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Spigot still maintains some partial implementation of "tick skipping", a practice in which the MinecraftServer.currentTick field is updated not by an increment of one per actual tick, but instead set to System.currentTimeMillis() / 50. This behaviour means that the tracked tick may "skip" a tick value in case a previous tick took more than the expected 50ms. To compensate for this in important paths, spigot/craftbukkit implements "wall-time". Instead of incrementing/decrementing ticks on block entities/entities by one for each call to their tick() method, they instead increment/decrement important values, like an ItemEntity's age or pickupDelay, by the difference of `currentTick - lastTick`, where `lastTick` is the value of `currentTick` during the last tick() call. These "fixes" however do not play nicely with minecraft's simulation distance as entities/block entities implementing the above behaviour would "catch up" their values when moving from a non-ticking chunk to a ticking one as their `lastTick` value remains stuck on the last tick in a ticking chunk and hence lead to a large "catch up" once ticked again. Paper completely removes the "tick skipping" behaviour (See patch "Further-improve-server-tick-loop"), making the above precautions completely unnecessary, which also rids paper of the previous described incompatibility with non-ticking chunks.
29 lines
1.6 KiB
Diff
29 lines
1.6 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: David Slovikosky <davidslovikosky@gmail.com>
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Date: Tue, 9 Jun 2020 00:10:03 -0700
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Subject: [PATCH] Fix missing chunks due to integer overflow
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This patch fixes a bug in the EndIslandDensityFunction class where the distance
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from 0,0 squared overflows the maximum size of an integer. The overflow leads
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to hard chunk borders around 370,000 blocks from 0,0. After this cutoff there
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is a few hundred thousand block gap before end land resuming to generate at
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530,000 blocks from spawn. This is due to the integer flipping back and forth.
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The fix for the issue is quite simple, casting chunk coordinates to longs
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allows the distance calculation to avoid overflow and work as intended.
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This issue is being tracked in Mojira ticket MC-159283
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diff --git a/src/main/java/net/minecraft/world/level/levelgen/DensityFunctions.java b/src/main/java/net/minecraft/world/level/levelgen/DensityFunctions.java
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index 6171d57a0e5d1aecadfb2c23a72a92d897ca41ee..b09bc1dac649ce9f4826edc1923c843804226993 100644
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--- a/src/main/java/net/minecraft/world/level/levelgen/DensityFunctions.java
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+++ b/src/main/java/net/minecraft/world/level/levelgen/DensityFunctions.java
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@@ -521,7 +521,7 @@ public final class DensityFunctions {
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int j = z / 2;
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int k = x % 2;
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int l = z % 2;
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- float f = 100.0F - Mth.sqrt((float)(x * x + z * z)) * 8.0F;
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+ float f = 100.0F - Mth.sqrt((long) x * (long) x + (long) z * (long) z) * 8.0F; // Paper - cast ints to long to avoid integer overflow
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f = Mth.clamp(f, -100.0F, 80.0F);
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for (int m = -12; m <= 12; m++) {
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