From f14674ee9ae2e7a27f142d66d66a21d3aba4459a Mon Sep 17 00:00:00 2001
From: Joshua Barretto <joshua.s.barretto@gmail.com>
Date: Sat, 3 Aug 2019 22:11:31 +0100
Subject: [PATCH] Switched to UnitChooser

---
 world/src/block/natural.rs     | 17 +++--------------
 world/src/column/mod.rs        |  6 ++++--
 world/src/util/mod.rs          |  2 ++
 world/src/util/unit_chooser.rs | 34 ++++++++++++++++++++++++++++++++++
 4 files changed, 43 insertions(+), 16 deletions(-)
 create mode 100644 world/src/util/unit_chooser.rs

diff --git a/world/src/block/natural.rs b/world/src/block/natural.rs
index 1ecac53823..557015a92c 100644
--- a/world/src/block/natural.rs
+++ b/world/src/block/natural.rs
@@ -2,7 +2,7 @@ use super::{BlockGen, StructureInfo, StructureMeta, ZCache};
 use crate::{
     all::ForestKind,
     column::{ColumnGen, ColumnSample},
-    util::{HashCache, RandomPerm, Sampler},
+    util::{HashCache, RandomPerm, Sampler, UnitChooser},
     CONFIG,
 };
 use common::{assets, terrain::Structure};
@@ -11,7 +11,7 @@ use std::sync::Arc;
 use vek::*;
 
 static VOLUME_RAND: RandomPerm = RandomPerm::new(0xDB21C052);
-static UNIT_RAND: RandomPerm = RandomPerm::new(0x700F4EC7);
+static UNIT_CHOOSER: UnitChooser = UnitChooser::new(0x700F4EC7);
 static QUIRKY_RAND: RandomPerm = RandomPerm::new(0xA634460F);
 
 pub fn structure_gen<'a>(
@@ -61,22 +61,11 @@ pub fn structure_gen<'a>(
         }
     };
 
-    const UNIT_CHOICES: [(Vec2<i32>, Vec2<i32>); 8] = [
-        (Vec2 { x: 1, y: 0 }, Vec2 { x: 0, y: 1 }),
-        (Vec2 { x: 1, y: 0 }, Vec2 { x: 0, y: -1 }),
-        (Vec2 { x: -1, y: 0 }, Vec2 { x: 0, y: 1 }),
-        (Vec2 { x: -1, y: 0 }, Vec2 { x: 0, y: -1 }),
-        (Vec2 { x: 0, y: 1 }, Vec2 { x: 1, y: 0 }),
-        (Vec2 { x: 0, y: 1 }, Vec2 { x: -1, y: 0 }),
-        (Vec2 { x: 0, y: -1 }, Vec2 { x: 1, y: 0 }),
-        (Vec2 { x: 0, y: -1 }, Vec2 { x: -1, y: 0 }),
-    ];
-
     Some(StructureInfo {
         pos: st_pos3d,
         seed: st_seed,
         meta: StructureMeta::Volume {
-            units: UNIT_CHOICES[UNIT_RAND.get(st_seed) as usize % UNIT_CHOICES.len()],
+            units: UNIT_CHOOSER.get(st_seed),
             volume: &volumes[(VOLUME_RAND.get(st_seed) / 13) as usize % volumes.len()],
         },
     })
diff --git a/world/src/column/mod.rs b/world/src/column/mod.rs
index 02114eddde..443739b17d 100644
--- a/world/src/column/mod.rs
+++ b/world/src/column/mod.rs
@@ -2,7 +2,7 @@ use crate::{
     all::ForestKind,
     block::StructureMeta,
     sim::{LocationInfo, SimChunk},
-    util::Sampler,
+    util::{Sampler, UnitChooser},
     World, CONFIG,
 };
 use common::{
@@ -23,6 +23,8 @@ pub struct ColumnGen<'a> {
     world: &'a World,
 }
 
+static UNIT_CHOOSER: UnitChooser = UnitChooser::new(0x700F4EC7);
+
 lazy_static! {
     pub static ref DUNGEONS: Vec<Arc<Structure>> = vec![
         // green oaks
@@ -65,7 +67,7 @@ impl<'a> ColumnGen<'a> {
                 pos,
                 seed,
                 meta: Some(StructureMeta::Volume {
-                    units: (Vec2::unit_x(), Vec2::unit_y()),
+                    units: UNIT_CHOOSER.get(seed),
                     volume: &DUNGEONS[0],
                 }),
             })
diff --git a/world/src/util/mod.rs b/world/src/util/mod.rs
index fd538e21ce..a8a71d0c03 100644
--- a/world/src/util/mod.rs
+++ b/world/src/util/mod.rs
@@ -2,6 +2,7 @@ pub mod hash_cache;
 pub mod random;
 pub mod sampler;
 pub mod structure;
+pub mod unit_chooser;
 
 // Reexports
 pub use self::{
@@ -9,4 +10,5 @@ pub use self::{
     random::{RandomField, RandomPerm},
     sampler::{Sampler, SamplerMut},
     structure::StructureGen2d,
+    unit_chooser::UnitChooser,
 };
diff --git a/world/src/util/unit_chooser.rs b/world/src/util/unit_chooser.rs
new file mode 100644
index 0000000000..c5c0203090
--- /dev/null
+++ b/world/src/util/unit_chooser.rs
@@ -0,0 +1,34 @@
+use super::{RandomPerm, Sampler};
+use vek::*;
+
+const UNIT_CHOICES: [(Vec2<i32>, Vec2<i32>); 8] = [
+    (Vec2 { x: 1, y: 0 }, Vec2 { x: 0, y: 1 }),
+    (Vec2 { x: 1, y: 0 }, Vec2 { x: 0, y: -1 }),
+    (Vec2 { x: -1, y: 0 }, Vec2 { x: 0, y: 1 }),
+    (Vec2 { x: -1, y: 0 }, Vec2 { x: 0, y: -1 }),
+    (Vec2 { x: 0, y: 1 }, Vec2 { x: 1, y: 0 }),
+    (Vec2 { x: 0, y: 1 }, Vec2 { x: -1, y: 0 }),
+    (Vec2 { x: 0, y: -1 }, Vec2 { x: 1, y: 0 }),
+    (Vec2 { x: 0, y: -1 }, Vec2 { x: -1, y: 0 }),
+];
+
+pub struct UnitChooser {
+    perm: RandomPerm,
+}
+
+impl UnitChooser {
+    pub const fn new(seed: u32) -> Self {
+        Self {
+            perm: RandomPerm::new(seed),
+        }
+    }
+}
+
+impl Sampler for UnitChooser {
+    type Index = u32;
+    type Sample = (Vec2<i32>, Vec2<i32>);
+
+    fn get(&self, perm: Self::Index) -> Self::Sample {
+        UNIT_CHOICES[self.perm.get(perm) as usize % UNIT_CHOICES.len()]
+    }
+}