acdream/tests/AcDream.Core.Tests/Physics/TerrainSurfaceTests.cs
Erik 16d182c2f0 perf(physics): reuse reset-complete transition scratch
Mirror retail's ten-deep LIFO transition lifetime, retain all query scratch with complete reset contracts, and remove Tier-0 enum boxing without changing collision decisions. Fresh and retained engines are bit-identical across the expanded oracle, while measured transition profiles now allocate 0 bytes per resolve.
2026-07-25 14:37:02 +02:00

218 lines
8.5 KiB
C#

using System.Numerics;
using AcDream.Core.Physics;
using Xunit;
namespace AcDream.Core.Tests.Physics;
public class TerrainSurfaceTests
{
// A height table where index N maps to N * 1.0f (linear).
// Makes test assertions predictable: height byte 10 → Z = 10.0.
private static float[] LinearHeightTable()
{
var table = new float[256];
for (int i = 0; i < 256; i++) table[i] = i * 1.0f;
return table;
}
// A flat heightmap where every vertex is height byte 50.
private static byte[] FlatHeightmap(byte value = 50)
{
var heights = new byte[81];
Array.Fill(heights, value);
return heights;
}
[Fact]
public void SampleZ_FlatTerrain_ReturnsSameValueEverywhere()
{
var surface = new TerrainSurface(FlatHeightmap(50), LinearHeightTable());
Assert.Equal(50f, surface.SampleZ(0f, 0f));
Assert.Equal(50f, surface.SampleZ(96f, 96f));
Assert.Equal(50f, surface.SampleZ(191f, 191f));
}
[Fact]
public void SampleZ_SlopeAlongX_InterpolatesLinearly()
{
// Heights increase along X: column 0 = byte 10, column 8 = byte 90.
// Each column step is (90-10)/8 = 10 bytes.
var heights = new byte[81];
for (int x = 0; x < 9; x++)
for (int y = 0; y < 9; y++)
heights[x * 9 + y] = (byte)(10 + x * 10);
var surface = new TerrainSurface(heights, LinearHeightTable());
// At x=0 (vertex 0): Z = 10
Assert.Equal(10f, surface.SampleZ(0f, 96f), precision: 1);
// At x=96 (midpoint, vertex 4): Z = 50
Assert.Equal(50f, surface.SampleZ(96f, 96f), precision: 1);
// At x=192 (vertex 8): Z = 90
Assert.Equal(90f, surface.SampleZ(192f, 96f), precision: 1);
// At x=48 (between vertex 2 and 3): Z = 30 + 0.5 * 10 = 35
// vertex 2 = byte 30, vertex 3 = byte 40, midpoint = 35
Assert.Equal(35f, surface.SampleZ(60f, 96f), precision: 1);
}
[Fact]
public void SampleZ_ClampsOutOfBounds()
{
var surface = new TerrainSurface(FlatHeightmap(42), LinearHeightTable());
// Negative coordinates clamp to 0
Assert.Equal(42f, surface.SampleZ(-10f, -10f));
// Beyond 192 clamps to boundary
Assert.Equal(42f, surface.SampleZ(300f, 300f));
}
[Fact]
public void SampleZFromHeightmap_AgreesWithInstance_AcrossWholeLandblock()
{
// Issue #48 conformance: the static SampleZFromHeightmap (bilinear
// fallback used at scenery hydration before physics registers a
// landblock) must produce the same Z as the instance SampleZ
// (player physics path) at every (x, y). The previous fallback in
// GameWindow had its diagonal arms swapped — this test pins both
// paths to one source of truth.
//
// Heightmap with distinct per-(x,y) values so every triangle plane
// is genuinely different from the others; flat / planar heightmaps
// would mask a triangle-pick bug because all four corners would
// give the same interpolated Z.
var heights = new byte[81];
for (int x = 0; x < 9; x++)
for (int y = 0; y < 9; y++)
heights[x * 9 + y] = (byte)((x * 17 + y * 13) % 256);
var hTable = LinearHeightTable();
// Pick a landblock where IsSplitSWtoNE(...) returns BOTH true and
// false across the 64 cells — Holtburg coords (0xA9, 0xB3) work.
const uint lbX = 0xA9, lbY = 0xB3;
var instance = new TerrainSurface(heights, hTable, lbX, lbY);
// Sample on a fine grid (~1500 points) covering all 64 cells and
// crossing every cell's diagonal boundary. A triangle-pick bug
// would show up as a >0.5 m Z mismatch on the diagonal-spanning
// cells (the corner heights vary by ~10 bytes = 10 Z each cell).
for (float lx = 0.5f; lx < 192f; lx += 5f)
for (float ly = 0.5f; ly < 192f; ly += 5f)
{
float instanceZ = instance.SampleZ(lx, ly);
float staticZ = TerrainSurface.SampleZFromHeightmap(
heights, hTable, lbX, lbY, lx, ly);
Assert.True(
Math.Abs(instanceZ - staticZ) < 0.0001f,
$"Z mismatch at ({lx:F1},{ly:F1}) lb=(0x{lbX:X},0x{lbY:X}): instance={instanceZ:F4} static={staticZ:F4}");
}
}
[Fact]
public void SampleZFromHeightmap_RejectsBadInputs()
{
var goodHeights = new byte[81];
var goodTable = LinearHeightTable();
Assert.Throws<ArgumentNullException>(() =>
TerrainSurface.SampleZFromHeightmap(null!, goodTable, 0, 0, 0f, 0f));
Assert.Throws<ArgumentNullException>(() =>
TerrainSurface.SampleZFromHeightmap(goodHeights, null!, 0, 0, 0f, 0f));
Assert.Throws<ArgumentException>(() =>
TerrainSurface.SampleZFromHeightmap(new byte[80], goodTable, 0, 0, 0f, 0f));
Assert.Throws<ArgumentException>(() =>
TerrainSurface.SampleZFromHeightmap(goodHeights, new float[255], 0, 0, 0f, 0f));
}
[Fact]
public void SampleSurfacePolygon_ReturnsContainingTriangleVertices()
{
var heights = FlatHeightmap(50);
var surface = new TerrainSurface(heights, LinearHeightTable(), landblockX: 0, landblockY: 0);
var sample = surface.SampleSurfacePolygon(2f, 2f);
Assert.Equal(3, sample.Vertices.Length);
for (int i = 0; i < sample.Vertices.Length; i++)
Assert.Equal(50f, sample.Vertices[i].Z);
Assert.Equal(1f, sample.Normal.Z, precision: 3);
Assert.True(
sample.Vertices.V0.X == 0f && sample.Vertices.V0.Y == 0f
|| sample.Vertices.V1.X == 0f && sample.Vertices.V1.Y == 0f
|| sample.Vertices.V2.X == 0f && sample.Vertices.V2.Y == 0f);
}
[Fact]
public void SampleNormalZFromHeightmap_FlatTerrain_ReturnsOne()
{
var heights = FlatHeightmap(50);
var hTable = LinearHeightTable();
float nz = TerrainSurface.SampleNormalZFromHeightmap(heights, hTable, 0, 0, 96f, 96f);
Assert.Equal(1f, nz, precision: 5);
}
[Fact]
public void SampleNormalZFromHeightmap_SlopedTerrain_ReturnsLessThanOne()
{
var heights = new byte[81];
for (int x = 0; x < 9; x++)
for (int y = 0; y < 9; y++)
heights[x * 9 + y] = (byte)(x * 20);
var hTable = LinearHeightTable();
float nz = TerrainSurface.SampleNormalZFromHeightmap(heights, hTable, 0, 0, 12f, 12f);
Assert.True(nz < 1f, $"Sloped terrain should have nz < 1.0, got {nz}");
Assert.True(nz > 0f, $"nz should be positive, got {nz}");
}
[Fact]
public void SampleNormalZFromHeightmap_AgreesWithSampleSurface()
{
var heights = new byte[81];
for (int x = 0; x < 9; x++)
for (int y = 0; y < 9; y++)
heights[x * 9 + y] = (byte)((x * 17 + y * 13) % 256);
var hTable = LinearHeightTable();
const uint lbX = 0xA9, lbY = 0xB3;
var instance = new TerrainSurface(heights, hTable, lbX, lbY);
for (float lx = 0.5f; lx < 192f; lx += 8f)
for (float ly = 0.5f; ly < 192f; ly += 8f)
{
var (_, normal) = instance.SampleSurface(lx, ly);
float staticNz = TerrainSurface.SampleNormalZFromHeightmap(
heights, hTable, lbX, lbY, lx, ly);
Assert.True(
Math.Abs(normal.Z - staticNz) < 0.0001f,
$"NormalZ mismatch at ({lx:F1},{ly:F1}): instance={normal.Z:F4} static={staticNz:F4}");
}
}
[Fact]
public void ComputeOutdoorCellId_Origin_ReturnsFirst()
{
var surface = new TerrainSurface(FlatHeightmap(), LinearHeightTable());
// Cell (0,0) at position (0,0) → cell ID 0x0001
Assert.Equal(0x0001u, surface.ComputeOutdoorCellId(0f, 0f));
}
[Fact]
public void ComputeOutdoorCellId_SecondColumn_ReturnsCorrect()
{
var surface = new TerrainSurface(FlatHeightmap(), LinearHeightTable());
// 24 units in X = cell (1, 0) → cell ID 0x0001 + 1*8 = 0x0009
Assert.Equal(0x0009u, surface.ComputeOutdoorCellId(24f, 0f));
}
[Fact]
public void ComputeOutdoorCellId_LastCell_Returns0x0040()
{
var surface = new TerrainSurface(FlatHeightmap(), LinearHeightTable());
// Cell (7,7) at position (191,191) → 0x0001 + 7*8 + 7 = 0x0040
Assert.Equal(0x0040u, surface.ComputeOutdoorCellId(191f, 191f));
}
}