From 4782e6eb3038e34d559e3f56b74a6acedf58edf3 Mon Sep 17 00:00:00 2001
From: Bixilon <bixilon@bixilon.de>
Date: Thu, 1 Jun 2023 00:16:45 +0200
Subject: [PATCH] chunk queue comparator

This reduces meshing overhead and sorting time minimal
---
 .../world/queue/meshing/ChunkMeshingQueue.kt  | 17 ++------
 .../queue/meshing/ChunkQueueComparator.kt     | 43 +++++++++++++++++++
 2 files changed, 47 insertions(+), 13 deletions(-)
 create mode 100644 src/main/java/de/bixilon/minosoft/gui/rendering/world/queue/meshing/ChunkQueueComparator.kt

diff --git a/src/main/java/de/bixilon/minosoft/gui/rendering/world/queue/meshing/ChunkMeshingQueue.kt b/src/main/java/de/bixilon/minosoft/gui/rendering/world/queue/meshing/ChunkMeshingQueue.kt
index d20c4cf7b..00a2ca59c 100644
--- a/src/main/java/de/bixilon/minosoft/gui/rendering/world/queue/meshing/ChunkMeshingQueue.kt
+++ b/src/main/java/de/bixilon/minosoft/gui/rendering/world/queue/meshing/ChunkMeshingQueue.kt
@@ -1,6 +1,6 @@
 /*
  * Minosoft
- * Copyright (C) 2020-2022 Moritz Zwerger
+ * Copyright (C) 2020-2023 Moritz Zwerger
  *
  * This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
  *
@@ -13,13 +13,11 @@
 
 package de.bixilon.minosoft.gui.rendering.world.queue.meshing
 
-import de.bixilon.kotlinglm.vec3.Vec3i
 import de.bixilon.kutil.cast.CastUtil.unsafeCast
 import de.bixilon.kutil.concurrent.lock.simple.SimpleLock
 import de.bixilon.kutil.concurrent.pool.ThreadPool
 import de.bixilon.kutil.concurrent.pool.ThreadPoolRunnable
 import de.bixilon.minosoft.data.world.positions.ChunkPosition
-import de.bixilon.minosoft.gui.rendering.util.vec.vec3.Vec3iUtil.length2
 import de.bixilon.minosoft.gui.rendering.world.WorldQueueItem
 import de.bixilon.minosoft.gui.rendering.world.WorldRenderer
 import de.bixilon.minosoft.gui.rendering.world.queue.QueuePosition
@@ -30,6 +28,7 @@ import de.bixilon.minosoft.util.SystemInformation
 class ChunkMeshingQueue(
     private val renderer: WorldRenderer,
 ) {
+    private val comparator = ChunkQueueComparator()
     val tasks = MeshPrepareTaskManager(renderer)
     val maxMeshesToLoad = if (SystemInformation.RUNTIME.maxMemory() > 1_000_000_000) 150 else 80
 
@@ -46,16 +45,8 @@ class ChunkMeshingQueue(
 
     fun sort() {
         lock()
-        val position = renderer.cameraChunkPosition
-        val height = renderer.cameraSectionHeight
-        val cameraSectionPosition = Vec3i(position.x, height, position.y)
-        queue.sortBy {
-            if (it.chunkPosition == position) {
-                // our own chunk always has the highest priority
-                return@sortBy -Int.MAX_VALUE
-            }
-            (it.sectionPosition - cameraSectionPosition).length2()
-        }
+        comparator.update(renderer)
+        queue.sortWith(comparator)
         unlock()
     }
 
diff --git a/src/main/java/de/bixilon/minosoft/gui/rendering/world/queue/meshing/ChunkQueueComparator.kt b/src/main/java/de/bixilon/minosoft/gui/rendering/world/queue/meshing/ChunkQueueComparator.kt
new file mode 100644
index 000000000..335a882bc
--- /dev/null
+++ b/src/main/java/de/bixilon/minosoft/gui/rendering/world/queue/meshing/ChunkQueueComparator.kt
@@ -0,0 +1,43 @@
+/*
+ * Minosoft
+ * Copyright (C) 2020-2023 Moritz Zwerger
+ *
+ * This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with this program. If not, see <https://www.gnu.org/licenses/>.
+ *
+ * This software is not affiliated with Mojang AB, the original developer of Minecraft.
+ */
+
+package de.bixilon.minosoft.gui.rendering.world.queue.meshing
+
+import de.bixilon.kotlinglm.vec2.Vec2i
+import de.bixilon.minosoft.data.world.positions.ChunkPosition
+import de.bixilon.minosoft.gui.rendering.util.vec.vec2.Vec2iUtil.EMPTY
+import de.bixilon.minosoft.gui.rendering.world.WorldQueueItem
+import de.bixilon.minosoft.gui.rendering.world.WorldRenderer
+
+class ChunkQueueComparator : Comparator<WorldQueueItem> {
+    private var position: ChunkPosition = Vec2i.EMPTY
+    private var height = 0
+
+
+    fun update(renderer: WorldRenderer) {
+        this.position = renderer.cameraChunkPosition
+        this.height = renderer.cameraSectionHeight
+    }
+
+    private fun compare(item: WorldQueueItem): Int {
+        val array = item.sectionPosition.array
+        val x = array[0] - position.x
+        val y = array[1] - height
+        val z = array[2] - position.y
+        return (x * x + y * y + z * z)
+    }
+
+    override fun compare(a: WorldQueueItem, b: WorldQueueItem): Int {
+        return compare(a).compareTo(compare(b))
+    }
+}