLENDING_RANGE_CELLS + 1) as f64).clamp(0.0, 1.0);
+            alpha = 3.0 * alpha * alpha - 2.0 * alpha * alpha * alpha;
+            BlendingOutput {
+                alpha,
+                blending_offset: Self::height_to_offset(average_height),
+            }
+        }
+    }
+
+    fn height_to_offset(height: f64) -> f64 {
+        let target_y = height + 0.5;
+        let target_y_mod = target_y.rem_euclid(8.0);
+        (32.0 * (target_y - 128.0) - 3.0 * (target_y - 120.0) * target_y_mod
+            + 3.0 * target_y_mod * target_y_mod)
+            / (128.0 * (32.0 - 3.0 * target_y_mod))
+    }
+
+    pub fn blend_density(&self, block_x: i32, block_y: i32, block_z: i32, noise_value: f64) -> f64 {
+        let cell_x = biome_coords::from_block(block_x);
+        let cell_y = block_y / 8;
+        let cell_z = biome_coords::from_block(block_z);
+
+        let fixed_density =
+            self.get_blending_data_value(cell_x, cell_y, cell_z, |data, x, y, z| {
+                data.get_density(x, y, z)
+            });
+
+        if fixed_density != f64::MAX {
+            return fixed_density;
+        }
+
+        let mut total_weight = 0.0;
+        let mut weighted_densities = 0.0;
+        let mut closest_distance = f64::INFINITY;
+
+        for (&packed_pos, blending_data) in &self.density_blending_data {
+            let chunk_x = (packed_pos & 0xFFFFFFFF) as i32;
+            let chunk_z = (packed_pos >> 32) as i32;
+
+            blending_data.iterate_densities(
+                biome_coords::from_chunk(chunk_x),
+                biome_coords::from_chunk(chunk_z),
+                cell_y - 1,
+                cell_y + 1,
+                |test_cell_x, test_cell_y, test_cell_z, density| {
+                    let dx = (cell_x - test_cell_x) as f64;
+                    let dy = ((cell_y - test_cell_y) * 2) as f64;
+                    let dz = (cell_z - test_cell_z) as f64;
+                    let distance = (dx * dx + dy * dy + dz * dz).sqrt();
+
+                    if distance <= 2.0 {
+                        if distance < closest_distance {
+                            closest_distance = distance;
+                        }
+
+                        let weight = 1.0 / (distance * distance * distance * distance);
+                        weighted_densities += density * weight;
+                        total_weight += weight;
+                    }
+                },
+            );
+        }
+
+        if closest_distance == f64::INFINITY {
+            noise_value
+        } else {
+            let average_density = weighted_densities / total_weight;
+            let alpha = (closest_distance / 3.0).clamp(0.0, 1.0);
+            alpha * noise_value + (1.0 - alpha) * average_density
+        }
+    }
+
+    fn get_blending_data_value<F>(&self, cell_x: i32, cell_y: i32, cell_z: i32, getter: F) -> f64
+    where
+        F: Fn(&BlendingData, i32, i32, i32) -> f64,
+    {
+        let chunk_x = biome_coords::to_chunk(cell_x);
+        let chunk_z = biome_coords::to_chunk(cell_z);
+        let min_x = (cell_x & 3) == 0;
+        let min_z = (cell_z & 3) == 0;
+
+        let mut value = self.get_data_value(&getter, chunk_x, chunk_z, cell_x, cell_y, cell_z);
+        if value == f64::MAX {
+            if min_x && min_z {
+                value =
+                    self.get_data_value(&getter, chunk_x - 1, chunk_z - 1, cell_x, cell_y, cell_z);
+            }
+
+            if value == f64::MAX {
+                if min_x {
+                    value =
+                        self.get_data_value(&getter, chunk_x - 1, chunk_z, cell_x, cell_y, cell_z);
+                }
+
+                if value == f64::MAX && min_z {
+                    value =
+                        self.get_data_value(&getter, chunk_x, chunk_z - 1, cell_x, cell_y, cell_z);
+                }
+            }
+        }
+
+        value
+    }
+
+    fn get_data_value<F>(
+        &self,
+        getter: &F,
+        chunk_x: i32,
+        chunk_z: i32,
+        cell_x: i32,
+        cell_y: i32,
+        cell_z: i32,
+    ) -> f64
+    where
+        F: Fn(&BlendingData, i32, i32, i32) -> f64,
+    {
+        let packed = (chunk_x as u32 as u64) | ((chunk_z as u32 as u64) << 32);
+        if let Some(data) = self.height_and_biome_blending_data.get(&packed) {
+            getter(
+                data,
+                cell_x - biome_coords::from_chunk(chunk_x),
+                cell_y,
+                cell_z - biome_coords::from_chunk(chunk_z),
+            )
+        } else {
+            f64::MAX
+        }
+    }
+
+    pub fn blend_biome(
+        &self,
+        quart_x: i32,
+        quart_y: i32,
+        quart_z: i32,
+        shift_noise: &DoublePerlinNoiseSampler,
+    ) -> Option<&'static Biome> {
+        let mut closest_distance = f64::INFINITY;
+        let mut closest_biome = None;
+
+        for (&packed_pos, blending_data) in &self.height_and_biome_blending_data {
+            let chunk_x = (packed_pos & 0xFFFFFFFF) as i32;
+            let chunk_z = (packed_pos >> 32) as i32;
+
+            blending_data.iterate_biomes(
+                biome_coords::from_chunk(chunk_x),
+                quart_y,
+                biome_coords::from_chunk(chunk_z),
+                |test_cell_x, test_cell_z, biome| {
+                    let dx = (quart_x - test_cell_x) as f64;
+                    let dz = (quart_z - test_cell_z) as f64;
+                    let distance = (dx * dx + dz * dz).sqrt();
+
+                    if distance <= HEIGHT_BLENDING_RANGE_CELLS as f64 && distance < closest_distance
+                    {
+                        closest_biome = Some(biome);
+                        closest_distance = distance;
+                    }
+                },
+            );
+        }
+
+        if closest_distance == f64::INFINITY {
+            None
+        } else {
+            let shift = shift_noise.sample(quart_x as f64, 0.0, quart_z as f64) * 12.0;
+            let alpha = ((closest_distance + shift) / (HEIGHT_BLENDING_RANGE_CELLS + 1) as f64)
+                .clamp(0.0, 1.0);
+            if alpha > 0.5 { None } else { closest_biome }
+        }
+    }
 }
 
 pub struct BlenderBiomeSupplier<'a> {
     base: &'a dyn BiomeSupplier,
+    blender: &'a Blender,
+    shift_noise: DoublePerlinNoiseSampler,
 }
 
 impl BiomeSupplier for BlenderBiomeSupplier<'_> {
     fn biome(&self, x: i32, y: i32, z: i32, sampler: &mut MultiNoiseSampler<'_>) -> &'static Biome {
+        if let Some(blended) = self.blender.blend_biome(x, y, z, &self.shift_noise) {
+            blended
+        } else {
             self.base.biome(x, y, z, sampler)
         }
     }
+}
 
-#[enum_dispatch]
 pub trait BlenderImpl {
-    fn calculate(&self, block_x: i32, block_z: i32) -> BlendResult;
+    fn blend_offset_and_factor(&self, block_x: i32, block_z: i32) -> BlendingOutput;
 
-    fn apply_blend_density(&self, pos: &Vector3<i32>, density: f64) -> f64;
+    fn blend_density(&self, pos: &Vector3<i32>, density: f64) -> f64;
 
-    fn get_biome_supplier<'a>(&self, supplier: &'a dyn BiomeSupplier) -> BlenderBiomeSupplier<'a>;
+    fn get_biome_supplier<'a>(
+        &'a self,
+        supplier: &'a dyn BiomeSupplier,
+    ) -> BlenderBiomeSupplier<'a>;
 }
 
-pub struct NoBlendBlender {}
+impl BlenderImpl for Blender {
-
+    fn blend_offset_and_factor(&self, block_x: i32, block_z: i32) -> BlendingOutput {
-impl BlenderImpl for NoBlendBlender {
+        self.blend_offset_and_factor(block_x, block_z)
-    fn calculate(&self, _block_x: i32, _block_z: i32) -> BlendResult {
-        BlendResult::new(1f64, 1f64)
     }
 
-    fn apply_blend_density(&self, _pos: &Vector3<i32>, density: f64) -> f64 {
+    fn blend_density(&self, pos: &Vector3<i32>, density: f64) -> f64 {
-        density
+        self.blend_density(pos.x, pos.y, pos.z, density)
     }
 
-    fn get_biome_supplier<'a>(&self, supplier: &'a dyn BiomeSupplier) -> BlenderBiomeSupplier<'a> {
+    fn get_biome_supplier<'a>(
-        BlenderBiomeSupplier { base: supplier }
+        &'a self,
+        supplier: &'a dyn BiomeSupplier,
+    ) -> BlenderBiomeSupplier<'a> {
+        let mut random = Xoroshiro::from_seed(42);
+        let shift_noise = DoublePerlinNoiseSampler::from_params(
+            &mut random,
+            &DoublePerlinNoiseParameters::OFFSET,
+            false,
+        );
+        BlenderBiomeSupplier {
+            base: supplier,
+            blender: self,
+            shift_noise,
+        }
     }
 }

pumpkin-world/src/generation/carver/canyon.rs

@@ -17,6 +17,7 @@ impl Carver for CanyonCarver {
         random: &mut RandomGenerator,
         _chunk_pos: &Vector2<i32>,
         carver_chunk_pos: &Vector2<i32>,
+        legacy_random_source: bool,
     ) {
         let CarverAdditionalConfig::Canyon(ref canyon_config) = config.additional else {
             return;
@@ -51,6 +52,7 @@ impl Carver for CanyonCarver {
             0,
             distance,
             y_scale,
+            legacy_random_source,
         );
     }
 }
@@ -71,10 +73,17 @@ impl CanyonCarver {
         step: i32,
         distance: i32,
         y_scale: f64,
+        legacy_random_source: bool,
     ) {
-        let mut random = RandomGenerator::Xoroshiro(
+        let mut random = if legacy_random_source {
-            pumpkin_util::random::xoroshiro128::Xoroshiro::from_seed(tunnel_seed as u64),
+            RandomGenerator::Legacy(pumpkin_util::random::legacy_rand::LegacyRand::from_seed(
-        );
+                tunnel_seed as u64,
+            ))
+        } else {
+            RandomGenerator::Xoroshiro(pumpkin_util::random::xoroshiro128::Xoroshiro::from_seed(
+                tunnel_seed as u64,
+            ))
+        };
         let width_factor_per_height =
             self.init_width_factors(chunk.height() as usize, config, &mut random);
         let mut y_rota = 0.0f32;
@@ -234,8 +243,7 @@ impl CanyonCarver {
                 let zd = (world_z as f64 + 0.5 - z) / horizontal_radius;
 
                 if xd * xd + zd * zd < 1.0 {
-                    let mut has_grass = false;
+                    for world_y in (min_y + 1..=max_y).rev() {
-                    for world_y in (min_y..=max_y).rev() {
                         let yd = (world_y as f64 - 0.5 - y) / vertical_radius;
 
                         if !self.should_skip(
@@ -248,8 +256,7 @@ impl CanyonCarver {
                         ) && !chunk.carving_mask.get(world_x, world_y, world_z)
                         {
                             chunk.carving_mask.set(world_x, world_y, world_z);
-                            has_grass |= self
+                            self.carve_block(chunk, config, world_x, world_y, world_z);
-                                .carve_block(chunk, config, world_x, world_y, world_z, has_grass);
                         }
                     }
                 }
@@ -280,7 +287,6 @@ impl CanyonCarver {
         x: i32,
         y: i32,
         z: i32,
-        mut has_grass: bool,
     ) -> bool {
         let local_y = y - chunk.bottom_y() as i32;
         let state_id = chunk.get_block_state_raw(x & 15, local_y, z & 15);
@@ -290,12 +296,6 @@ impl CanyonCarver {
             return false;
         }
 
-        if block.id == pumpkin_data::Block::GRASS_BLOCK.id
-            || block.id == pumpkin_data::Block::MYCELIUM.id
-        {
-            has_grass = true;
-        }
-
         if config.replaceable.1.contains(&block.id) {
             let air = BlockState::from_id(pumpkin_data::Block::AIR.default_state.id);
             let lava = BlockState::from_id(pumpkin_data::Block::LAVA.default_state.id);
@@ -310,18 +310,6 @@ impl CanyonCarver {
                 chunk.set_block_state(x & 15, local_y, z & 15, air);
             }
 
-            if has_grass {
-                let down_y = y - 1;
-                let local_down_y = down_y - chunk.bottom_y() as i32;
-                if (0..chunk.height() as i32).contains(&local_down_y) {
-                    let down_state_id = chunk.get_block_state_raw(x & 15, local_down_y, z & 15);
-                    if pumpkin_data::Block::from_state_id(down_state_id).id
-                        == pumpkin_data::Block::DIRT.id
-                    {
-                        // dirt replacement skipped
-                    }
-                }
-            }
             return true;
         }
         false

pumpkin-world/src/generation/carver/cave.rs

@@ -16,6 +16,7 @@ impl Carver for CaveCarver {
         random: &mut RandomGenerator,
         _chunk_pos: &Vector2<i32>,
         carver_chunk_pos: &Vector2<i32>,
+        legacy_random_source: bool,
     ) {
         let (is_nether, cave_config) = match config.additional {
             CarverAdditionalConfig::Cave(ref c) => (false, c),
@@ -85,6 +86,7 @@ impl Carver for CaveCarver {
                     if is_nether { 5.0 } else { 1.0 }, // this.getYScale()
                     floor_level,
                     is_nether,
+                    legacy_random_source,
                 );
             }
         }
@@ -151,10 +153,17 @@ impl CaveCarver {
         y_scale: f64,
         floor_level: f64,
         is_nether: bool,
+        legacy_random_source: bool,
     ) {
-        let mut random = RandomGenerator::Xoroshiro(
+        let mut random = if legacy_random_source {
-            pumpkin_util::random::xoroshiro128::Xoroshiro::from_seed(tunnel_seed as u64),
+            RandomGenerator::Legacy(pumpkin_util::random::legacy_rand::LegacyRand::from_seed(
-        );
+                tunnel_seed as u64,
+            ))
+        } else {
+            RandomGenerator::Xoroshiro(pumpkin_util::random::xoroshiro128::Xoroshiro::from_seed(
+                tunnel_seed as u64,
+            ))
+        };
         let split_point = random.next_bounded_i32(dist / 2) + dist / 4;
         let steep = random.next_bounded_i32(6) == 0;
         let mut y_rota = 0.0f32;
@@ -195,6 +204,7 @@ impl CaveCarver {
                     1.0,
                     floor_level,
                     is_nether,
+                    legacy_random_source,
                 );
                 self.create_tunnel(
                     config,
@@ -213,6 +223,7 @@ impl CaveCarver {
                     1.0,
                     floor_level,
                     is_nether,
+                    legacy_random_source,
                 );
                 return;
             }
@@ -301,17 +312,14 @@ impl CaveCarver {
                 let zd = (world_z as f64 + 0.5 - z) / horizontal_radius;
 
                 if xd * xd + zd * zd < 1.0 {
-                    let mut has_grass = false;
+                    for world_y in (min_y + 1..=max_y).rev() {
-                    for world_y in (min_y..=max_y).rev() {
+                        let yd = (world_y as f64 - 0.5 - y) / vertical_radius;
-                        let yd = (world_y as f64 + 0.5 - y) / vertical_radius;
 
                         if !self.should_skip(xd, yd, zd, floor_level)
                             && !chunk.carving_mask.get(world_x, world_y, world_z)
                         {
                             chunk.carving_mask.set(world_x, world_y, world_z);
-                            has_grass |= self.carve_block(
+                            self.carve_block(chunk, config, world_x, world_y, world_z, is_nether);
-                                chunk, config, world_x, world_y, world_z, is_nether, has_grass,
-                            );
                         }
                     }
                 }
@@ -336,7 +344,6 @@ impl CaveCarver {
         y: i32,
         z: i32,
         is_nether: bool,
-        mut has_grass: bool,
     ) -> bool {
         let local_y = y - chunk.bottom_y() as i32;
         let state_id = chunk.get_block_state_raw(x & 15, local_y, z & 15);
@@ -346,12 +353,6 @@ impl CaveCarver {
             return false;
         }
 
-        if block.id == pumpkin_data::Block::GRASS_BLOCK.id
-            || block.id == pumpkin_data::Block::MYCELIUM.id
-        {
-            has_grass = true;
-        }
-
         // Only carve if it's replaceable
         if config.replaceable.1.contains(&block.id) {
             // Replace with air or lava
@@ -372,19 +373,6 @@ impl CaveCarver {
                 chunk.set_block_state(x & 15, local_y, z & 15, air);
             }
 
-            if has_grass {
-                let down_y = y - 1;
-                let local_down_y = down_y - chunk.bottom_y() as i32;
-                if (0..chunk.height() as i32).contains(&local_down_y) {
-                    let down_state_id = chunk.get_block_state_raw(x & 15, local_down_y, z & 15);
-                    if pumpkin_data::Block::from_state_id(down_state_id).id
-                        == pumpkin_data::Block::DIRT.id
-                    {
-                        // dirt replacement skipped
-                    }
-                }
-            }
-
             return true;
         }
         false

pumpkin-world/src/generation/carver/mod.rs

@@ -17,14 +17,11 @@ pub trait Carver {
         random: &mut RandomGenerator,
         chunk_pos: &Vector2<i32>,
         carver_chunk_pos: &Vector2<i32>,
+        legacy_random_source: bool,
     );
 }
 
 pub fn carve(chunk: &mut ProtoChunk, generator: &VanillaGenerator) {
-    let mut random = RandomGenerator::Xoroshiro(
-        pumpkin_util::random::xoroshiro128::Xoroshiro::from_seed(generator.random_config.seed),
-    );
-
     // Vanilla applyCarvers uses a range of 8 chunks (17x17 area)
     let radius = 8;
     let chunk_x = chunk.x;
@@ -32,7 +29,6 @@ pub fn carve(chunk: &mut ProtoChunk, generator: &VanillaGenerator) {
     let chunk_pos = Vector2::new(chunk_x, chunk_z);
 
     let overworld_carvers = [&CAVE, &CAVE_EXTRA_UNDERGROUND, &CANYON];
-
     let nether_carvers = [&NETHER_CAVE];
 
     let carvers_to_use = if generator.dimension == pumpkin_data::dimension::Dimension::OVERWORLD {
@@ -56,14 +52,19 @@ pub fn carve(chunk: &mut ProtoChunk, generator: &VanillaGenerator) {
             // maintain the random seed logic.
             for (index, &config) in carvers_to_use.iter().enumerate() {
                 let seed = get_carver_seed(
-                    &mut random,
                     generator.random_config.seed + index as u64,
                     carver_x,
                     carver_z,
                 );
-                let mut carver_random = RandomGenerator::Xoroshiro(
+                let mut carver_random = if generator.settings.legacy_random_source {
+                    RandomGenerator::Legacy(
+                        pumpkin_util::random::legacy_rand::LegacyRand::from_seed(seed),
+                    )
+                } else {
+                    RandomGenerator::Xoroshiro(
                         pumpkin_util::random::xoroshiro128::Xoroshiro::from_seed(seed),
-                );
+                    )
+                };
 
                 if should_carve(config, &mut carver_random) {
                     match config.additional {
@@ -74,6 +75,7 @@ pub fn carve(chunk: &mut ProtoChunk, generator: &VanillaGenerator) {
                                 &mut carver_random,
                                 &chunk_pos,
                                 &carver_chunk_pos,
+                                generator.settings.legacy_random_source,
                             );
                         }
                         CarverAdditionalConfig::Canyon(_) => {
@@ -83,6 +85,7 @@ pub fn carve(chunk: &mut ProtoChunk, generator: &VanillaGenerator) {
                                 &mut carver_random,
                                 &chunk_pos,
                                 &carver_chunk_pos,
+                                generator.settings.legacy_random_source,
                             );
                         }
                     }

pumpkin-world/src/generation/mod.rs

@@ -1,7 +1,7 @@
 #![allow(dead_code)]
 
 mod biome;
-mod blender;
+pub mod blender;
 mod block_predicate;
 mod block_state_provider;
 pub mod carver;

pumpkin-world/src/generation/noise/perlin.rs

@@ -1,6 +1,7 @@
 use pumpkin_data::chunk::DoublePerlinNoiseParameters;
 use pumpkin_util::{noise::perlin::OctavePerlinNoiseSampler, random::RandomImpl};
 
+#[derive(Clone)]
 pub struct DoublePerlinNoiseSampler {
     first_sampler: OctavePerlinNoiseSampler,
     second_sampler: OctavePerlinNoiseSampler,

pumpkin-world/src/generation/proto_chunk.rs

@@ -85,6 +85,11 @@ pub trait GenerationCache: HeightLimitView + BlockAccessor {
     fn ocean_floor_height_exclusive(&self, x: i32, z: i32) -> i32;
     fn is_air(&self, local_pos: &Vector3<i32>) -> bool;
     fn get_biome_for_terrain_gen(&self, x: i32, y: i32, z: i32) -> &'static Biome;
+    fn get_blending_data(
+        &self,
+        chunk_x: i32,
+        chunk_z: i32,
+    ) -> Option<&crate::generation::blender::blending_data::BlendingData>;
 }
 
 const AIR_BLOCK: Block = Block::AIR;
@@ -169,6 +174,7 @@ pub struct ProtoChunk {
     pub stage: StagedChunkEnum,
     pub light: ChunkLight,
     pub carving_mask: crate::generation::carver::mask::CarvingMask,
+    pub blending_data: Option<crate::generation::blender::blending_data::BlendingData>,
     /// Block entities pending creation when the chunk is finalized.
     /// These are created from structure templates during world generation.
     pub pending_block_entities: Vec<NbtCompound>,
@@ -251,6 +257,7 @@ impl ProtoChunk {
                 height as i32,
                 dimension.min_y,
             ),
+            blending_data: None,
             pending_block_entities: Vec::new(),
         }
     }
@@ -262,6 +269,7 @@ impl ProtoChunk {
         let mut proto_chunk = Self::new(chunk_data.x, chunk_data.z, generator);
 
         proto_chunk.light = chunk_data.light_engine.lock().unwrap().clone();
+        proto_chunk.blending_data = chunk_data.blending_data.clone();
 
         let section_data = &chunk_data.section;
         let heightmap_data = chunk_data.heightmap.lock().unwrap();
@@ -663,7 +671,8 @@ impl ProtoChunk {
             ActiveSupplier::Nether(s) => s,
             ActiveSupplier::Overworld(s) => s,
         };
-        let biome_supplier = Blender::NO_BLEND.get_biome_supplier(base_supplier);
+        let blender = Blender::empty();
+        let biome_supplier = blender.get_biome_supplier(base_supplier);
         let min_y = self.bottom_y();
         let bottom_section = section_coords::block_to_section(min_y as i32);
         let top_section = section_coords::block_to_section(min_y as i32 + self.height() as i32 - 1);
@@ -1135,9 +1144,7 @@ impl ProtoChunk {
             }
 
             let mut candidates = set.structures.to_vec();
-            let mut random: RandomGenerator =
+            let carver_seed = get_carver_seed(seed, self.x, self.z);
-                RandomGenerator::Xoroshiro(Xoroshiro::from_seed(seed));
-            let carver_seed = get_carver_seed(&mut random, seed, self.x, self.z);
             let mut random: RandomGenerator =
                 RandomGenerator::Xoroshiro(Xoroshiro::from_seed(carver_seed));
 
@@ -1219,7 +1226,8 @@ impl ProtoChunk {
             ActiveSupplier::Nether(s) => s,
             ActiveSupplier::Overworld(s) => s,
         };
-        let biome_supplier = Blender::NO_BLEND.get_biome_supplier(base_supplier);
+        let blender = Blender::empty();
+        let biome_supplier = blender.get_biome_supplier(base_supplier);
         // Use an empty offset sampler since we are querying arbitrary world coordinates
         let multi_noise_config = MultiNoiseSamplerBuilderOptions::new(0, 0, 0);
         let mut multi_noise_sampler =

pumpkin-world/src/generation/structure/placement.rs

@@ -213,8 +213,7 @@ fn should_generate_frequency(
             random.next_f32() < frequency
         }
         FrequencyReductionMethod::LegacyType3 => {
-            let mut random = RandomGenerator::Xoroshiro(Xoroshiro::from_seed(seed as u64));
+            let carver_seed = get_carver_seed(seed as u64, chunk_x, chunk_z);
-            let carver_seed = get_carver_seed(&mut random, seed as u64, chunk_x, chunk_z);
             let mut random = RandomGenerator::Xoroshiro(Xoroshiro::from_seed(carver_seed));
             random.next_f64() < f64::from(frequency)
         }

pumpkin-world/src/generation/structure/structures/mod.rs

@@ -578,8 +578,7 @@ pub struct StructureGeneratorContext {
 
 #[must_use]
 pub fn create_chunk_random(seed: i64, chunk_x: i32, chunk_z: i32) -> RandomGenerator {
-    let mut random: RandomGenerator = RandomGenerator::Xoroshiro(Xoroshiro::from_seed(seed as u64));
+    let carver_seed = get_carver_seed(seed as u64, chunk_x, chunk_z);
-    let carver_seed = get_carver_seed(&mut random, seed as u64, chunk_x, chunk_z);
     RandomGenerator::Xoroshiro(Xoroshiro::from_seed(carver_seed))
 }