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    <title>Mojang Studios Jira</title>
    <link>https://bugs.mojang.com</link>
    <description>This file is an XML representation of an issue</description>
    <language>en</language>    <build-info>
        <version>9.12.2</version>
        <build-number>9120002</build-number>
        <build-date>10-01-2024</build-date>
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<item>
            <title>[MCPE-21020] Effects don&apos;t wrap around into the negatives at 128</title>
                <link>https://bugs.mojang.com/browse/MCPE-21020</link>
                <project id="10200" key="MCPE">Minecraft (Bedrock codebase)</project>
                    <description>&lt;ul&gt;
	&lt;li&gt;In the java version , using commands to get an effect with the amplifier between 128 and 255 makes it negative. This is very useful as it&apos;s the only way to reduce jump height. However , I tried to make a command block which makes you unable to jump via jump_boost 50 128 But there is no wrap around into the negatives on pocket edition. Instead , it makes you jump even higher than the maximum jump height of 127 in Java.Please fix this bug so i can be able to make a command block which makes you unable to jump. Also it&apos;s 1.0.5 but I can&apos;t figure out how to set the version affected to 1.0.5 so I did 1.0.5.54 because it&apos;s the closest thing I could figure out how to do.&lt;/li&gt;
&lt;/ul&gt;
</description>
            <key id="167416">MCPE-21020</key>
            <summary>Effects don&apos;t wrap around into the negatives at 128</summary>
                <type id="1" iconUrl="https://bugs.mojang.com/secure/viewavatar?size=xsmall&amp;avatarId=18903&amp;avatarType=issuetype">Bug</type>
                                    <status id="5" iconUrl="https://bugs.mojang.com/images/icons/statuses/resolved.png" description="A resolution has been taken, and it is awaiting verification by reporter. From here issues are either reopened, or are closed.">Resolved</status>
                    <statusCategory id="3" key="done" colorName="success"/>
                                    <resolution id="5">Cannot Reproduce</resolution>
                                            <reporter username="5tr4">Anomonous Anomonous</reporter>
                        <labels>
                    </labels>
                <created>Fri, 7 Apr 2017 01:10:49 +0200</created>
                <updated>Wed, 11 Apr 2018 20:26:43 +0200</updated>
                            <resolved>Wed, 11 Apr 2018 20:26:42 +0200</resolved>
                                    <version>1.0.5.54</version>
                                                                        <votes>0</votes>
                                    <watches>3</watches>
                                                                            <comments>
                            <comment id="446235" author="mega_spud" created="Wed, 11 Apr 2018 20:26:42 +0200"  >&lt;p&gt;Cleaning up old tickets:  This ticket has not been updated recently (1 year+) so is being closed as &lt;em&gt;Cannot Reproduce&lt;/em&gt;.  If you feel this is still a valid issue then please comment, or create a new ticket following the &lt;a href=&quot;http://help.mojang.com/customer/portal/articles/801354-writing-helpful-bug-reports-for-minecraft&quot; title=&quot;How To Write helpful bug reports&quot; class=&quot;external-link&quot; target=&quot;_blank&quot; rel=&quot;nofollow noopener&quot;&gt;Issue Guidelines&lt;/a&gt;.&lt;/p&gt;

&lt;p&gt;&lt;b&gt;Quick Links&lt;/b&gt;:&lt;br/&gt;
&#128211; &lt;a href=&quot;http://help.mojang.com/customer/portal/articles/801354-writing-helpful-bug-reports-for-minecraft&quot; title=&quot;How To Write Awesome Tickets! &#128175;&quot; class=&quot;external-link&quot; target=&quot;_blank&quot; rel=&quot;nofollow noopener&quot;&gt;Issue Guidelines&lt;/a&gt; &amp;#8211; &#128172; &lt;a href=&quot;https://www.reddit.com/r/MCPE/&quot; title=&quot;Help From the Minecraft Community &#128377;&quot; class=&quot;external-link&quot; target=&quot;_blank&quot; rel=&quot;nofollow noopener&quot;&gt;Community Support&lt;/a&gt; &amp;#8211; &#128231; &lt;a href=&quot;https://feedback.minecraft.net/&quot; title=&quot;Feedback and Suggestions &#9997;&#65039;&quot; class=&quot;external-link&quot; target=&quot;_blank&quot; rel=&quot;nofollow noopener&quot;&gt;Feedback&lt;/a&gt; &amp;#8211; &#128214; &lt;a href=&quot;http://minecraft.gamepedia.com/Minecraft_Wiki&quot; title=&quot;Official Minecraft Wiki &#127891;&quot; class=&quot;external-link&quot; target=&quot;_blank&quot; rel=&quot;nofollow noopener&quot;&gt;Game Wiki&lt;/a&gt;&lt;/p&gt;</comment>
                            <comment id="377127" author="skylinerw" created="Mon, 10 Apr 2017 11:19:18 +0200"  >&lt;p&gt;Firstly, high amplifiers are not supported in Java edition (&lt;a href=&quot;https://bugs.mojang.com/browse/MC-10755&quot; title=&quot;Effects with amplifiers over 4 (level V)/enchantments with level over max default value are not supported&quot; class=&quot;issue-link&quot; data-issue-key=&quot;MC-10755&quot;&gt;&lt;del&gt;MC-10755&lt;/del&gt;&lt;/a&gt;).&lt;/p&gt;

&lt;p&gt;I&apos;d like to clarify that what happens in Java edition is a client-side desync bug caused by overflow when sending the amplifier to the client (stored on the server as an int, sent to client as a byte). Since the client controls movement and thinks they have a negative amplifier, their jump height is reduced.&lt;/p&gt;

&lt;p&gt;However, the server is expecting them to go extremely high into the air, so when the player takes damage (while jumping), the server resyncs their position and the client then sees themselves high in the air.&lt;/p&gt;

&lt;p&gt;When the player data is saved to NBT, the integer amplifier from the server is typecasted to byte (into the &lt;tt&gt;Amplifier&lt;/tt&gt; tag). When the player logs back in, both the server and client will agree on the amplifier&apos;s value now that it&apos;s within byte range for both and desyncing no longer occurs.&lt;/p&gt;

&lt;p&gt;Except that in 1.11, the &lt;tt&gt;Amplifier&lt;/tt&gt; byte tag will only have its value read as 0 or higher. If it were -4 due to overflow, it will be considered as 0 instead, effectively changing what the effect does when relogging.&lt;/p&gt;

&lt;p&gt;Thus a single command with a 128+ amplifier has three issues in Java edition: client desync, overflow on save, and read differently after relogging.&lt;/p&gt;</comment>
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