Update basis_spec.txt

This commit is contained in:
Rich Geldreich
2020-05-26 00:55:05 -04:00
committed by GitHub
parent 7f98f715df
commit c5bbe545c8

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@@ -835,11 +835,13 @@ texture data, or it can immedately transcode the ETC1S data to another GPU textu
11.0 Alpha Channels in ETC1S Format Files
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If the ETC1S .basis file has an alpha channel, basis_file_header::m_flags will be logically OR's with
ETC1S .basis files can have optional alpha channels, stored in odd slices. If any slice needs an alpha channel,
all slices must have alpha channels. basis_file_header::m_flags will be logically OR's with
cBASISHeaderFlagHasAlphaSlices. Alpha channel ETC1S files will contain two slices for each mipmap level
(or face, or video frame, etc.). The even slices will contain the RGB data, and the odd slices will contain
the alpha data. A decoder can first decode the RGB data slice, then the next alpha channel slice, or it can
decode them in parallel using multithreading.
the alpha data, both stored in ETC1S format. A decoder can first decode the RGB data slice, then the next alpha
channel slice, or it can decode them in parallel using multithreading. The ETC1S green channel contains the
alpha values.
12.0 Texture Video
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