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// Voxel-chunk schema.
use crate::ecs::PayloadLocator;
use crate::ecs::asset_id::AssetId;
use alloc::vec::Vec;
/// A voxel grid that compiles into a single mesh.
///
/// A dense grid of blocks compiled into a single mesh at build time. Use one
/// chunk per region of a voxel/Minecraft-style world; reference it from a
/// [Prop](#prop)'s `mesh` field. Hidden faces between two solid blocks are
/// dropped, so a fully filled chunk contributes zero triangles to its interior.
///
/// The palette must contain at least one entry whose [BlockType](#blocktype) has
/// `solid: false` (typically named `air`); cells whose palette entry is
/// non-solid emit no faces. Faces are only emitted between a solid block and
/// either an empty neighbour or the outside of the chunk.
#[derive(Debug, Clone, serde::Serialize, serde::Deserialize)]
#[serde(default)]
pub struct VoxelChunk {
/// Asset identity; injected via `inject_name`. Not part of `args`.
#[serde(skip)]
pub asset_id: AssetId,
/// [BlockType](#blocktype) asset names. `blocks[i]` is an index into this list.
pub palette: Vec<AssetId>,
/// Chunk dimensions `[dx, dy, dz]` in blocks.
pub dim: [u32; 3],
/// World units per block edge.
pub block_size: f32,
/// Flat block array, length `dx*dy*dz`. Index = `x + y*dx + z*dx*dy`.
pub blocks: Vec<u32>,
/// Number of level-of-detail versions to generate, including the original.
/// `1` (the default) generates none.
pub lod_levels: u32,
/// Camera distances at which to switch to each lower-detail version; empty
/// lets the build choose defaults.
#[serde(default)]
pub lod_distances: Vec<f32>,
/// Injected at load time from the compiled blob payload.
#[serde(skip)]
pub locator: Option<PayloadLocator>,
}
impl Default for VoxelChunk {
fn default() -> Self {
Self {
asset_id: AssetId::default(),
palette: Vec::new(),
dim: [0, 0, 0],
block_size: 1.0,
blocks: Vec::new(),
lod_levels: 1,
lod_distances: Vec::new(),
locator: None,
}
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn a_blank_chunk_is_empty_with_metre_sized_blocks() {
let c = VoxelChunk::default();
assert_eq!(c.dim, [0, 0, 0]);
assert_eq!(c.block_size, 1.0);
assert!(c.blocks.is_empty());
assert!(c.palette.is_empty());
assert_eq!(c.lod_levels, 1);
assert!(c.lod_distances.is_empty());
assert!(c.locator.is_none());
}
#[test]
fn an_authored_chunk_parses_and_round_trips_through_postcard() {
crate::test_support::install_resolvers();
let c: VoxelChunk = serde_json::from_str(
r#"{"palette":["air","stone"],"dim":[2,1,2],"block_size":0.5,
"blocks":[0,1,1,0],"lod_levels":2,"lod_distances":[16]}"#,
)
.unwrap();
assert_eq!(c.palette, [AssetId(3), AssetId(5)]);
// The block list indexes the palette, one entry per cell in `dim`.
assert_eq!(c.blocks.len() as u32, c.dim[0] * c.dim[1] * c.dim[2]);
let bytes = postcard::to_allocvec(&c).unwrap();
let back: VoxelChunk = postcard::from_bytes(&bytes).unwrap();
assert_eq!(back.dim, [2, 1, 2]);
assert_eq!(back.block_size, 0.5);
assert_eq!(back.blocks, [0, 1, 1, 0]);
assert_eq!(back.lod_levels, 2);
assert_eq!(back.lod_distances, [16.0]);
assert_eq!(back.asset_id, AssetId::default());
}
}