P3D Named Selections
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Intro
placeholder till better organsied
MLOD
Named Selections are contained in the Taggs structure in MLOD file format. Every Tagg-name that doesn't have the form #Name# is a named selection. The name of the selection is simply the Tagg-name.
ulong NoOfBytes; //eg. Will always be lod.NoOfPoints + lod.NoOfFaces byte SelectedWeightedPoints[NoOfPoints]; byte SelectedFaces[NoOfFaces];
The weights are 'compressed' floating point values; the following functions may be used to encode/decode those values. The conversion functions were found by experimenting and are not guaranteed to yield the correct results.
NB: The byte array's indicate a zero-based offset into the corresponding Points & Faces structures.
To clarify, the purpose of this 'chunk' is to denote which points & faces belong to a given 'Named Selection' and also to denote the 'per-point-weight' associated with this selection.
Each byte in the SelectedWeightedPoints array denotes a value 0 to 255 (0 to FF hex).
And, serves a dual purpose in...
- 1. Denoting the selectedness and
- 2. Denoting per point weighting.
- Zero (0) or 0x00 hex indicates the corresponding point in the LODs Points array is not selected.
- Any value other than zero indicates that the point is not only part of the selection but also has a weighting value.
- One (1) or 0x01 hex indicates the corresponding point in the LODs Points array is selected and has 100% weighting.
- Every value between 2 and 255 (0x02 to 0xFF hex) indicates the percentage weight of the corresponding point and that it is part of the selection.
- Two (2) being almost 100% weighted and 255 being almost 0% weighted.
float32 byte2weight = (256 - weight)/255; if (byte2weight > 1.0) then byte2weight = 0;
Where 'weight' is a unit8 (single byte) in the range... 0 >= weight <= 255 or 0x00 >= weight <= 0xFF.
float decodeWeight( uint8 b )
{
if( b == 0 ) return 0.0f;
else if( b == 2 ) return 1.0f;
else if( b > 2 ) return 1.0f - round( (b-2) / 2.55555f )*0.01f;
else if( b < 0 ) return -round( b / 2.55555f ) * 0.01f;
else assert(false); // b == 1 does not occur?
}
unit8 weight2byte = round(256 - (255 x weight),0); if (weight2byte == 256) then weight2byte = 0;
Where 'weight' is a float32 in the range... 0.0 >= weight <= 1.0.
uint8 encodeWeight( float f )
{
// assume clamped value from 0.0 to 1.0
if( f < 0.01 ) return 0;
else if( f > 0.99 ) return 2;
else if( f > 0.5 ) return 0xff & (int)floor((1.0f - f) * 255.55f + 2);
else if( f > 0.49 ) return -127;
else return 0xff & (int)floor(f*2.5555f);
}
ODOL
All arrays are subject to the 1024 rule. Which type of compression depends on odol version
- ODOL7 and ODOL40: LZSS compressed
- Arma2: LZO compressed.
LodNamedSelection
{
asciiz SelectedName; // "rightleg" or "neck" eg
ulong NoOfFaces;
ushort FaceIndexes[NoOfFaces]; // indexing into the LodFaces Table
ulong Always0Count;
unknownType Array[Always0Count] //IsSectional must be true
///// ODOL7 only ///////////////////
ulong Count;
ulong UnknownV7Array[Count];
////////////////////////////////////
tbool IsSectional; //Appears in the sections[]= list of a model.cfg
ulong NoOfUlongs;
ulong SectionIndex[NoOfUlongs]; //IsSectional must be true. Indexes into the LodSections Table
ulong nVertices;
ushort VertexTableIndexes[nVertices];
ulong nTextureWeights;
byte VerticesWeights[nTextureWeights]; // if present they correspond to (are exentsions of) the VertexTableIndexes
}