-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy pathLithTechModelDecoder.cs
More file actions
1689 lines (1468 loc) · 55.7 KB
/
LithTechModelDecoder.cs
File metadata and controls
1689 lines (1468 loc) · 55.7 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
using System.Buffers.Binary;
using System.Diagnostics;
using System.Globalization;
using System.IO;
using System.Text;
namespace CFRezManager;
public sealed record LithTechModelDocument(
string Name,
IReadOnlyList<LithTechMesh> Meshes,
string StorageDescription,
int SourceByteCount,
int DecodedByteCount)
{
public int VertexCount => Meshes.Sum(mesh => mesh.Vertices.Count);
public int TriangleCount => Meshes.Sum(mesh => mesh.TriangleIndices.Count / 3);
}
public sealed record LithTechMesh(
string Name,
IReadOnlyList<LithTechVector3> Vertices,
IReadOnlyList<int> TriangleIndices,
IReadOnlyList<LithTechVector2>? TextureCoordinates = null,
string? TexturePath = null)
{
public bool HasTextureCoordinates => TextureCoordinates is not null && TextureCoordinates.Count == Vertices.Count;
}
public readonly record struct LithTechVector3(double X, double Y, double Z);
public readonly record struct LithTechVector2(double X, double Y);
internal static class LithTechModelDecoder
{
private const int MaxParseDepth = 256;
private const int MaxLtbMeshCount = 4096;
private const int ExternalConverterTimeoutMilliseconds = 15_000;
// Offsets follow Cote-Duke's LTB2X loader notes for LithTech Jupiter LTB meshes.
private const int LtbCommandLineLengthOffset = 84;
private const int LtbMeshCountOffset = 86 + 8;
private const int LtbFirstMeshOffset = 86 + 12;
private const int LtbMeshVertexCountOffset = 49;
private const int LtbMeshFaceCountOffset = 53;
private const int LtbMeshTypeHeadOffset = 57;
private const int LtbMeshTypeOffset = 61;
private const int LtbFirstVertexOffset = 83;
private const int LtbFirstVertexDoubleStartOffset = 85;
private const ushort LtbMeshTypeNotSkinned = 1;
private const ushort LtbMeshTypeExtraFloat = 2;
private const ushort LtbMeshTypeSkinnedAlt = 3;
private const ushort LtbMeshTypeSkinned = 4;
private const ushort LtbMeshTypeTwoExtraFloats = 5;
private const ushort LtbMeshTypeSkinnedExtraFloat = 6;
private static readonly string[] TextureExtensions = [".dtx", ".dds", ".tga", ".png", ".jpg", ".jpeg", ".bmp"];
private static readonly string[] LtaTextureCoordinateHeads =
[
"uv",
"uvs",
"uv-fs",
"uvs-fs",
"tvert",
"tverts",
"texvert",
"texverts",
"texcoord",
"texcoords",
"texturecoord",
"texturecoords",
"texture-coordinate",
"texture-coordinates"
];
static LithTechModelDecoder()
{
Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);
}
public static bool IsCandidate(string extension)
{
return string.Equals(extension, "lta", StringComparison.OrdinalIgnoreCase) ||
string.Equals(extension, "ltb", StringComparison.OrdinalIgnoreCase) ||
string.Equals(extension, "ltc", StringComparison.OrdinalIgnoreCase);
}
public static bool TryDecode(byte[] data, string fallbackName, out LithTechModelDocument? document)
{
return TryDecode(data, fallbackName, "lta", out document, out _);
}
public static bool TryDecode(
byte[] data,
string fallbackName,
string extension,
out LithTechModelDocument? document,
out string? errorMessage)
{
document = null;
errorMessage = null;
if (string.Equals(extension, "ltc", StringComparison.OrdinalIgnoreCase))
{
return TryDecodeLtc(data, fallbackName, out document, out errorMessage);
}
byte[]? prepared = LzmaAloneDecoder.TryPrepareData(data);
if (prepared is null)
{
errorMessage = LocalizedText.T("ModelOuterCompressionFailed");
return false;
}
if (string.Equals(extension, "ltb", StringComparison.OrdinalIgnoreCase))
{
string nativeStorageDescription = ReferenceEquals(prepared, data) ? "LTB binary" : "LZMA-compressed LTB";
if (TryParseLtbBinary(prepared, fallbackName, nativeStorageDescription, data.Length, prepared.Length, out document, out errorMessage))
{
return true;
}
string? nativeError = errorMessage;
string? ltaText = TryConvertLtbToLtaText(prepared, fallbackName, out string? converterError);
if (ltaText is null)
{
errorMessage = string.IsNullOrWhiteSpace(converterError)
? nativeError
: $"{nativeError} {converterError}";
return false;
}
string ltbStorageDescription = ReferenceEquals(prepared, data)
? "LTB -> LTA"
: "LZMA-compressed LTB -> LTA";
return TryParseLtaText(ltaText, fallbackName, ltbStorageDescription, data.Length, prepared.Length, out document, out errorMessage);
}
string storageDescription = ReferenceEquals(prepared, data) ? "LTA text" : "LZMA-compressed LTA";
string text = Encoding.ASCII.GetString(prepared);
return TryParseLtaText(text, fallbackName, storageDescription, data.Length, prepared.Length, out document, out errorMessage);
}
private static bool TryDecodeLtc(
byte[] data,
string fallbackName,
out LithTechModelDocument? document,
out string? errorMessage)
{
document = null;
errorMessage = null;
byte[]? prepared = LzmaAloneDecoder.TryPrepareData(data);
if (prepared is not null)
{
string ltaText = Encoding.ASCII.GetString(prepared);
if (ltaText.Contains("(lt-model", StringComparison.OrdinalIgnoreCase) &&
TryParseLtaText(
ltaText,
fallbackName,
ReferenceEquals(prepared, data) ? "LTC text" : "LZMA-compressed LTC",
data.Length,
prepared.Length,
out document,
out errorMessage))
{
return true;
}
}
if (CrossFireLtcDecoder.TryConvertToText(data, fallbackName, out CrossFireLtcTextDocument? converted, out string? converterError) &&
converted is not null)
{
return TryParseLtaText(converted.Text, fallbackName, converted.StorageDescription, data.Length, converted.DecodedByteCount, out document, out errorMessage);
}
if (CrossFireLtcDecoder.HasCrossFireMagic(data))
{
errorMessage = CrossFireLtcDecoder.GetUnsupportedMessage(converterError);
return false;
}
errorMessage = string.IsNullOrWhiteSpace(converterError)
? LocalizedText.T("ModelLtcNotRecognized")
: converterError;
return false;
}
private static bool TryParseLtbBinary(
byte[] rawLtb,
string fallbackName,
string storageDescription,
int sourceByteCount,
int decodedByteCount,
out LithTechModelDocument? document,
out string? errorMessage)
{
document = null;
errorMessage = null;
ReadOnlySpan<byte> data = rawLtb;
string? firstParseError = null;
foreach (LtbMeshTableCandidate candidate in GetLtbMeshTableCandidates(data))
{
if (TryParseLtbMeshes(data, candidate.FirstMeshOffset, candidate.MeshCount, out List<LithTechMesh>? meshes, out string? candidateError) &&
meshes is not null)
{
document = new LithTechModelDocument(fallbackName, meshes, storageDescription, sourceByteCount, decodedByteCount);
return true;
}
firstParseError ??= candidateError;
}
if (!string.IsNullOrWhiteSpace(firstParseError))
{
errorMessage = firstParseError;
return false;
}
if (!TryReadUInt16(data, LtbCommandLineLengthOffset, out ushort commandLineLength))
{
errorMessage = LocalizedText.T("LtbTooShort");
return false;
}
int meshCountOffset = LtbMeshCountOffset + commandLineLength;
int position = LtbFirstMeshOffset + commandLineLength;
if (!TryReadUInt32(data, meshCountOffset, out uint meshCount))
{
errorMessage = LocalizedText.T("LtbHeaderIncompleteMeshCount");
return false;
}
if (meshCount == 0 || meshCount > MaxLtbMeshCount)
{
errorMessage = LocalizedText.Format("LtbInvalidMeshCount", meshCount);
return false;
}
errorMessage = LocalizedText.T("LtbNoPreviewMesh");
return false;
}
private static List<LtbMeshTableCandidate> GetLtbMeshTableCandidates(ReadOnlySpan<byte> data)
{
var candidates = new List<LtbMeshTableCandidate>();
var seenFirstMeshOffsets = new HashSet<int>();
if (TryReadUInt16(data, LtbCommandLineLengthOffset, out ushort commandLineLength))
{
int meshCountOffset = LtbMeshCountOffset + commandLineLength;
int firstMeshOffset = LtbFirstMeshOffset + commandLineLength;
if (TryReadUInt32(data, meshCountOffset, out uint meshCount) &&
IsPlausibleLtbMeshCount(meshCount) &&
seenFirstMeshOffsets.Add(firstMeshOffset))
{
candidates.Add(new LtbMeshTableCandidate(meshCountOffset, firstMeshOffset, meshCount));
}
}
int scanLimit = Math.Min(data.Length - 2, 4096);
for (int firstMeshOffset = 4; firstMeshOffset <= scanLimit; firstMeshOffset++)
{
int meshCountOffset = firstMeshOffset - sizeof(uint);
if (!TryReadUInt32(data, meshCountOffset, out uint meshCount) ||
!IsPlausibleLtbMeshCount(meshCount) ||
!seenFirstMeshOffsets.Add(firstMeshOffset))
{
continue;
}
if (LooksLikeLtbMeshAt(data, firstMeshOffset))
{
candidates.Add(new LtbMeshTableCandidate(meshCountOffset, firstMeshOffset, meshCount));
}
}
return candidates;
}
private static bool IsPlausibleLtbMeshCount(uint meshCount)
{
return meshCount > 0 && meshCount <= MaxLtbMeshCount;
}
private static bool LooksLikeLtbMeshAt(ReadOnlySpan<byte> data, int position)
{
if (!TryReadUInt16(data, position, out ushort nameLength) ||
nameLength > 512)
{
return false;
}
int nameStart = position + sizeof(ushort);
int meshBaseOffset = nameStart + nameLength;
if (nameStart < 0 ||
meshBaseOffset < 0 ||
meshBaseOffset + LtbFirstVertexOffset >= data.Length ||
!LooksLikeLtbStringBytes(data.Slice(nameStart, nameLength)))
{
return false;
}
if (!TryReadUInt16(data, meshBaseOffset + LtbMeshVertexCountOffset, out ushort vertexCount) ||
!TryReadUInt16(data, meshBaseOffset + LtbMeshFaceCountOffset, out ushort faceCount) ||
vertexCount == 0 ||
faceCount == 0)
{
return false;
}
return TryFindLtbMeshLayout(
data,
meshBaseOffset,
vertexCount,
faceCount,
GetLtbVertexLookupByteCount(data),
requireFollowingMesh: false,
out _,
out _,
out _,
out _,
out _,
out _);
}
private static bool LooksLikeLtbStringBytes(ReadOnlySpan<byte> bytes)
{
if (bytes.IsEmpty)
{
return true;
}
bool sawText = false;
foreach (byte value in bytes)
{
if (value == 0)
{
continue;
}
if (value < 0x20 && value != (byte)'\t')
{
return false;
}
sawText = true;
}
return sawText;
}
private static bool LooksLikeLtbMeshHeaderAt(ReadOnlySpan<byte> data, int position)
{
if (!TryReadUInt16(data, position, out ushort nameLength) ||
nameLength > 512)
{
return false;
}
int nameStart = position + sizeof(ushort);
int meshBaseOffset = nameStart + nameLength;
if (nameStart < 0 ||
meshBaseOffset < 0 ||
meshBaseOffset + LtbFirstVertexOffset >= data.Length ||
!LooksLikeLtbStringBytes(data.Slice(nameStart, nameLength)))
{
return false;
}
return TryReadUInt16(data, meshBaseOffset + LtbMeshVertexCountOffset, out ushort vertexCount) &&
TryReadUInt16(data, meshBaseOffset + LtbMeshFaceCountOffset, out ushort faceCount) &&
vertexCount > 0 &&
faceCount > 0;
}
private static bool TryParseLtbMeshes(
ReadOnlySpan<byte> data,
int firstMeshOffset,
uint meshCount,
out List<LithTechMesh>? meshes,
out string? errorMessage)
{
meshes = null;
errorMessage = null;
var parsedMeshes = new List<LithTechMesh>((int)Math.Min(meshCount, 64));
int position = firstMeshOffset;
int vertexLookupByteCount = GetLtbVertexLookupByteCount(data);
List<string> texturePaths = ExtractEmbeddedTexturePaths(data);
for (int meshIndex = 0; meshIndex < meshCount; meshIndex++)
{
if (!TryReadLtbString(data, ref position, out string meshName))
{
errorMessage = LocalizedText.Format("LtbMeshNameIncomplete", meshIndex + 1);
return false;
}
int meshBaseOffset = position;
bool requireFollowingMesh = meshIndex + 1 < meshCount;
if (!TryReadLtbMesh(
data,
meshName,
meshIndex,
meshBaseOffset,
vertexLookupByteCount,
requireFollowingMesh,
texturePaths,
out LithTechMesh? mesh,
out position,
out errorMessage))
{
return false;
}
if (mesh is not null)
{
parsedMeshes.Add(mesh);
}
}
if (parsedMeshes.Count == 0)
{
errorMessage = LocalizedText.T("LtbNoPreviewMesh");
return false;
}
meshes = parsedMeshes;
return true;
}
private static bool TryReadLtbMesh(
ReadOnlySpan<byte> data,
string meshName,
int meshIndex,
int meshBaseOffset,
int vertexLookupByteCount,
bool requireFollowingMesh,
IReadOnlyList<string> texturePaths,
out LithTechMesh? mesh,
out int nextPosition,
out string? errorMessage)
{
mesh = null;
nextPosition = meshBaseOffset;
errorMessage = null;
if (!TryReadUInt16(data, meshBaseOffset + LtbMeshVertexCountOffset, out ushort vertexCount) ||
!TryReadUInt16(data, meshBaseOffset + LtbMeshFaceCountOffset, out ushort faceCount))
{
errorMessage = LocalizedText.Format("LtbMeshHeaderIncomplete", meshName);
return false;
}
if (!TryFindLtbMeshLayout(
data,
meshBaseOffset,
vertexCount,
faceCount,
vertexLookupByteCount,
requireFollowingMesh,
out LtbMeshLayout layout,
out ushort meshType,
out int vertexDataOffset,
out int indexDataOffset,
out nextPosition,
out errorMessage))
{
errorMessage ??= LocalizedText.Format("LtbUnsupportedMeshType", meshName, meshType);
return false;
}
int indexCount = faceCount * 3;
var vertices = new List<LithTechVector3>(vertexCount);
var textureCoordinates = new List<LithTechVector2>(vertexCount);
int readPosition = vertexDataOffset;
for (int vertexIndex = 0; vertexIndex < vertexCount; vertexIndex++)
{
if (!TryReadSingle(data, readPosition, out float x) ||
!TryReadSingle(data, readPosition + 4, out float y) ||
!TryReadSingle(data, readPosition + 8, out float z))
{
errorMessage = LocalizedText.Format("LtbMeshVertexIncomplete", meshName, vertexIndex + 1);
return false;
}
vertices.Add(new LithTechVector3(x, y, z));
if (TryReadSingle(data, readPosition + layout.TextureCoordinateOffset, out float u) &&
TryReadSingle(data, readPosition + layout.TextureCoordinateOffset + sizeof(float), out float v))
{
textureCoordinates.Add(new LithTechVector2(u, v));
}
readPosition += layout.VertexStride;
}
var triangleIndices = new List<int>(indexCount);
readPosition = indexDataOffset;
for (int index = 0; index < indexCount; index++)
{
if (!TryReadUInt16(data, readPosition, out ushort triangleIndex))
{
errorMessage = LocalizedText.Format("LtbMeshIndexDataIncomplete", meshName);
return false;
}
if (triangleIndex >= vertexCount)
{
errorMessage = LocalizedText.Format("LtbMeshIndexOutOfRange", meshName, triangleIndex);
return false;
}
triangleIndices.Add(triangleIndex);
readPosition += sizeof(ushort);
}
if (vertices.Count > 0 && triangleIndices.Count >= 3)
{
string displayName = string.IsNullOrWhiteSpace(meshName) ? $"Mesh {meshIndex + 1}" : meshName;
mesh = new LithTechMesh(
displayName,
vertices,
triangleIndices,
textureCoordinates.Count == vertices.Count ? textureCoordinates : null,
ResolveTexturePath(texturePaths, displayName, meshIndex));
}
return true;
}
private static bool TryFindLtbMeshLayout(
ReadOnlySpan<byte> data,
int meshBaseOffset,
ushort vertexCount,
ushort faceCount,
int vertexLookupByteCount,
bool requireFollowingMesh,
out LtbMeshLayout layout,
out ushort meshType,
out int vertexDataOffset,
out int indexDataOffset,
out int nextPosition,
out string? errorMessage)
{
layout = default;
meshType = 0;
vertexDataOffset = 0;
indexDataOffset = 0;
nextPosition = meshBaseOffset;
errorMessage = null;
Span<int> vertexDataOffsets = stackalloc int[96];
int vertexDataOffsetCount = GetLtbVertexDataOffsetCandidates(data, meshBaseOffset, vertexLookupByteCount, vertexDataOffsets);
if (vertexDataOffsetCount == 0)
{
errorMessage = LocalizedText.T("LtbMeshVertexDataIncomplete");
return false;
}
Span<ushort> meshTypes = stackalloc ushort[8];
int meshTypeCount = GetLtbMeshTypeCandidates(data, meshBaseOffset, meshTypes);
if (meshTypeCount == 0)
{
errorMessage = LocalizedText.T("LtbMeshTypeDataIncomplete");
return false;
}
int indexCount = faceCount * 3;
long indexByteCount = (long)indexCount * sizeof(ushort);
Span<int> candidateNextPositions = stackalloc int[4];
for (int offsetIndex = 0; offsetIndex < vertexDataOffsetCount; offsetIndex++)
{
int candidateVertexDataOffset = vertexDataOffsets[offsetIndex];
for (int i = 0; i < meshTypeCount; i++)
{
ushort candidateType = meshTypes[i];
if (!TryCreateLtbMeshLayout(candidateType, out LtbMeshLayout candidateLayout))
{
continue;
}
long vertexByteCount = (long)vertexCount * candidateLayout.VertexStride;
if (vertexByteCount > int.MaxValue ||
indexByteCount > int.MaxValue ||
candidateVertexDataOffset < 0 ||
candidateVertexDataOffset + vertexByteCount + indexByteCount > data.Length)
{
errorMessage = LocalizedText.T("LtbMeshGeometryOutOfRange");
continue;
}
int candidateIndexDataOffset = candidateVertexDataOffset + (int)vertexByteCount;
if (!AreLtbTriangleIndicesInRange(data, candidateIndexDataOffset, indexCount, vertexCount))
{
errorMessage = LocalizedText.T("LtbMeshIndexOutOfRangeGeneric");
continue;
}
int postDataPosition = candidateIndexDataOffset + (int)indexByteCount;
int candidateNextPositionCount = GetLtbMeshPostDataEndCandidates(
data,
candidateLayout,
postDataPosition,
allowNoPostData: !requireFollowingMesh,
scanForNextMesh: requireFollowingMesh,
candidateNextPositions);
if (candidateNextPositionCount == 0)
{
errorMessage = LocalizedText.T("LtbMeshTrailingDataIncomplete");
continue;
}
for (int nextIndex = 0; nextIndex < candidateNextPositionCount; nextIndex++)
{
int candidateNextPosition = candidateNextPositions[nextIndex];
if (requireFollowingMesh && !LooksLikeLtbMeshAt(data, candidateNextPosition))
{
errorMessage = LocalizedText.T("LtbMeshTrailingAlignmentFailed");
continue;
}
layout = candidateLayout;
meshType = candidateType;
vertexDataOffset = candidateVertexDataOffset;
indexDataOffset = candidateIndexDataOffset;
nextPosition = candidateNextPosition;
errorMessage = null;
return true;
}
}
}
return false;
}
private static int GetLtbVertexLookupByteCount(ReadOnlySpan<byte> data)
{
if (!TryReadUInt32(data, 32, out uint nodeCount) ||
nodeCount == 0 ||
nodeCount > 4096)
{
return 0;
}
return ((int)nodeCount + 1) * sizeof(uint);
}
private static int GetLtbVertexDataOffsetCandidates(ReadOnlySpan<byte> data, int meshBaseOffset, int vertexLookupByteCount, Span<int> offsets)
{
int count = 0;
if (TryGetLtbVertexDataOffset(data, meshBaseOffset, out int detectedOffset))
{
AddLtbVertexDataOffsetCandidate(offsets, ref count, detectedOffset, data.Length);
}
AddLtbVertexDataOffsetCandidate(offsets, ref count, meshBaseOffset + LtbFirstVertexOffset, data.Length);
AddLtbVertexDataOffsetCandidate(offsets, ref count, meshBaseOffset + LtbFirstVertexDoubleStartOffset, data.Length);
AddLtbVertexDataOffsetCandidate(offsets, ref count, meshBaseOffset + LtbFirstVertexDoubleStartOffset + sizeof(ushort), data.Length);
if (vertexLookupByteCount > 0)
{
AddLtbVertexDataOffsetCandidate(offsets, ref count, meshBaseOffset + LtbFirstVertexOffset + vertexLookupByteCount, data.Length);
}
int vertexLookupFlagOffset = meshBaseOffset + 65;
if (vertexLookupFlagOffset >= 0 &&
vertexLookupFlagOffset < data.Length &&
data[vertexLookupFlagOffset] != 0)
{
int scanStart = meshBaseOffset + LtbFirstVertexOffset;
int scanEnd = Math.Min(scanStart + 320, data.Length - sizeof(float) * 3);
for (int offset = scanStart; offset <= scanEnd; offset += sizeof(uint))
{
AddLtbVertexDataOffsetCandidate(offsets, ref count, offset, data.Length);
}
}
return count;
}
private static void AddLtbVertexDataOffsetCandidate(Span<int> offsets, ref int count, int offset, int dataLength)
{
if (offset < 0 || offset >= dataLength)
{
return;
}
for (int i = 0; i < count; i++)
{
if (offsets[i] == offset)
{
return;
}
}
if (count < offsets.Length)
{
offsets[count++] = offset;
}
}
private static int GetLtbMeshTypeCandidates(ReadOnlySpan<byte> data, int meshBaseOffset, Span<ushort> meshTypes)
{
if (!TryReadUInt16(data, meshBaseOffset + LtbMeshTypeHeadOffset, out ushort meshTypeHead) ||
!TryReadUInt16(data, meshBaseOffset + LtbMeshTypeOffset, out ushort meshTypeOffset))
{
return 0;
}
int count = 0;
if (meshTypeHead == LtbMeshTypeSkinnedAlt)
{
AddLtbMeshTypeCandidate(meshTypes, ref count, LtbMeshTypeTwoExtraFloats);
}
else if (IsKnownLtbMeshType(meshTypeHead))
{
AddLtbMeshTypeCandidate(meshTypes, ref count, meshTypeHead);
}
if (IsKnownLtbMeshType(meshTypeOffset))
{
AddLtbMeshTypeCandidate(meshTypes, ref count, meshTypeOffset);
}
AddLtbMeshTypeCandidate(meshTypes, ref count, LtbMeshTypeNotSkinned);
AddLtbMeshTypeCandidate(meshTypes, ref count, LtbMeshTypeExtraFloat);
AddLtbMeshTypeCandidate(meshTypes, ref count, LtbMeshTypeTwoExtraFloats);
AddLtbMeshTypeCandidate(meshTypes, ref count, LtbMeshTypeSkinnedExtraFloat);
AddLtbMeshTypeCandidate(meshTypes, ref count, LtbMeshTypeSkinned);
AddLtbMeshTypeCandidate(meshTypes, ref count, LtbMeshTypeSkinnedAlt);
return count;
}
private static void AddLtbMeshTypeCandidate(Span<ushort> meshTypes, ref int count, ushort meshType)
{
for (int i = 0; i < count; i++)
{
if (meshTypes[i] == meshType)
{
return;
}
}
if (count < meshTypes.Length)
{
meshTypes[count++] = meshType;
}
}
private static bool IsKnownLtbMeshType(ushort meshType)
{
return meshType is LtbMeshTypeNotSkinned or
LtbMeshTypeExtraFloat or
LtbMeshTypeSkinnedAlt or
LtbMeshTypeSkinned or
LtbMeshTypeTwoExtraFloats or
LtbMeshTypeSkinnedExtraFloat;
}
private static bool TryCreateLtbMeshLayout(ushort meshType, out LtbMeshLayout layout)
{
layout = meshType switch
{
LtbMeshTypeNotSkinned => new LtbMeshLayout(IncludeWeights: false, IncludePostData: false, PostNormalByteCount: 0),
LtbMeshTypeExtraFloat => new LtbMeshLayout(IncludeWeights: false, IncludePostData: true, PostNormalByteCount: sizeof(float)),
LtbMeshTypeSkinned => new LtbMeshLayout(IncludeWeights: true, IncludePostData: true, PostNormalByteCount: 0),
LtbMeshTypeSkinnedAlt => new LtbMeshLayout(IncludeWeights: true, IncludePostData: true, PostNormalByteCount: 0),
LtbMeshTypeTwoExtraFloats => new LtbMeshLayout(IncludeWeights: false, IncludePostData: true, PostNormalByteCount: sizeof(float) * 2),
LtbMeshTypeSkinnedExtraFloat => new LtbMeshLayout(IncludeWeights: true, IncludePostData: true, PostNormalByteCount: sizeof(float)),
_ => default
};
return IsKnownLtbMeshType(meshType);
}
private static bool AreLtbTriangleIndicesInRange(ReadOnlySpan<byte> data, int position, int indexCount, ushort vertexCount)
{
for (int index = 0; index < indexCount; index++)
{
if (!TryReadUInt16(data, position, out ushort triangleIndex) ||
triangleIndex >= vertexCount)
{
return false;
}
position += sizeof(ushort);
}
return true;
}
private static bool TryGetLtbVertexDataOffset(ReadOnlySpan<byte> data, int meshBaseOffset, out int vertexDataOffset)
{
vertexDataOffset = 0;
int markerOffset = meshBaseOffset + LtbFirstVertexOffset;
if (markerOffset < 0 || markerOffset + 4 > data.Length)
{
return false;
}
ReadOnlySpan<byte> marker = data[markerOffset..(markerOffset + 4)];
int relativeOffset = marker[0] == 0 && marker[1] == 0 && marker[2] != 0 && marker[3] != 0
? LtbFirstVertexDoubleStartOffset
: LtbFirstVertexOffset;
vertexDataOffset = meshBaseOffset + relativeOffset;
return vertexDataOffset >= 0 && vertexDataOffset < data.Length;
}
private static int GetLtbMeshPostDataEndCandidates(
ReadOnlySpan<byte> data,
LtbMeshLayout layout,
int position,
bool allowNoPostData,
bool scanForNextMesh,
Span<int> positions)
{
int count = 0;
if (allowNoPostData)
{
AddLtbPostDataEndCandidate(positions, ref count, position, data.Length);
}
if (!layout.IncludePostData)
{
AddLtbPostDataEndCandidate(positions, ref count, position + sizeof(ushort), data.Length);
}
if (TryReadUInt32(data, position, out uint sectionCount) &&
sectionCount <= 4096)
{
long sectionEnd = (long)position + sizeof(uint) + (long)sectionCount * 12;
if (sectionEnd >= 0 && sectionEnd <= data.Length)
{
AddLtbPostDataEndCandidate(positions, ref count, (int)sectionEnd, data.Length);
AddLtbPostDataEndCandidate(positions, ref count, (int)sectionEnd + sizeof(uint), data.Length);
if (sectionEnd < data.Length)
{
int finalSectionSize = data[(int)sectionEnd];
AddLtbPostDataEndCandidate(positions, ref count, (int)sectionEnd + 1 + finalSectionSize, data.Length);
}
}
}
if (scanForNextMesh)
{
int scanEnd = Math.Min(position + 128, data.Length - LtbFirstVertexOffset);
for (int candidatePosition = position; candidatePosition <= scanEnd; candidatePosition++)
{
if (LooksLikeLtbMeshHeaderAt(data, candidatePosition))
{
AddLtbPostDataEndCandidate(positions, ref count, candidatePosition, data.Length);
}
}
}
return count;
}
private static void AddLtbPostDataEndCandidate(Span<int> positions, ref int count, int position, int dataLength)
{
if (position < 0 || position > dataLength)
{
return;
}
for (int i = 0; i < count; i++)
{
if (positions[i] == position)
{
return;
}
}
if (count < positions.Length)
{
positions[count++] = position;
}
}
private static bool TryReadLtbString(ReadOnlySpan<byte> data, ref int position, out string value)
{
value = string.Empty;
if (!TryReadUInt16(data, position, out ushort length))
{
return false;
}
position += sizeof(ushort);
if (position < 0 || position + length > data.Length)
{
return false;
}
value = DecodeLtbString(data.Slice(position, length));
position += length;
return true;
}
private static string DecodeLtbString(ReadOnlySpan<byte> bytes)
{
if (bytes.IsEmpty)
{
return string.Empty;
}
try
{
return Encoding.GetEncoding(949).GetString(bytes).TrimEnd('\0');
}
catch
{
return Encoding.ASCII.GetString(bytes).TrimEnd('\0');
}
}
private static bool TryReadUInt16(ReadOnlySpan<byte> data, int offset, out ushort value)
{
value = 0;
if (offset < 0 || offset + sizeof(ushort) > data.Length)
{
return false;
}
value = BinaryPrimitives.ReadUInt16LittleEndian(data.Slice(offset, sizeof(ushort)));
return true;
}
private static bool TryReadUInt32(ReadOnlySpan<byte> data, int offset, out uint value)
{
value = 0;
if (offset < 0 || offset + sizeof(uint) > data.Length)
{
return false;
}
value = BinaryPrimitives.ReadUInt32LittleEndian(data.Slice(offset, sizeof(uint)));
return true;
}
private static bool TryReadSingle(ReadOnlySpan<byte> data, int offset, out float value)
{
value = 0;
if (offset < 0 || offset + sizeof(float) > data.Length)
{
return false;
}
int bits = BinaryPrimitives.ReadInt32LittleEndian(data.Slice(offset, sizeof(float)));
value = BitConverter.Int32BitsToSingle(bits);
return true;
}
internal static bool TryParseLtaText(
string text,
string fallbackName,
string storageDescription,
int sourceByteCount,
int decodedByteCount,
out LithTechModelDocument? document,
out string? errorMessage)
{
document = null;
errorMessage = null;
try
{
var parser = new LtaParser(text);
LtaList root = parser.ParseRoot();
string rootHead = GetAtomValue(root.Items.FirstOrDefault()) ?? string.Empty;
bool isWorld = string.Equals(rootHead, "world", StringComparison.OrdinalIgnoreCase);
bool isModel = string.Equals(rootHead, "lt-model", StringComparison.OrdinalIgnoreCase) ||
text.Contains("(lt-model", StringComparison.OrdinalIgnoreCase);
List<LithTechMesh> meshes;
string documentStorageDescription = storageDescription;
if (isWorld)
{
meshes = ParseWorldMeshes(root);
documentStorageDescription = $"{storageDescription} world";
}
else if (isModel)
{
meshes = FindListsByHead(root, "mesh")
.Select(ParseMesh)
.Where(mesh => mesh is not null)
.Cast<LithTechMesh>()
.ToList();
}
else
{
errorMessage = "LTA text is not a recognized model or world document.";
return false;
}
if (meshes.Count == 0)
{