damagedBlocks field was changed?

fuzzybat23 · September 17, 2017

Were there any changes to the damagedBlocks field between 1.12 and 1.12.1? This code worked perfectly in 1.12, but I was just notified that it started throwing an error with 1.12.1.

s

package com.fuzzybat23.esbb;

import net.minecraft.client.Minecraft;
import net.minecraft.client.renderer.DestroyBlockProgress;
import net.minecraft.client.renderer.RenderGlobal;
import net.minecraft.util.math.RayTraceResult;
import java.lang.reflect.Field;
import java.util.HashMap;

class GetBlockDamage
{
    static float getBlockDamage(RayTraceResult target)
    {
        try
        {
            Field f;
            try
            {  f = RenderGlobal.class.getDeclaredField("damagedBlocks");  }
             catch (NoSuchFieldException e)
            {  f = RenderGlobal.class.getDeclaredField("damagedBlocks");  }
            f.setAccessible(true);

            HashMap<Integer, DestroyBlockProgress> map = (HashMap<Integer, DestroyBlockProgress>) f.get(Minecraft.getMinecraft().renderGlobal);

            for (DestroyBlockProgress destroyblockprogress : map.values())
            {
                if (destroyblockprogress.getPosition().equals(target.getBlockPos()))
                {
                    if (destroyblockprogress.getPartialBlockDamage() >= 0 && destroyblockprogress.getPartialBlockDamage() <= 10)
                        return destroyblockprogress.getPartialBlockDamage() / 10.0F;
                }
            }
        } catch (Exception e)
        {  e.printStackTrace();  }
        return 0F;
    }
}

[01:31:59] [main/INFO] [STDERR]: [com.fuzzybat23.esbb.GetBlockDamage:getBlockDamage:34]: java.lang.NoSuchFieldException: damagedBlocks

Choonster · September 17, 2017

It doesn't look like there were any changes to the field between 1.12 and 1.12.1.

Which environment did the error occur in? If it was outside of the development environment, it happened because you didn't check for the SRG name of a field (you check the MCP name twice).

You should use Forge's ReflectionHelper class instead of the Class methods when reflecting Vanilla fields/methods as it allows you to supply both the SRG and MCP names of the field/method instead of requiring you to manually check both.

You should also look up the Field/Method object once and store it in a field instead of looking it up every time as this is the slowest part of reflection. I recommend doing this in the initialiser of a private static final field.

Abastro · September 17, 2017

I doubt that it might work out of dev environment with any version. You should specify both the mcp name and srg name to get the field due to MC obfuscation. Use mcpbot to find the field srg name.

Edit: so basically, do what choonster said.. ninja'd =<

Edited September 17, 2017 by Abastro

fuzzybat23 · September 17, 2017

I don't suppose there's a tutorial for this ReflectionHelper Class? I suppose it would go something like this, which would then be changed to add in this ReflectionHelper thing of which I know absolutely nothing about?

package com.fuzzybat23.esbb;
+import ...

class GetBlockDamage
{
	private static final Field f = RenderGlobal.class.getDeclaredField("damagedBlocks");

}

Choonster · September 17, 2017

24 minutes ago, fuzzybat23 said:

I don't suppose there's a tutorial for this ReflectionHelper Class? I suppose it would go something like this, which would then be changed to add in this ReflectionHelper thing of which I know absolutely nothing about?

The only methods you need are ReflectionHelper.findField and ReflectionHelper.findMethod, which replace Class#getDeclaredField and Class#getDeclaredMethod respectively. The parameters of ReflectionHelper.findField are fairly obvious and the parameters of ReflectionHelper.findMethod are documented in its doc comment.

fuzzybat23 · September 17, 2017

But there's no actual page for Reflection Helper in Forgedocs like there should have been from the very start. Something native to forge, but with no helpful documentation within ForgeDocs. I suppose you can see my, and other coder's frustrations when they do that?

fuzzybat23 · September 17, 2017

Well, I did this and it compiled and tested correctly from within IntelliJ, but when I moved the compiled mod to my main mincraft folder to test. it still ends up throwing the same error and fails to access the damagedBlocks field.

This particular field I'm trying to access is within RenderGlobal.class

    private final Map<Integer, DestroyBlockProgress> damagedBlocks = Maps.newHashMap();

class GetBlockDamage
{

    static float getBlockDamage(RayTraceResult target)
    {
        try
        {
            final Field f = ReflectionHelper.findField(RenderGlobal.class, "damagedBlocks");

            f.setAccessible(true);

            HashMap<Integer, DestroyBlockProgress> map = (HashMap<Integer, DestroyBlockProgress>) f.get(Minecraft.getMinecraft().renderGlobal);

            for (DestroyBlockProgress destroyblockprogress : map.values())
            {
                if (destroyblockprogress.getPosition().equals(target.getBlockPos()))
                {
                    if (destroyblockprogress.getPartialBlockDamage() >= 0 && destroyblockprogress.getPartialBlockDamage() <= 10)
                        return destroyblockprogress.getPartialBlockDamage() / 10.0F;
                }
            }
        } catch (Exception e)
        {  e.printStackTrace();  }
        return 0F;
    }
}

06:29:04	game		info	[10:29:04] [main/INFO]: [com.fuzzybat23.esbb.GetBlockDamage:getBlockDamage:43]: net.minecraftforge.fml.relauncher.ReflectionHelper$UnableToFindFieldException: java.lang.NoSuchFieldException: damagedBlocks
06:29:04	game		info	[10:29:04] [main/INFO]: [com.fuzzybat23.esbb.GetBlockDamage:getBlockDamage:43]: 	at net.minecraftforge.fml.relauncher.ReflectionHelper.findField(ReflectionHelper.java:107)
06:29:04	game		info	[10:29:04] [main/INFO]: [com.fuzzybat23.esbb.GetBlockDamage:getBlockDamage:43]: 	at com.fuzzybat23.esbb.GetBlockDamage.getBlockDamage(GetBlockDamage.java:28)
06:29:04	game		info	[10:29:04] [main/INFO]: [com.fuzzybat23.esbb.GetBlockDamage:getBlockDamage:43]: 	at com.fuzzybat23.esbb.ESBB.drawSelectionBox(ESBB.java:192)
06:29:04	game		info	[10:29:04] [main/INFO]: [com.fuzzybat23.esbb.GetBlockDamage:getBlockDamage:43]: 	at com.fuzzybat23.esbb.ESBB.onDrawBlockSelectionBox(ESBB.java:99)
06:29:04	game		info	[10:29:04] [main/INFO]: [com.fuzzybat23.esbb.GetBlockDamage:getBlockDamage:43]: 	at net.minecraftforge.fml.common.eventhandler.ASMEventHandler_29_ESBB_onDrawBlockSelectionBox_DrawBlockHighlightEvent.invoke(.dynamic)
06:29:04	game		info	[10:29:04] [main/INFO]: [com.fuzzybat23.esbb.GetBlockDamage:getBlockDamage:43]: 	at net.minecraftforge.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:90)
06:29:04	game		info	[10:29:04] [main/INFO]: [com.fuzzybat23.esbb.GetBlockDamage:getBlockDamage:43]: 	at net.minecraftforge.fml.common.eventhandler.EventBus.post(EventBus.java:179)
06:29:04	game		info	[10:29:04] [main/INFO]: [com.fuzzybat23.esbb.GetBlockDamage:getBlockDamage:43]: 	at net.minecraftforge.client.ForgeHooksClient.onDrawBlockHighlight(ForgeHooksClient.java:155)
06:29:04	game		info	[10:29:04] [main/INFO]: [com.fuzzybat23.esbb.GetBlockDamage:getBlockDamage:43]: 	at sun.reflect.GeneratedMethodAccessor57.invoke(Unknown Source)
06:29:04	game		info	[10:29:04] [main/INFO]: [com.fuzzybat23.esbb.GetBlockDamage:getBlockDamage:43]: 	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
06:29:04	game		info	[10:29:04] [main/INFO]: [com.fuzzybat23.esbb.GetBlockDamage:getBlockDamage:43]: 	at java.lang.reflect.Method.invoke(Method.java:483)
06:29:04	game		info	[10:29:04] [main/INFO]: [com.fuzzybat23.esbb.GetBlockDamage:getBlockDamage:43]: 	at Reflector.callBoolean(Reflector.java:569)
06:29:04	game		info	[10:29:04] [main/INFO]: [com.fuzzybat23.esbb.GetBlockDamage:getBlockDamage:43]: 	at net.minecraft.client.renderer.EntityRenderer.func_175068_a(EntityRenderer.java:1784)
06:29:04	game		info	[10:29:04] [main/INFO]: [com.fuzzybat23.esbb.GetBlockDamage:getBlockDamage:43]: 	at net.minecraft.client.renderer.EntityRenderer.func_78471_a(EntityRenderer.java:1590)
06:29:04	game		info	[10:29:04] [main/INFO]: [com.fuzzybat23.esbb.GetBlockDamage:getBlockDamage:43]: 	at net.minecraft.client.renderer.EntityRenderer.func_181560_a(EntityRenderer.java:1361)
06:29:04	game		info	[10:29:04] [main/INFO]: [com.fuzzybat23.esbb.GetBlockDamage:getBlockDamage:43]: 	at net.minecraft.client.Minecraft.func_71411_J(Minecraft.java:1117)
06:29:04	game		info	[10:29:04] [main/INFO]: [com.fuzzybat23.esbb.GetBlockDamage:getBlockDamage:43]: 	at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:397)
06:29:04	game		info	[10:29:04] [main/INFO]: [com.fuzzybat23.esbb.GetBlockDamage:getBlockDamage:43]: 	at net.minecraft.client.main.Main.main(SourceFile:123)
06:29:04	game		info	[10:29:04] [main/INFO]: [com.fuzzybat23.esbb.GetBlockDamage:getBlockDamage:43]: 	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
06:29:04	game		info	[10:29:04] [main/INFO]: [com.fuzzybat23.esbb.GetBlockDamage:getBlockDamage:43]: 	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
06:29:04	game		info	[10:29:04] [main/INFO]: [com.fuzzybat23.esbb.GetBlockDamage:getBlockDamage:43]: 	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
06:29:04	game		info	[10:29:04] [main/INFO]: [com.fuzzybat23.esbb.GetBlockDamage:getBlockDamage:43]: 	at java.lang.reflect.Method.invoke(Method.java:483)
06:29:04	game		info	[10:29:04] [main/INFO]: [com.fuzzybat23.esbb.GetBlockDamage:getBlockDamage:43]: 	at net.minecraft.launchwrapper.Launch.launch(Launch.java:135)
06:29:04	game		info	[10:29:04] [main/INFO]: [com.fuzzybat23.esbb.GetBlockDamage:getBlockDamage:43]: 	at net.minecraft.launchwrapper.Launch.main(Launch.java:28)

Choonster · September 17, 2017

45 minutes ago, fuzzybat23 said:

But there's no actual page for Reflection Helper in Forgedocs like there should have been from the very start. Something native to forge, but with no helpful documentation within ForgeDocs. I suppose you can see my, and other coder's frustrations when they do that?

The Forge documentation is community maintained and so far nobody has suggested or written any documentation on reflection.

If you create an issue or PR in the documentation repository, this may be added.

16 minutes ago, fuzzybat23 said:

Well, I did this and it compiled and tested correctly from within IntelliJ, but when I moved the compiled mod to my main mincraft folder to test. it still ends up throwing the same error and fails to access the damagedBlocks field.

You're still only checking the MCP name, you need to supply both the MCP and SRG names for reflection to work inside and outside of the development environment.

Draco18s · September 17, 2017

http://export.mcpbot.bspk.rs/

fuzzybat23 · September 17, 2017

Can you give me a little more to go on besides " you need to supply both the MCP and SRG names " like an actual example of how such a code should look? I say that because I have absolutely no idea how to do such a thing. You can't exactly learn Forge programming in a text book.

Draco18s · September 17, 2017

https://github.com/Draco18s/ReasonableRealism/blob/1.12.1/src/main/java/com/draco18s/hardlib/EasyRegistry.java#L212

Or you could look at the method signature of the method:

public static Method findMethod(@Nonnull Class<?> clazz, @Nonnull String methodName, @Nullable String methodObfName, Class<?>... parameterTypes)

"Method Name"

"Method Obf Name"

Couldn't be more obvious.

Edited September 17, 2017 by Draco18s

fuzzybat23 · September 18, 2017

Kind of helpful but not looking for the method, looking for the field. What you meant to say was, I have to include three arguments with findField, not two. Instead of

final Field f = ReflectionHelper.findField(RenderGlobal.class, "damagedBlocks");

it has to look like this

final Field f = ReflectionHelper.findField(RenderGlobal.class, "damagedBlocks", "field_72738_E");

which is how you supply both mcp and srg names. See, that's how you provide a helpful answer, with examples. So if anyone out there with the same problem as me comes across this post. There it is. An example of how you do it, not just someone saying oh, you have to provide these two things. Still, thanks for your small breadcrumb trail I was able to use to dig through pages after pages on google to find the answer myself. Once again, examples examples examples, because not everyone is as smart as you when it comes to java coding.

And yes, that extra little

,"field_72738_E"

got it working perfectly with no errors.

Edited September 18, 2017 by fuzzybat23

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