From 217ec33413290858a07dd267ebd1a93b695094c5 Mon Sep 17 00:00:00 2001
From: Thinkofname <thinkofdeath@spigotmc.org>
Date: Mon, 21 Mar 2016 16:51:19 +0000
Subject: [PATCH] Render chunks nearest to the player first

---
 src/chunk_builder.rs | 34 ++++++++++++++++++++++++++++++++--
 src/main.rs          |  2 +-
 src/world/mod.rs     | 18 +++++++++++++-----
 3 files changed, 46 insertions(+), 8 deletions(-)

diff --git a/src/chunk_builder.rs b/src/chunk_builder.rs
index 130206e..a4e18e2 100644
--- a/src/chunk_builder.rs
+++ b/src/chunk_builder.rs
@@ -13,6 +13,9 @@ pub struct ChunkBuilder {
     threads: Vec<(mpsc::Sender<BuildReq>, thread::JoinHandle<()>)>,
     free_builders: Vec<usize>,
     built_recv: mpsc::Receiver<(usize, BuildReply)>,
+
+    sections: Vec<(i32, i32, i32)>,
+    next_collection: f64,
 }
 
 impl ChunkBuilder {
@@ -32,6 +35,8 @@ impl ChunkBuilder {
             threads: threads,
             free_builders: free,
             built_recv: built_recv,
+            sections: vec![],
+            next_collection: 0.0,
         }
     }
 
@@ -42,7 +47,8 @@ impl ChunkBuilder {
         }
     }
 
-    pub fn tick(&mut self, world: &mut world::World, renderer: &mut render::Renderer) {
+    pub fn tick(&mut self, world: &mut world::World, renderer: &mut render::Renderer, delta: f64) {
+        use std::cmp::Ordering;
         while let Ok((id, val)) = self.built_recv.try_recv() {
             world.reset_building_flag(val.position);
 
@@ -53,8 +59,32 @@ impl ChunkBuilder {
         if self.free_builders.is_empty() {
             return;
         }
-        while let Some((x, y, z)) = world.next_dirty_chunk_section() {
+        self.next_collection -= delta;
+        if self.next_collection <= 0.0 {
+            let mut sections = world.get_dirty_chunk_sections();
+            sections.sort_by(|a, b| {
+                let xx = ((a.0<<4)+8) as f64 - renderer.camera.pos.x;
+                let yy = ((a.1<<4)+8) as f64 - renderer.camera.pos.y;
+                let zz = ((a.2<<4)+8) as f64 - renderer.camera.pos.z;
+                let a_dist = xx*xx + yy*yy + zz*zz;
+                let xx = ((b.0<<4)+8) as f64 - renderer.camera.pos.x;
+                let yy = ((b.1<<4)+8) as f64 - renderer.camera.pos.y;
+                let zz = ((b.2<<4)+8) as f64 - renderer.camera.pos.z;
+                let b_dist = xx*xx + yy*yy + zz*zz;
+                if a_dist == b_dist {
+                    Ordering::Equal
+                } else if a_dist > b_dist {
+                    Ordering::Less
+                } else {
+                    Ordering::Greater
+                }
+            });
+            self.sections = sections;
+            self.next_collection = 60.0;
+        }
+        while let Some((x, y, z)) = self.sections.pop() {
             let t_id = self.free_builders.pop().unwrap();
+            world.set_building_flag((x, y, z));
             let (cx, cy, cz) = (x << 4, y << 4, z << 4);
             let mut snapshot = world.capture_snapshot(cx - 2, cy - 2, cz - 2, 20, 20, 20);
             snapshot.make_relative(-2, -2, -2);
diff --git a/src/main.rs b/src/main.rs
index 11d1bd0..0790817 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -210,7 +210,7 @@ fn main() {
         game.tick(delta);
         game.server.tick(&mut game.renderer, delta);
 
-        game.chunk_builder.tick(&mut game.server.world, &mut game.renderer);
+        game.chunk_builder.tick(&mut game.server.world, &mut game.renderer, delta);
 
         game.screen_sys.tick(delta, &mut game.renderer, &mut ui_container);
         game.console
diff --git a/src/world/mod.rs b/src/world/mod.rs
index 078dc35..96653e3 100644
--- a/src/world/mod.rs
+++ b/src/world/mod.rs
@@ -47,19 +47,27 @@ impl World {
         }
     }
 
-    pub fn next_dirty_chunk_section(&mut self) -> Option<(i32, i32, i32)> {
+    pub fn get_dirty_chunk_sections(&mut self) -> Vec<(i32, i32, i32)> {
+        let mut out = vec![];
         for (_, chunk) in &mut self.chunks {
             for sec in &mut chunk.sections {
                 if let Some(sec) = sec.as_mut() {
                     if !sec.building && sec.dirty {
-                        sec.building = true;
-                        sec.dirty = false;
-                        return Some((chunk.position.0, sec.y as i32, chunk.position.1));
+                        out.push((chunk.position.0, sec.y as i32, chunk.position.1));
                     }
                 }
             }
         }
-        None
+        out
+    }
+
+    pub fn set_building_flag(&mut self, pos: (i32, i32, i32)) {
+        if let Some(chunk) = self.chunks.get_mut(&CPos(pos.0, pos.2)) {
+            if let Some(sec) = chunk.sections[pos.1 as usize].as_mut() {
+                sec.building = true;
+                sec.dirty = false;
+            }
+        }
     }
 
     pub fn reset_building_flag(&mut self, pos: (i32, i32, i32)) {