Model every text-display metadata field against the Java wire codec

Add a native Java oracle for the actual Display/TextDisplay accessors and encoded metadata, with 513 combinations of flags, opacity, billboard mode and transforms. Preserve styled text and partial updates.

Co-Authored-By: Codex (gpt-6.1-sol) <[email protected]>

crates/horizon-client/examples/probe/main.rs

@@ -85,6 +85,7 @@ mod sprint_probe;
 mod subtitle_fixture;
 mod tab_list_fixture;
 mod team_rules_fixture;
+mod text_display_fixture;
 mod toggle_keys_probe;
 mod tooltip_display_fixture;
 mod trading_fixture;
@@ -170,6 +171,7 @@ probes! {
     team_rules_fixture,
     toggle_keys_probe,
     tooltip_display_fixture,
+    text_display_fixture,
     trading_fixture,
     translucency_fixture,
     weather_fixture,

crates/horizon-client/examples/probe/text_display_fixture.rs

@@ -0,0 +1,28 @@
+use horizon_client::text_display::TextDisplayData;
+use horizon_protocol::{ids, packets::play::Clientbound};
+use std::{error::Error, io::Write};
+
+pub fn main() -> Result<(), Box<dyn Error>> {
+    let args: Vec<String> = crate::args().collect();
+    let mut out = std::fs::File::create(&args[2])?;
+    for line in std::fs::read_to_string(&args[1])?.lines() {
+        let input: serde_json::Value = serde_json::from_str(line)?;
+        let hex = input["wire"].as_str().unwrap();
+        let bytes: Vec<u8> = (0..hex.len())
+            .step_by(2)
+            .map(|i| u8::from_str_radix(&hex[i..i + 2], 16))
+            .collect::<Result<_, _>>()?;
+        let Clientbound::SetEntityData(packet) =
+            Clientbound::decode(ids::play::clientbound::SET_ENTITY_DATA, &bytes)?
+        else {
+            unreachable!()
+        };
+        let mut display = TextDisplayData::default();
+        display.apply(&packet.values);
+        let mut state = serde_json::to_value(&display)?;
+        state["text"] = display.text.plain().into();
+        state["alignment"] = display.alignment().into();
+        writeln!(out, "{}", state)?;
+    }
+    Ok(())
+}

crates/horizon-client/src/lib.rs

@@ -177,6 +177,7 @@ pub mod tab_list;
 pub mod telemetry;
 pub mod testgen;
 pub mod text;
+pub mod text_display;
 pub mod tick_chunk_membership;
 pub mod ticket_levels;
 pub mod title;

crates/horizon-client/src/text_display.rs

@@ -0,0 +1,111 @@
+//! Display/TextDisplay synced data (26.3), checked against vanilla accessors
+//! and ClientboundSetEntityDataPacket's own stream codec.
+use crate::text::Text;
+use horizon_protocol::entity_data::Value;
+use serde::Serialize;
+
+#[derive(Clone, Debug, Serialize)]
+pub struct TextDisplayData {
+    pub interpolation_delay: i32,
+    pub interpolation_duration: i32,
+    pub teleport_duration: i32,
+    pub translation: [f32; 3],
+    pub scale: [f32; 3],
+    pub left_rotation: [f32; 4],
+    pub right_rotation: [f32; 4],
+    pub billboard: u8,
+    pub brightness: i32,
+    pub view_range: f32,
+    pub shadow_radius: f32,
+    pub shadow_strength: f32,
+    pub width: f32,
+    pub height: f32,
+    pub glow_color: i32,
+    #[serde(skip)]
+    pub text: Text,
+    pub line_width: i32,
+    pub background: i32,
+    pub opacity: i8,
+    pub flags: u8,
+}
+
+impl Default for TextDisplayData {
+    fn default() -> Self {
+        Self {
+            interpolation_delay: 0,
+            interpolation_duration: 0,
+            teleport_duration: 0,
+            translation: [0.0; 3],
+            scale: [1.0; 3],
+            left_rotation: [0.0, 0.0, 0.0, 1.0],
+            right_rotation: [0.0, 0.0, 0.0, 1.0],
+            billboard: 0,
+            brightness: -1,
+            view_range: 1.0,
+            shadow_radius: 0.0,
+            shadow_strength: 1.0,
+            width: 0.0,
+            height: 0.0,
+            glow_color: -1,
+            text: Text::empty(),
+            line_width: 200,
+            background: 0x4000_0000,
+            opacity: -1,
+            flags: 0,
+        }
+    }
+}
+
+impl TextDisplayData {
+    /// Omitted fields retain their previous values.
+    pub fn apply(&mut self, values: &[(u8, i32, Value)]) {
+        for (id, _, value) in values {
+            match (id, value) {
+                (8, Value::Int(v)) => self.interpolation_delay = *v,
+                (9, Value::Int(v)) => self.interpolation_duration = *v,
+                (10, Value::Int(v)) => self.teleport_duration = *v,
+                (11, Value::Floats(v)) if v.len() == 3 => self.translation.copy_from_slice(v),
+                (12, Value::Floats(v)) if v.len() == 3 => self.scale.copy_from_slice(v),
+                (13, Value::Floats(v)) if v.len() == 4 => self.left_rotation.copy_from_slice(v),
+                (14, Value::Floats(v)) if v.len() == 4 => self.right_rotation.copy_from_slice(v),
+                (15, Value::Byte(v)) => self.billboard = *v as u8,
+                (16, Value::Int(v)) => self.brightness = *v,
+                (17, Value::Float(v)) => self.view_range = *v,
+                (18, Value::Float(v)) => self.shadow_radius = *v,
+                (19, Value::Float(v)) => self.shadow_strength = *v,
+                (20, Value::Float(v)) => self.width = *v,
+                (21, Value::Float(v)) => self.height = *v,
+                (22, Value::Int(v)) => self.glow_color = *v,
+                (23, Value::Text(v)) => self.text = crate::entity_nbt::name_text(v),
+                (24, Value::Int(v)) => self.line_width = *v,
+                (25, Value::Int(v)) => self.background = *v,
+                (26, Value::Byte(v)) => self.opacity = *v,
+                (27, Value::Byte(v)) => self.flags = *v as u8,
+                _ => {}
+            }
+        }
+    }
+    pub fn alignment(&self) -> &'static str {
+        if self.flags & 8 != 0 {
+            "LEFT"
+        } else if self.flags & 16 != 0 {
+            "RIGHT"
+        } else {
+            "CENTER"
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn partial_updates_retain_values_and_bad_vectors_do_not_panic() {
+        let mut d = TextDisplayData::default();
+        d.apply(&[(24, 1, Value::Int(80)), (27, 0, Value::Byte(24))]);
+        d.apply(&[(11, 0, Value::Floats(vec![1.0]))]);
+        assert_eq!(d.line_width, 80);
+        assert_eq!(d.alignment(), "LEFT");
+        assert_eq!(d.translation, [0.0; 3]);
+    }
+}

mods/horizon/src/test/java/dev/horizonlab/parity/VanillaTextDisplayOracle.java

@@ -0,0 +1,76 @@
+package dev.horizonlab.parity;
+
+import com.google.gson.*;
+import io.netty.buffer.Unpooled;
+import java.nio.file.*;
+import java.lang.reflect.*;
+import java.util.*;
+import net.minecraft.nbt.TagParser;
+import net.minecraft.network.RegistryFriendlyByteBuf;
+import net.minecraft.network.chat.*;
+import net.minecraft.network.protocol.game.ClientboundSetEntityDataPacket;
+import net.minecraft.network.syncher.EntityDataAccessor;
+import net.minecraft.world.entity.*;
+import org.joml.*;
+
+/** Actual accessors/defaults and wire bytes, not a second implementation of their layout. */
+public final class VanillaTextDisplayOracle {
+    static final class Level extends net.minecraft.server.level.ServerLevel {
+        Level() { super(null, null, null, null, null, null, false, 0L, List.of(), false); }
+        @Override public int getNextEntityId() { return 7; }
+        @Override public net.minecraft.core.RegistryAccess registryAccess() { return ParityData.access; }
+    }
+    static final String[] KEYS = {"interpolation_delay", "interpolation_duration", "teleport_duration",
+        "translation", "scale", "left_rotation", "right_rotation", "billboard", "brightness", "view_range",
+        "shadow_radius", "shadow_strength", "width", "height", "glow_color", "text", "line_width", "background", "opacity", "flags"};
+    static final String[] FIELDS = {"DATA_TRANSFORMATION_INTERPOLATION_START_DELTA_TICKS_ID", "DATA_TRANSFORMATION_INTERPOLATION_DURATION_ID", "DATA_POS_ROT_INTERPOLATION_DURATION_ID",
+        "DATA_TRANSLATION_ID", "DATA_SCALE_ID", "DATA_LEFT_ROTATION_ID", "DATA_RIGHT_ROTATION_ID", "DATA_BILLBOARD_RENDER_CONSTRAINTS_ID", "DATA_BRIGHTNESS_OVERRIDE_ID", "DATA_VIEW_RANGE_ID",
+        "DATA_SHADOW_RADIUS_ID", "DATA_SHADOW_STRENGTH_ID", "DATA_WIDTH_ID", "DATA_HEIGHT_ID", "DATA_GLOW_COLOR_OVERRIDE_ID", "DATA_TEXT_ID", "DATA_LINE_WIDTH_ID", "DATA_BACKGROUND_COLOR_ID", "DATA_TEXT_OPACITY_ID", "DATA_STYLE_FLAGS_ID"};
+    static final Gson GSON = new Gson();
+
+    @SuppressWarnings({"rawtypes", "unchecked"})
+    public static void main(String[] args) throws Exception {
+        ParityData.init();
+        var unsafeField = Class.forName("sun.misc.Unsafe").getDeclaredField("theUnsafe");
+        unsafeField.setAccessible(true);
+        Object unsafe = unsafeField.get(null);
+        var level = (Level) unsafe.getClass().getMethod("allocateInstance", Class.class).invoke(unsafe, Level.class);
+        var out = new ArrayList<String>();
+        for (String line : Files.readAllLines(Path.of(args[0]))) {
+            JsonObject input = JsonParser.parseString(line).getAsJsonObject();
+            var type = net.minecraft.core.registries.BuiltInRegistries.ENTITY_TYPE.getValue(net.minecraft.resources.Identifier.parse("minecraft:text_display"));
+            var display = new Display.TextDisplay(type, level);
+            var state = new JsonObject();
+            for (int i = 0; i < KEYS.length; i++) {
+                Field field = (i < 15 ? Display.class : Display.TextDisplay.class).getDeclaredField(FIELDS[i]);
+                field.setAccessible(true);
+                EntityDataAccessor accessor = (EntityDataAccessor) field.get(null);
+                Object value = display.getEntityData().get(accessor);
+                if (input.has(KEYS[i])) {
+                    JsonElement in = input.get(KEYS[i]);
+                    if (value instanceof Integer) value = in.getAsInt();
+                    else if (value instanceof Float) value = in.getAsFloat();
+                    else if (value instanceof Byte) value = in.getAsByte();
+                    else if (value instanceof Vector3f) value = new Vector3f(in.getAsJsonArray().get(0).getAsFloat(), in.getAsJsonArray().get(1).getAsFloat(), in.getAsJsonArray().get(2).getAsFloat());
+                    else if (value instanceof Quaternionf) value = new Quaternionf(in.getAsJsonArray().get(0).getAsFloat(), in.getAsJsonArray().get(1).getAsFloat(), in.getAsJsonArray().get(2).getAsFloat(), in.getAsJsonArray().get(3).getAsFloat());
+                    else if (value instanceof Component) value = ComponentSerialization.CODEC.parse(ParityData.ops, TagParser.parseCompoundFully("{v:" + in + "}").get("v")).getOrThrow();
+                    display.getEntityData().set(accessor, value);
+                }
+                JsonElement encoded;
+                if (value instanceof Vector3f v) encoded = GSON.toJsonTree(new float[]{v.x, v.y, v.z});
+                else if (value instanceof Quaternionf q) encoded = GSON.toJsonTree(new float[]{q.x, q.y, q.z, q.w});
+                else if (value instanceof Component c) encoded = new JsonPrimitive(c.getString());
+                else encoded = GSON.toJsonTree(value);
+                state.add(KEYS[i], encoded);
+            }
+            state.addProperty("alignment", Display.TextDisplay.getAlign(state.get("flags").getAsByte()).name());
+            var values = display.getEntityData().getNonDefaultValues();
+            var buf = new RegistryFriendlyByteBuf(Unpooled.buffer(), ParityData.access);
+            ClientboundSetEntityDataPacket.STREAM_CODEC.encode(buf, new ClientboundSetEntityDataPacket(7, values == null ? List.of() : values));
+            byte[] bytes = new byte[buf.readableBytes()]; buf.readBytes(bytes); buf.release();
+            var result = new JsonObject(); result.add("expected", state); result.addProperty("wire", HexFormat.of().formatHex(bytes));
+            out.add(GSON.toJson(result));
+        }
+        Files.write(Path.of(args[1]), out);
+    }
+}

tools/test_text_display_parity.py

@@ -0,0 +1,56 @@
+#!/usr/bin/env python3
+"""Decode text-display metadata produced by vanilla's actual entity accessors/codecs."""
+import json
+import os
+from pathlib import Path
+try:
+    from . import lab, test_rust_parity as base, oracle_harness as harness
+except ImportError:
+    import lab
+    import test_rust_parity as base
+    import oracle_harness as harness
+
+
+def main():
+    build = lab.LOCAL / 'text-display-parity'
+    build.mkdir(parents=True, exist_ok=True)
+    (build / 'report.json').unlink(missing_ok=True)
+    lock, jars, libraries = base.verify_artifacts()
+    cases = [{}] + [dict(flags=flags, opacity=opacity, billboard=billboard,
+        text={'text': 'Lobby 日本語', 'bold': bool(flags & 1)},
+        translation=[1.25, -2.5, 0.0], scale=[0.5, 2.0, 1.0],
+        left_rotation=[0, 0, 0, 1], right_rotation=[0, 1, 0, 0],
+        line_width=80, background=-2147418368, brightness=15728880,
+        interpolation_delay=-1, interpolation_duration=12, teleport_duration=4,
+        view_range=2.0, shadow_radius=0.5, shadow_strength=0.75, width=3.0, height=2.0, glow_color=16711680)
+        for flags in range(32) for opacity in (-128, -1, 0, 127) for billboard in range(4)]
+    fixtures = build / 'cases.jsonl'
+    fixtures.write_text(''.join(json.dumps(c, ensure_ascii=False) + '\n' for c in cases))
+    classes = build / 'classes'
+    classes.mkdir(exist_ok=True)
+    source = lab.ROOT / 'mods/horizon/src/test/java/dev/horizonlab/parity/VanillaTextDisplayOracle.java'
+    sources = [Path(__file__).resolve(), source,
+        lab.ROOT / 'crates/horizon-client/src/text_display.rs',
+        lab.ROOT / 'crates/horizon-protocol/src/entity_data.rs', lab.ROOT / 'Cargo.lock']
+    tested = base.source_hashes(sources)
+    cp = os.pathsep.join(map(str, [jars['server'], *libraries]))
+    run = lambda command, name: harness.run_logged(command, build, name)
+    run(['javac', '--release', lock['minecraft']['java_major'], '-proc:none', '-sourcepath',
+         lab.ROOT / 'mods/horizon/src/test/java', '-cp', cp, '-d', classes, source], 'compile-java')
+    run(['java', '-Xmx1G', '-cp', str(classes) + os.pathsep + cp,
+         'dev.horizonlab.parity.VanillaTextDisplayOracle', fixtures, build / 'java.jsonl'], 'java')
+    command = harness.build_probe(build, 'text_display_fixture')
+    run([*command, build / 'java.jsonl', build / 'rust.jsonl'], 'rust')
+    expected = [json.loads(line)['expected'] for line in (build / 'java.jsonl').read_text().splitlines()]
+    actual = [json.loads(line) for line in (build / 'rust.jsonl').read_text().splitlines()]
+    assert len(expected) == len(actual) == len(cases)
+    for index, (a, b) in enumerate(zip(expected, actual)):
+        assert a == b, (index, a, b)
+    base.ensure_sources_unchanged(sources, tested)
+    lab.write_json(build / 'report.json', {'minecraft': lab.VERSION, 'cases': len(cases), 'pass': True,
+        'sources_sha256': tested, 'java_output_sha256': lab.digest(build / 'java.jsonl', 'sha256')})
+    print(f'Text display metadata parity: {len(cases)} cases match vanilla')
+
+
+if __name__ == '__main__':
+    main()