acdream/tests/AcDream.Core.Tests/World/LandblockLoaderTests.cs

using System.Numerics;
using AcDream.Core.World;
using DatReaderWriter.DBObjs;
using DatReaderWriter.Types;

namespace AcDream.Core.Tests.World;

public class LandblockLoaderTests
{
    private static LandBlock BuildFlatLandBlock()
    {
        var block = new LandBlock
        {
            HasObjects = true,
            Terrain = new TerrainInfo[81],
            Height = new byte[81],
        };
        for (int i = 0; i < 81; i++)
        {
            block.Terrain[i] = (ushort)0;
            block.Height[i] = 0;
        }
        return block;
    }

    [Fact]
    public void BuildEntitiesFromInfo_StabsAndBuildings_AreMappedToEntities()
    {
        var info = new LandBlockInfo
        {
            Objects =
            {
                new Stab
                {
                    Id = 0x01000042u,  // GfxObj id
                    Frame = new Frame
                    {
                        Origin = new Vector3(10, 20, 5),
                        Orientation = Quaternion.Identity,
                    },
                },
                new Stab
                {
                    Id = 0x02000099u,  // Setup id
                    Frame = new Frame
                    {
                        Origin = new Vector3(30, 40, 10),
                        Orientation = Quaternion.Identity,
                    },
                },
            },
            Buildings =
            {
                new BuildingInfo
                {
                    ModelId = 0x020000AAu,  // Setup for a building
                    Frame = new Frame
                    {
                        Origin = new Vector3(50, 60, 0),
                        Orientation = Quaternion.Identity,
                    },
                },
            },
        };

        var entities = LandblockLoader.BuildEntitiesFromInfo(info);

        Assert.Equal(3, entities.Count);
        Assert.Contains(entities, e => e.SourceGfxObjOrSetupId == 0x01000042u && e.Position == new Vector3(10, 20, 5));
        Assert.Contains(entities, e => e.SourceGfxObjOrSetupId == 0x02000099u && e.Position == new Vector3(30, 40, 10));
        Assert.Contains(entities, e => e.SourceGfxObjOrSetupId == 0x020000AAu && e.Position == new Vector3(50, 60, 0));
    }

    [Fact]
    public void BuildEntitiesFromInfo_AssignsMonotonicIds()
    {
        var info = new LandBlockInfo
        {
            Objects =
            {
                new Stab { Id = 0x01000001u, Frame = new Frame() },
                new Stab { Id = 0x01000002u, Frame = new Frame() },
                new Stab { Id = 0x01000003u, Frame = new Frame() },
            },
        };

        var entities = LandblockLoader.BuildEntitiesFromInfo(info);

        var ids = entities.Select(e => e.Id).OrderBy(i => i).ToArray();
        Assert.Equal(3, ids.Distinct().Count());  // all unique
    }

    [Fact]
    public void BuildEntitiesFromInfo_UnsupportedIdType_IsSkipped()
    {
        // 0x03xxxxxx is neither GfxObj (0x01) nor Setup (0x02).
        var info = new LandBlockInfo
        {
            Objects =
            {
                new Stab { Id = 0x01000001u, Frame = new Frame() },
                new Stab { Id = 0x03000002u, Frame = new Frame() },  // skipped
                new Stab { Id = 0x02000003u, Frame = new Frame() },
            },
        };

        var entities = LandblockLoader.BuildEntitiesFromInfo(info);

        Assert.Equal(2, entities.Count);
        Assert.DoesNotContain(entities, e => e.SourceGfxObjOrSetupId == 0x03000002u);
    }

    [Fact]
    public void BuildEntitiesFromInfo_Empty_ReturnsEmpty()
    {
        var entities = LandblockLoader.BuildEntitiesFromInfo(new LandBlockInfo());
        Assert.Empty(entities);
    }

    [Fact]
    public void BuildBuildingTerrainCells_UsesBuildingsOnlyAndMapsToMeshCellIndex()
    {
        var info = new LandBlockInfo
        {
            Objects =
            {
                new Stab
                {
                    Id = 0x02000001u,
                    Frame = new Frame { Origin = new Vector3(120, 72, 0) },
                },
            },
            Buildings =
            {
                new BuildingInfo
                {
                    ModelId = 0x020000AAu,
                    Frame = new Frame { Origin = new Vector3(141.5f, 7.2f, 94f) },
                },
            },
        };

        var cells = LandblockLoader.BuildBuildingTerrainCells(info);

        Assert.Single(cells);
        Assert.Contains(5, cells); // cy=0, cx=5 => mesh index cy * 8 + cx.
    }

    [Fact]
    public void BuildEntitiesFromInfo_WithLandblockId_NamespacesIdsForGlobalUniqueness()
    {
        // Regression: cross-LB stab Id collision was the cause of visual
        // glitches in Tier 1 cache (commit <THIS_COMMIT>) — buildings rendered
        // up in the air with wrong textures because cache was keyed by
        // entity.Id and stab Ids restarted at 1 per landblock.
        var info = new LandBlockInfo
        {
            Objects =
            {
                new Stab { Id = 0x01000001u, Frame = new Frame() },
                new Stab { Id = 0x01000002u, Frame = new Frame() },
            },
        };

        var entitiesLbA = LandblockLoader.BuildEntitiesFromInfo(info, landblockId: 0xA9B40000u);
        var entitiesLbB = LandblockLoader.BuildEntitiesFromInfo(info, landblockId: 0xA9B50000u);

        // No two entities across LB A and LB B share the same Id.
        var idsA = entitiesLbA.Select(e => e.Id).ToArray();
        var idsB = entitiesLbB.Select(e => e.Id).ToArray();
        Assert.Empty(idsA.Intersect(idsB));

        // The namespace top byte is 0xC0 for stabs (distinct from 0x80 scenery,
        // 0x40 interior, low-range live entities).
        Assert.All(idsA, id => Assert.Equal(0xC0u, (id >> 24) & 0xFFu));
        Assert.All(idsB, id => Assert.Equal(0xC0u, (id >> 24) & 0xFFu));
    }

    [Fact]
    public void BuildEntitiesFromInfo_LegacyZeroLandblockId_StartsAtOne()
    {
        // Backward compat: existing callers (tests pre-fix) call without a
        // landblockId and get the legacy "starts at 1" behavior.
        var info = new LandBlockInfo
        {
            Objects = { new Stab { Id = 0x01000001u, Frame = new Frame() } },
        };

        var entities = LandblockLoader.BuildEntitiesFromInfo(info);

        Assert.Single(entities);
        Assert.Equal(1u, entities[0].Id);
    }
}