From 15eec53d50094dbcd904921a90d48696fa319989 Mon Sep 17 00:00:00 2001
From: Evert Prants <imsonotsleepy@gmail.com>
Date: Sat, 3 Aug 2019 13:56:31 +0300
Subject: [PATCH] a lil improvement

---
 src/index.js | 41 ++++++++++++++++++++++++++++++-----------
 1 file changed, 30 insertions(+), 11 deletions(-)

diff --git a/src/index.js b/src/index.js
index 8711cc6..faa36fe 100644
--- a/src/index.js
+++ b/src/index.js
@@ -138,6 +138,11 @@ class Chunk {
 class ChunkWorld {
   constructor () {
     this.chunks = []
+    this.dirty = true
+  }
+
+  mkdirty () {
+    this.dirty = true
   }
 
   static generateTerrain (c) {
@@ -181,13 +186,15 @@ class ChunkWorld {
   }
 
   update (pos, scale) {
+    if (!this.dirty) return
     let positions = ChunkWorld.getPositionsInViewport(pos, scale)
+    let generated = false
     for (let p in positions) {
       let cpos = positions[p]
       let found = false
       for (let i in this.chunks) {
         let chunk = this.chunks[i]
-        if (chunk.x == cpos.x && chunk.y == cpos.y) {
+        if (chunk.x === cpos.x && chunk.y === cpos.y) {
           found = true
           break
         }
@@ -195,25 +202,33 @@ class ChunkWorld {
 
       if (!found) {
         let chunk = new Chunk(cpos.x, cpos.y)
+        generated = true
         ChunkWorld.generateTerrain(chunk)
         this.chunks.push(chunk)
         break
       }
     }
+
+    // We generated nothing this time around, mark it as not dirty
+    if (!generated) {
+      this.dirty = false
+    }
   }
 
   render (r, o, s) {
+    let scaledSize = TotalSize / s
+
+    // Convert to chunk-space coordinates
+    let localX = Math.floor(cursor.x / scaledSize) * -1
+    let localY = Math.floor(cursor.y / scaledSize) * -1
+    let localW = Math.ceil(canvas.width / scaledSize) + 1
+    let localH = Math.ceil(canvas.height / scaledSize)
+
     for (let i in this.chunks) {
       let chunk = this.chunks[i]
-      let scaledSize = TotalSize / s
-      // Convert to chunk-space coordinates
-      let localX = Math.floor(cursor.x / scaledSize) * -1
-      let localY = Math.floor(cursor.y / scaledSize) * -1
-      let aw = Math.ceil(canvas.width / scaledSize) + 1
-      let ah = Math.ceil(canvas.height / scaledSize)
 
-      if (chunk.x <= localX + aw && chunk.x + 1 >= localX &&
-        chunk.y <= localY + ah && chunk.y + 1 >= localY) {
+      if (chunk.x <= localX + localW && chunk.x + 1 >= localX &&
+        chunk.y <= localY + localH && chunk.y + 1 >= localY) {
         Chunk.render(r, chunk, o, s)
       }
     }
@@ -222,7 +237,7 @@ class ChunkWorld {
 
 let world = new ChunkWorld()
 let input = new Input(canvas)
-let noise = new BetterNoise(1, /*amplitude = */15, /*persistence = */0.4, /*octaves = */5, /*period = */120, /*lacunarity = */2)
+let noise = new BetterNoise(1, /* amplitude = */15, /* persistence = */0.4, /* octaves = */5, /* period = */120, /* lacunarity = */2)
 let zoom = 2
 
 let tiles = [
@@ -232,7 +247,7 @@ let tiles = [
   new Tile('stone', '#515151')
 ]
 
-let cursor = {x: 0, y: 0}
+let cursor = { x: 0, y: 0 }
 
 function render () {
   ctx.fillStyle = '#00aaff'
@@ -243,14 +258,18 @@ function render () {
 function update (dt) {
   if (input.isDown('w')) {
     cursor.y += 6
+    world.mkdirty()
   } else if (input.isDown('s')) {
     cursor.y -= 6
+    world.mkdirty()
   }
 
   if (input.isDown('a')) {
     cursor.x += 6
+    world.mkdirty()
   } else if (input.isDown('d')) {
     cursor.x -= 6
+    world.mkdirty()
   }
 
   world.update(cursor, zoom)