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feat(app): add TerrainAtlas for GL_TEXTURE_2D_ARRAY terrain textures

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Erik 2026-04-10 20:19:36 +02:00
parent 78ce099440
commit 347a7e92ff
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src/AcDream.App/Rendering/TerrainAtlas.cs Normal file
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using AcDream.Core.Textures;
using DatReaderWriter;
using DatReaderWriter.DBObjs;
using DatReaderWriter.Enums;
using Silk.NET.OpenGL;
using DatPixelFormat = DatReaderWriter.Enums.PixelFormat;
using GLPixelFormat = Silk.NET.OpenGL.PixelFormat;
namespace AcDream.App.Rendering;
/// <summary>
/// Builds a GL_TEXTURE_2D_ARRAY from the set of terrain types seen in the loaded
/// landblocks, one layer per unique terrain type. LandblockMesh writes per-vertex
/// layer indices into Vertex.TerrainLayer; the terrain fragment shader samples
/// texture(uAtlas, vec3(uv, float(vLayer))).
/// </summary>
public sealed unsafe class TerrainAtlas : IDisposable
{
private readonly GL _gl;
public uint GlTexture { get; }
public IReadOnlyDictionary<uint, uint> TerrainTypeToLayer { get; }
public int LayerCount { get; }
private TerrainAtlas(GL gl, uint glTexture, IReadOnlyDictionary<uint, uint> map, int layerCount)
{
_gl = gl;
GlTexture = glTexture;
TerrainTypeToLayer = map;
LayerCount = layerCount;
}
/// <summary>
/// Build the atlas by walking Region.TerrainInfo.LandSurfaces.TexMerge.TerrainDesc
/// for the mapping from TerrainTextureType to SurfaceTexture id, decoding each
/// to RGBA8, and uploading as layers in a single GL_TEXTURE_2D_ARRAY.
/// </summary>
public static TerrainAtlas Build(GL gl, DatCollection dats)
{
var region = dats.Get<Region>(0x13000000u)
?? throw new InvalidOperationException("Region dat id 0x13000000 missing");
var terrainDesc = region.TerrainInfo?.LandSurfaces?.TexMerge?.TerrainDesc;
if (terrainDesc is null || terrainDesc.Count == 0)
{
// Fallback: upload a single 1x1 white layer as layer 0.
Console.WriteLine("WARN: TerrainDesc missing, using single white fallback layer");
return BuildFallback(gl);
}
// Walk TerrainDesc. Each TMTerrainDesc has a TerrainType (enum cast to uint)
// and a TerrainTex with a QualifiedDataId<SurfaceTexture> TextureId. Decode
// each referenced SurfaceTexture → RenderSurface → RGBA8 via SurfaceDecoder.
var decodedByType = new Dictionary<uint, DecodedTexture>();
int maxW = 1, maxH = 1;
foreach (var tmtd in terrainDesc)
{
uint typeKey = (uint)tmtd.TerrainType;
if (decodedByType.ContainsKey(typeKey))
continue;
var surfaceTextureId = (uint)tmtd.TerrainTex.TextureId;
var st = dats.Get<SurfaceTexture>(surfaceTextureId);
if (st is null || st.Textures.Count == 0)
{
Console.WriteLine($"WARN: TerrainType {tmtd.TerrainType} SurfaceTexture 0x{surfaceTextureId:X8} missing");
decodedByType[typeKey] = DecodedTexture.Magenta;
continue;
}
var rs = dats.Get<RenderSurface>((uint)st.Textures[0]);
if (rs is null)
{
decodedByType[typeKey] = DecodedTexture.Magenta;
continue;
}
Palette? palette = rs.DefaultPaletteId != 0
? dats.Get<Palette>(rs.DefaultPaletteId)
: null;
var decoded = SurfaceDecoder.DecodeRenderSurface(rs, palette);
decodedByType[typeKey] = decoded;
if (decoded.Width > maxW) maxW = decoded.Width;
if (decoded.Height > maxH) maxH = decoded.Height;
}
// Allocate the GL_TEXTURE_2D_ARRAY with the max dimensions seen. Textures
// smaller than (maxW, maxH) are scaled up naively by nearest-neighbor
// replication into a resized RGBA8 buffer. Phase 2b doesn't need mip chains.
int layerCount = decodedByType.Count;
uint tex = gl.GenTexture();
gl.BindTexture(TextureTarget.Texture2DArray, tex);
gl.TexImage3D(
TextureTarget.Texture2DArray, 0, InternalFormat.Rgba8,
(uint)maxW, (uint)maxH, (uint)layerCount,
0, GLPixelFormat.Rgba, PixelType.UnsignedByte, null);
var map = new Dictionary<uint, uint>();
int layerIdx = 0;
foreach (var kvp in decodedByType)
{
byte[] buffer = ResizeRgba8Nearest(kvp.Value, maxW, maxH);
fixed (byte* p = buffer)
{
gl.TexSubImage3D(
TextureTarget.Texture2DArray, 0,
0, 0, layerIdx,
(uint)maxW, (uint)maxH, 1,
GLPixelFormat.Rgba, PixelType.UnsignedByte, p);
}
map[kvp.Key] = (uint)layerIdx;
layerIdx++;
}
gl.TexParameter(TextureTarget.Texture2DArray, TextureParameterName.TextureMinFilter, (int)TextureMinFilter.Linear);
gl.TexParameter(TextureTarget.Texture2DArray, TextureParameterName.TextureMagFilter, (int)TextureMagFilter.Linear);
gl.TexParameter(TextureTarget.Texture2DArray, TextureParameterName.TextureWrapS, (int)TextureWrapMode.Repeat);
gl.TexParameter(TextureTarget.Texture2DArray, TextureParameterName.TextureWrapT, (int)TextureWrapMode.Repeat);
gl.BindTexture(TextureTarget.Texture2DArray, 0);
Console.WriteLine($"TerrainAtlas: {layerCount} layers at {maxW}x{maxH}");
return new TerrainAtlas(gl, tex, map, layerCount);
}
private static byte[] ResizeRgba8Nearest(DecodedTexture src, int dstW, int dstH)
{
if (src.Width == dstW && src.Height == dstH)
return src.Rgba8;
var dst = new byte[dstW * dstH * 4];
for (int y = 0; y < dstH; y++)
{
int srcY = y * src.Height / dstH;
for (int x = 0; x < dstW; x++)
{
int srcX = x * src.Width / dstW;
int si = (srcY * src.Width + srcX) * 4;
int di = (y * dstW + x) * 4;
dst[di + 0] = src.Rgba8[si + 0];
dst[di + 1] = src.Rgba8[si + 1];
dst[di + 2] = src.Rgba8[si + 2];
dst[di + 3] = src.Rgba8[si + 3];
}
}
return dst;
}
private static TerrainAtlas BuildFallback(GL gl)
{
uint tex = gl.GenTexture();
gl.BindTexture(TextureTarget.Texture2DArray, tex);
var white = new byte[] { 0xFF, 0xFF, 0xFF, 0xFF };
gl.TexImage3D(TextureTarget.Texture2DArray, 0, InternalFormat.Rgba8, 1, 1, 1, 0, GLPixelFormat.Rgba, PixelType.UnsignedByte, null);
fixed (byte* p = white)
gl.TexSubImage3D(TextureTarget.Texture2DArray, 0, 0, 0, 0, 1, 1, 1, GLPixelFormat.Rgba, PixelType.UnsignedByte, p);
gl.TexParameter(TextureTarget.Texture2DArray, TextureParameterName.TextureMinFilter, (int)TextureMinFilter.Linear);
gl.TexParameter(TextureTarget.Texture2DArray, TextureParameterName.TextureMagFilter, (int)TextureMagFilter.Linear);
gl.BindTexture(TextureTarget.Texture2DArray, 0);
return new TerrainAtlas(gl, tex, new Dictionary<uint, uint> { [0] = 0u }, 1);
}
public void Dispose() => _gl.DeleteTexture(GlTexture);
}