Add some world defs

src/game.rs

@@ -0,0 +1,16 @@
+use crate::{math::WorldPos, world::World};
+
+pub struct GameState {
+    transient: TransientGameState,
+    persistent: PersistentGameState,
+}
+
+/// Transient game state, not saved to disk
+pub struct TransientGameState {
+    camera_offset: WorldPos,
+}
+
+/// Persistent game state, saved to disk
+pub struct PersistentGameState {
+    world: World,
+}

src/main.rs

@@ -1,5 +1,8 @@
 mod app;
+mod game;
 mod graphics;
+mod math;
+mod world;
 
 use app::App;
 

src/math.rs

@@ -0,0 +1,6 @@
+pub type WorldPosScalar = i32;
+
+pub struct WorldPos {
+    x: WorldPosScalar,
+    y: WorldPosScalar,
+}

src/world.rs

@@ -0,0 +1,28 @@
+use fnv::FnvHashMap;
+
+type ChunkPosScalar = i16;
+
+#[derive(Hash)]
+struct ChunkPos {
+    x: ChunkPosScalar,
+    y: ChunkPosScalar,
+}
+
+pub struct World {
+    chunks: FnvHashMap<ChunkPos, Chunk>,
+}
+
+const CHUNK_EXTENT: u16 = 256;
+const CHUNK_N_BLOCKS: usize = CHUNK_EXTENT as usize * CHUNK_EXTENT as usize;
+
+type ChunkBlocks = [Block; CHUNK_N_BLOCKS];
+
+pub struct Chunk {
+    blocks: ChunkBlocks,
+}
+
+type BlockId = u16;
+
+pub struct Block {
+    id: BlockId,
+}