LayerData
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Message Layout
{ LayerData High Trusted Unencoded { LayerID Single { Type U8 } } { LayerData Single { Data Variable 2 } } }
Usage and Notes
LayerData packets transmit terrain, wind, and cloud information using a custom IDCT routine similar to JPEG but with different coefficients. The data in these packets is stored in a proprietary format of 16x16 meter blocks.
Type:
- 76 : LLSurface (terrain) - 55 : LLWind (wind) - 56 : LLCloudLayer (Cloud)
Data:
- [patchgroupSize] - uint8
- [quant_wbits] - uint8
- [patchHeader]
- [patchSize] - uint8
- [dc_offset] - uint32
- [range] - uin16
- [patchIDs] - 10 bit unsigned integer
- [patchData]
- [zeroCode] - One bit. If 0, the data is zerocoded
- [hasData] - One bit, If 0, the entire patch is zeros.
- [data] - has a size of (patchSize % 16) + 2
- [data] ... - repeat until patchSize has been read
- [patchHeader] ... - repeat until patchgroupSize has been read
- ...
The data then has to be decompressed, and I have no idea how this data is used.
You may find some use from the psuedocode at LibSecondLife.org