128 lines
3.6 KiB
Rust
128 lines
3.6 KiB
Rust
// SPDX-License-Identifier: AGPL-3.0-only
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//! Core data structures representing the voxel world.
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use bytemuck::{Pod, Zeroable};
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use serde::{Deserialize, Serialize};
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/// The size of a chunk along one axis in blocks.
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pub const CHUNK_SIZE: usize = 32;
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/// The total number of blocks within a single chunk.
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pub const CHUNK_VOLUME: usize = CHUNK_SIZE * CHUNK_SIZE * CHUNK_SIZE;
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/// A unique identifier representing a type of block in the world.
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#[repr(transparent)]
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#[derive(
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Copy,
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Clone,
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Debug,
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Default,
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PartialEq,
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Eq,
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PartialOrd,
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Ord,
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Hash,
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Serialize,
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Deserialize,
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Pod,
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Zeroable,
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)]
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pub struct BlockId(pub u16);
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impl BlockId {
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/// The block identifier representing empty space.
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pub const AIR: BlockId = BlockId(0);
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}
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/// A spatial volume containing voxel data.
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#[derive(Clone, Debug, Serialize, Deserialize)]
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pub struct Chunk {
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/// The array of blocks contained within the chunk.
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pub blocks: Box<[BlockId]>,
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}
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impl Chunk {
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/// Calculates the one-dimensional index for a three-dimensional block coordinate.
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#[inline]
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#[must_use]
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pub const fn index(x: usize, y: usize, z: usize) -> usize {
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(x * CHUNK_SIZE * CHUNK_SIZE) + (z * CHUNK_SIZE) + y
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}
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/// Retrieves the block identifier at the specified coordinates.
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#[must_use]
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pub fn get(&self, x: usize, y: usize, z: usize) -> BlockId {
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self.blocks[Self::index(x, y, z)]
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}
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/// Sets the block identifier at the specified coordinates.
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pub fn set(&mut self, x: usize, y: usize, z: usize, block: BlockId) {
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self.blocks[Self::index(x, y, z)] = block;
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}
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}
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impl Default for Chunk {
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fn default() -> Self {
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Self {
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blocks: vec![BlockId::AIR; CHUNK_VOLUME].into_boxed_slice(),
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}
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}
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}
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/// The three-dimensional spatial coordinates of a chunk in the world.
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#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, Serialize, Deserialize)]
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pub struct ChunkPos {
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/// The X coordinate of the chunk.
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pub x: i32,
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/// The Y coordinate of the chunk.
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pub y: i32,
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/// The Z coordinate of the chunk.
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pub z: i32,
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}
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impl ChunkPos {
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/// Initializes a new chunk position.
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#[must_use]
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pub fn new(x: i32, y: i32, z: i32) -> Self {
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Self { x, y, z }
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}
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/// Initializes a new chunk position from a world-space position measured in blocks.
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#[must_use]
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#[expect(clippy::cast_possible_truncation, clippy::cast_possible_wrap)]
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pub fn from_world(x: f64, y: f64, z: f64) -> Self {
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ChunkPos {
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x: (x.floor() as i32).div_euclid(CHUNK_SIZE as i32),
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y: (y.floor() as i32).div_euclid(CHUNK_SIZE as i32),
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z: (z.floor() as i32).div_euclid(CHUNK_SIZE as i32),
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}
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}
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}
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#[cfg(test)]
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mod tests {
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use super::ChunkPos;
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#[test]
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fn from_world_maps_positive_positions() {
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// A block at 40 falls in chunk 1 (chunk 1 spans blocks 32..=63).
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assert_eq!(ChunkPos::from_world(40.0, 0.0, 0.0).x, 1);
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// The last block of chunk 0 (block 31) stays in chunk 0.
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assert_eq!(ChunkPos::from_world(31.0, 0.0, 0.0).x, 0);
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}
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#[test]
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fn from_world_floors_negative_positions() {
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// Block -1 belongs to chunk -1, not chunk 0: this is the div_euclid contract.
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assert_eq!(ChunkPos::from_world(-1.0, 0.0, 0.0).x, -1);
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// Block -33 belongs to chunk -2 (chunk -2 spans blocks -64..=-33).
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assert_eq!(ChunkPos::from_world(-33.0, 0.0, 0.0).x, -2);
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}
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#[test]
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fn from_world_floors_fractional_positions() {
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// A position of -0.5 lies inside block -1, which is in chunk -1.
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assert_eq!(ChunkPos::from_world(-0.5, 0.0, 0.0).x, -1);
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}
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}
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