acdream/tests/AcDream.App.Tests/Rendering/Issue120ReciprocalPingPongTests.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Numerics;
using AcDream.App.Rendering;
using DatReaderWriter;
using DatReaderWriter.Options;
using Xunit;
using Xunit.Abstractions;
using DatLandBlockInfo = DatReaderWriter.DBObjs.LandBlockInfo;

namespace AcDream.App.Tests.Rendering;

/// <summary>
/// #120 reproduction (2026-06-11): the armed tripwire self-attributed on the
/// re-gate launch (regate-118-119-launch.log) — a pure TWO-CELL reciprocal
/// ping-pong, 64 laps each: `chain root=0xA9B4015C eye=(109.995,37.158,96.249)
/// cells: 0xA9B40162x64 0xA9B4015Cx64` and `root=0xA9B3010F
/// eye=(175.771,-107.310,118.814) cells: 0xA9B30103x64 0xA9B3010Fx64`.
///
/// Mechanism: with the eye within PortalSideEpsilon (±1 cm — the T2-refuted-
/// to-tighten root-lag tolerance; retail's is 0.0002) of the portal plane,
/// the in-plane case counts as interior for BOTH cells, so views flow
/// A→B→A…; each lap re-clips through two near-edge-on apertures whose
/// intersection numerics wobble by more than CellView's 1e-3 dedup grid →
/// every lap keys as a NEW polygon → 128-deep in-place recursion. The prior
/// convergence sweeps (CornerFloodReplayTests) could not reproduce because
/// they only load the corner building 0x016F-0x0175 — both firing pairs are
/// OUTSIDE that set.
///
/// The fix class is the handoff's own prediction ("dedup admitting
/// near-duplicates per lap"): a round-trip re-emission is, in exact math, a
/// SUBSET of the region that originated it — CellView.Add must reject
/// contained polygons, which makes union growth strictly area-increasing and
/// the flood convergent regardless of clip-numerics drift.
/// </summary>
public class Issue120ReciprocalPingPongTests
{
    private readonly ITestOutputHelper _out;
    public Issue120ReciprocalPingPongTests(ITestOutputHelper output) => _out = output;

    internal static Dictionary<uint, LoadedCell> LoadAllInteriorCells(DatCollection dats, uint landblock)
    {
        var lbi = dats.Get<DatLandBlockInfo>(landblock | 0xFFFEu);
        Assert.NotNull(lbi);
        var cells = new Dictionary<uint, LoadedCell>();
        for (uint low = 0x0100u; low < 0x0100u + lbi!.NumCells; low++)
        {
            uint id = landblock | low;
            try { cells[id] = CornerFloodReplayTests.LoadCell(dats, id); }
            catch (InvalidOperationException) { /* sparse cell ids — skip */ }
        }
        return cells;
    }

    private static Matrix4x4 ViewProjFor(Vector3 eye, Vector3 lookAt)
    {
        var view = Matrix4x4.CreateLookAt(eye, lookAt, Vector3.UnitZ);
        var proj = Matrix4x4.CreatePerspectiveFieldOfView(1.2f, 1280f / 720f, 0.1f, 5000f);
        return view * proj;
    }

    public static readonly TheoryData<uint, uint, uint, float, float, float> CapturedSites = new()
    {
        // landblock, cellA (root at firing), cellB, eye x, y, z — straight from the chain dumps
        { 0xA9B40000u, 0x015Cu, 0x0162u, 109.995f, 37.158f, 96.249f },
        { 0xA9B30000u, 0x010Fu, 0x0103u, 175.771f, -107.310f, 118.814f },
    };

    /// <summary>
    /// The captured firing sites, swept over orientations (the dump has no view
    /// matrix) and over both cells as root. Invariants: the tripwire stays 0
    /// AND no CellView accumulates a pathological polygon pile (the duplicate
    /// build-up is the defect even below the depth-128 failsafe).
    /// </summary>
    [Theory]
    [MemberData(nameof(CapturedSites))]
    public void CapturedPingPongSites_Converge(uint landblock, uint lowA, uint lowB, float ex, float ey, float ez)
    {
        var datDir = CornerFloodReplayTests.ResolveDatDir();
        if (datDir is null) { _out.WriteLine("SKIP: dats unavailable"); return; }

        using var dats = new DatCollection(datDir, DatAccessType.Read);
        var cells = LoadAllInteriorCells(dats, landblock);
        Func<uint, LoadedCell?> lookup = id => cells.TryGetValue(id, out var c) ? c : null;

        Assert.True(cells.ContainsKey(landblock | lowA), $"cell 0x{landblock | lowA:X8} not loaded");
        Assert.True(cells.ContainsKey(landblock | lowB), $"cell 0x{landblock | lowB:X8} not loaded");

        var eye = new Vector3(ex, ey, ez);
        var roots = new[] { cells[landblock | lowA], cells[landblock | lowB] };

        PortalVisibilityBuilder.ConvergenceTripwireCount = 0;
        var failures = new List<string>();
        int builds = 0, maxPolys = 0;

        foreach (var root in roots)
        {
            for (int yaw = 0; yaw < 8; yaw++)
            {
                float a = yaw * MathF.PI / 4f;
                foreach (float pitch in new[] { -0.4f, 0f, 0.4f })
                {
                    var dir = Vector3.Normalize(new Vector3(MathF.Cos(a), MathF.Sin(a), pitch));
                    int before = PortalVisibilityBuilder.ConvergenceTripwireCount;
                    var frame = PortalVisibilityBuilder.Build(root, eye, lookup, ViewProjFor(eye, eye + dir * 3f));
                    builds++;
                    int after = PortalVisibilityBuilder.ConvergenceTripwireCount;

                    int polys = frame.CellViews.Count == 0 ? 0 : frame.CellViews.Values.Max(v => v.Polygons.Count);
                    if (polys > maxPolys) maxPolys = polys;

                    if (after != before || polys > 32)
                        failures.Add(FormattableString.Invariant(
                            $"root=0x{root.CellId:X8} yaw={yaw} pitch={pitch} tripwire={after - before} maxCellPolys={polys}"));
                }
            }
        }

        _out.WriteLine($"builds={builds} maxCellPolys={maxPolys} failures={failures.Count}");
        foreach (var f in failures) _out.WriteLine($"  {f}");
        Assert.True(failures.Count == 0,
            $"{failures.Count}/{builds} builds broke convergence at the captured #120 site (see output)");
    }

    /// <summary>
    /// The geometric trigger, driven directly: eye swept through the
    /// both-sides-pass window (±PortalSideEpsilon = ±1 cm) of the reciprocal
    /// portal plane between the two captured cells, looking across and along
    /// the aperture. Same convergence invariants.
    /// </summary>
    [Theory]
    [MemberData(nameof(CapturedSites))]
    public void PortalPlaneWindow_BothSidesPass_Converges(uint landblock, uint lowA, uint lowB, float ex, float ey, float ez)
    {
        _ = ex; _ = ey; _ = ez; // geometric variant derives its own eyes
        var datDir = CornerFloodReplayTests.ResolveDatDir();
        if (datDir is null) { _out.WriteLine("SKIP: dats unavailable"); return; }

        using var dats = new DatCollection(datDir, DatAccessType.Read);
        var cells = LoadAllInteriorCells(dats, landblock);
        Func<uint, LoadedCell?> lookup = id => cells.TryGetValue(id, out var c) ? c : null;

        var cellA = cells[landblock | lowA];
        uint cellBId = landblock | lowB;

        // the portal from A to B (the ping-pong pair)
        int portalIdx = -1;
        for (int i = 0; i < cellA.Portals.Count; i++)
            if (cellA.Portals[i].OtherCellId == (ushort)lowB) { portalIdx = i; break; }
        Assert.True(portalIdx >= 0, $"no portal 0x{lowA:X4}->0x{lowB:X4}");
        var poly = cellA.PortalPolygons[portalIdx];
        Assert.True(poly is { Length: >= 3 }, "portal polygon degenerate");

        var centroidLocal = Vector3.Zero;
        foreach (var v in poly!) centroidLocal += v;
        centroidLocal /= poly.Length;
        var centroidWorld = Vector3.Transform(centroidLocal, cellA.WorldTransform);
        var plane = cellA.ClipPlanes[portalIdx];
        var normalWorld = Vector3.Normalize(Vector3.TransformNormal(plane.Normal, cellA.WorldTransform));

        PortalVisibilityBuilder.ConvergenceTripwireCount = 0;
        var failures = new List<string>();
        int builds = 0, maxPolys = 0;

        foreach (float off in new[] { -0.009f, -0.004f, 0f, 0.004f, 0.009f })
        {
            var eye = centroidWorld + normalWorld * off;
            foreach (var root in new[] { cellA, cells[cellBId] })
            {
                for (int yaw = 0; yaw < 8; yaw++)
                {
                    float a = yaw * MathF.PI / 4f;
                    var dir = Vector3.Normalize(new Vector3(MathF.Cos(a), MathF.Sin(a), 0.1f));
                    int before = PortalVisibilityBuilder.ConvergenceTripwireCount;
                    var frame = PortalVisibilityBuilder.Build(root, eye, lookup, ViewProjFor(eye, eye + dir * 3f));
                    builds++;
                    int after = PortalVisibilityBuilder.ConvergenceTripwireCount;

                    int polys = frame.CellViews.Count == 0 ? 0 : frame.CellViews.Values.Max(v => v.Polygons.Count);
                    if (polys > maxPolys) maxPolys = polys;

                    if (after != before || polys > 32)
                        failures.Add(FormattableString.Invariant(
                            $"off={off:F3} root=0x{root.CellId:X8} yaw={yaw} tripwire={after - before} maxCellPolys={polys}"));
                }
            }
        }

        _out.WriteLine($"builds={builds} maxCellPolys={maxPolys} failures={failures.Count}");
        foreach (var f in failures) _out.WriteLine($"  {f}");
        Assert.True(failures.Count == 0,
            $"{failures.Count}/{builds} builds broke convergence in the ±ε portal-plane window (see output)");
    }
}