The Basis Universal "supercompression global data" a
supercompressionScheme == basisLZ file carries: the endpoint and
selector codebooks, the per-block bitstream's Huffman tables, and one
ImageDesc per image telling where in the level's own bytes the RGB (and
optionally alpha) slice lives.
Verified against a real encoded file — see
flutter3d_samples/doc/ktx2_fixtures.md — not only against the
specification text, which for this section is thinner than the container
layout above.
Global data header, at sgdByteOffset, 20 bytes
u16 endpointCount, u16 selectorCount
u32 endpointsByteLength
u32 selectorsByteLength
u32 tablesByteLength
u32 extendedByteLength
ImageDesc, 20 bytes, one per image — with no layers and one face an
image is a mip level, so this stage reads `levelCount` of them, entry 0
being level 0, whatever order the levels' bytes sit in the file
u32 imageFlags
u32 rgbSliceByteOffset, u32 rgbSliceByteLength
u32 alphaSliceByteOffset, u32 alphaSliceByteLength
Then, back to back: endpointsData, selectorsData, tablesData.
The slice offsets are relative to the level's bytes (the ones the
ordinary KTX2 level index in ktx2_loader.dart already finds) — not to
this section — confirmed on the real file: rgbSliceByteOffset was 0
and the level's own bytes started elsewhere in the file entirely.
Properties
- hashCode → int
-
The hash code for this object.
no setterinherited
- runtimeType → Type
-
A representation of the runtime type of the object.
no setterinherited
Methods
-
noSuchMethod(
Invocation invocation) → dynamic -
Invoked when a nonexistent method or property is accessed.
inherited
-
toString(
) → String -
A string representation of this object.
inherited
Operators
-
operator ==(
Object other) → bool -
The equality operator.
inherited
Constants
- endpointCount → const int
- endpointsByteLength → const int
- extendedByteLength → const int
- Where the extended data the transcoder does not use begins.
- headerBytes → const int
- selectorCount → const int
- selectorsByteLength → const int
- tablesByteLength → const int