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Fixed the depth values in the doc file, made some info more clear

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WalterPlinge
2022-05-01 21:29:09 +01:00
parent df233aee94
commit 74d3bcec05
2 changed files with 11 additions and 10 deletions
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19
core/image/netpbm/doc.odin
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@@ -6,24 +6,25 @@ Formats:
PAM (P7 ): Portable Arbitrary Map, stores arbitrary channel images (1 or 2 bytes per value)
PFM (Pf, PF): Portable Float Map, stores floating-point images (Pf: 1 channel, PF: 3 channel)
Reading
Reading:
All formats fill out header fields `format`, `width`, `height`, `channels`, `depth`
Specific formats use more fields
PGM, PPM, and PAM set `maxval`
PAM also sets `tupltype`, and is able to set `channels` to an arbitrary value
PFM sets `scale` and `little_endian`
PGM, PPM, and PAM set `maxval` (maximum of 65535)
PAM sets `tupltype` if there is one, and can set `channels` to any value (not just 1 or 3)
PFM sets `scale` (float equivalent of `maxval`) and `little_endian` (endianness of stored floats)
Currently doesn't support reading multiple images from one binary-format file
Writing
Writing:
You can use your own `Netpbm_Info` struct to control how images are written
All formats require the header field `format` to be specified
Additional header fields are required for specific formats
PGM, PPM, and PAM require `maxval`
PGM, PPM, and PAM require `maxval` (maximum of 65535)
PAM also uses `tupltype`, though it may be left as default (empty or nil string)
PFM requires `scale` and `little_endian`, though the latter may be left untouched (default is false)
PFM requires `scale`, and optionally `little_endian`
Some syntax differences from the specifications:
`channels` stores what the PAM specification calls `depth`
`depth` instead stores how many bytes will fit `maxval` (should only be 1, 2, or 4)
`channels` stores the number of values per pixel, what the PAM specification calls `depth`
`depth` instead is the number of bits for a single value (32 for PFM, 16 or 8 otherwise)
`scale` and `little_endian` are separated, so the `header` will always store a positive `scale`
`little_endian` will only be true for a negative `scale` PFM, every other format will be false
`little_endian` only describes the netpbm data being read/written, the image buffer will be native

2
core/image/netpbm/netpbm.odin
View File

@@ -109,7 +109,7 @@ save_to_buffer :: proc(img: ^Image, custom_info: Info = {}, allocator := context
// using info so we can just talk about the header
using info
//? validation
// validation
if header.format in (PBM + PGM + Formats{.Pf}) && img.channels != 1 \
|| header.format in (PPM + Formats{.PF}) && img.channels != 3 {
err = .Invalid_Number_Of_Channels