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tex.h File Reference
#include "lib/res/handle.h"
#include "lib/os_path.h"
#include "lib/file/vfs/vfs_path.h"
#include "lib/allocators/dynarray.h"
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Classes

struct  Tex
 stores all data describing an image. More...
 

Namespaces

 ERR
 

Introduction


 
 WARN
 
 INFO
 

Typedefs

typedef void(* MipmapCB) (size_t level, size_t level_w, size_t level_h, const u8 *RESTRICT level_data, size_t level_data_size, void *RESTRICT cbData)
 callback function for each mipmap level. More...
 

Enumerations

enum  TexFlags {
  TEX_DXT = 0x7, DXT1A = 7, TEX_BGR = 0x08, TEX_ALPHA = 0x10,
  TEX_GREY = 0x20, TEX_BOTTOM_UP = 0x40, TEX_TOP_DOWN = 0x80, TEX_ORIENTATION = TEX_BOTTOM_UP|TEX_TOP_DOWN,
  TEX_MIPMAPS = 0x100, TEX_UNDEFINED_FLAGS = ~0x1FF
}
 flags describing the pixel format. More...
 

Functions

void tex_set_global_orientation (int orientation)
 Set the orientation to which all loaded images will automatically be converted (excepting file formats that don't specify their orientation, i.e. More...
 
void tex_util_foreach_mipmap (size_t w, size_t h, size_t bpp, const u8 *data, int levels_to_skip, size_t data_padding, MipmapCB cb, void *RESTRICT cbData)
 for a series of mipmaps stored from base to highest, call back for each level. More...
 
bool tex_is_known_extension (const VfsPath &pathname)
 Is the file's extension that of a texture format supported by tex_load? More...
 
size_t tex_hdr_size (const VfsPath &filename)
 return the minimum header size (i.e. More...
 

Variables

const Status ERR::TEX_UNKNOWN_FORMAT = -120100
 
const Status ERR::TEX_INCOMPLETE_HEADER = -120101
 
const Status ERR::TEX_FMT_INVALID = -120102
 
const Status ERR::TEX_INVALID_COLOR_TYPE = -120103
 
const Status ERR::TEX_NOT_8BIT_PRECISION = -120104
 
const Status ERR::TEX_INVALID_LAYOUT = -120105
 
const Status ERR::TEX_COMPRESSED = -120106
 
const Status ERR::TEX_INVALID_SIZE = -120107
 
const Status WARN::TEX_INVALID_DATA = +120108
 
const Status INFO::TEX_CODEC_CANNOT_HANDLE = +120109
 
const int TEX_BASE_LEVEL_ONLY = -1
 special value for levels_to_skip: the callback will only be called for the base mipmap level (i.e. More...
 

Typedef Documentation

typedef void(* MipmapCB) (size_t level, size_t level_w, size_t level_h, const u8 *RESTRICT level_data, size_t level_data_size, void *RESTRICT cbData)

callback function for each mipmap level.

Parameters
levelnumber; 0 for base level (i.e. 100%), or the first one in case some were skipped.
level_w,level_hpixel dimensions (powers of 2, never 0)
level_datathe level's texels
level_data_size[bytes]
cbDatapassed through from tex_util_foreach_mipmap.

Enumeration Type Documentation

enum TexFlags

flags describing the pixel format.

these are to be interpreted as deviations from "plain" format, i.e. uncompressed RGB.

Enumerator
TEX_DXT 

flags & TEX_DXT is a field indicating compression.

if 0, the texture is uncompressed; otherwise, it holds the S3TC type: 1,3,5 or DXT1A. not converted by default - glCompressedTexImage2D receives the compressed data.

DXT1A 

we need a special value for DXT1a to avoid having to consider flags & TEX_ALPHA to determine S3TC type.

the value is arbitrary; do not rely on it!

TEX_BGR 

indicates B and R pixel components are exchanged.

depending on flags & TEX_ALPHA or bpp, this means either BGR or BGRA. not converted by default - it's an acceptable format for OpenGL.

TEX_ALPHA 

indicates the image contains an alpha channel.

this is set for your convenience - there are many formats containing alpha and divining this information from them is hard. (conversion is not applicable here)

TEX_GREY 

indicates the image is 8bpp greyscale.

this is required to differentiate between alpha-only and intensity formats. not converted by default - it's an acceptable format for OpenGL.

TEX_BOTTOM_UP 

flags & TEX_ORIENTATION is a field indicating orientation, i.e.

in what order the pixel rows are stored.

tex_load always sets this to the global orientation (and flips the image accordingly to match). texture codecs may in intermediate steps during loading set this to 0 if they don't know which way around they are (e.g. DDS), or to whatever their file contains.

TEX_TOP_DOWN 
TEX_ORIENTATION 
TEX_MIPMAPS 

mask

indicates the image data includes mipmaps. they are stored from lowest to highest (1x1), one after the other. (conversion is not applicable here)

TEX_UNDEFINED_FLAGS 

Function Documentation

size_t tex_hdr_size ( const VfsPath filename)

return the minimum header size (i.e.

offset to pixel data) of the file format corresponding to the filename.

rationale: this can be used to optimize calls to tex_write: when allocating the buffer that will hold the image, allocate this much extra and pass the pointer as base+hdr_size. this allows writing the header directly into the output buffer and makes for zero-copy IO.

Parameters
filenameFilename; only the extension (that after '.') is used. case-insensitive.
Returns
size [bytes] or 0 on error (i.e. no codec found).
bool tex_is_known_extension ( const VfsPath pathname)

Is the file's extension that of a texture format supported by tex_load?

Rationale: tex_load complains if the given file is of an unsupported type. this API allows users to preempt that warning (by checking the filename themselves), and also provides for e.g. enumerating only images in a file picker. an alternative might be a flag to suppress warning about invalid files, but this is open to misuse.

Parameters
pathnameOnly the extension (starting with '.') is used. case-insensitive.
Returns
bool
void tex_set_global_orientation ( int  orientation)

Set the orientation to which all loaded images will automatically be converted (excepting file formats that don't specify their orientation, i.e.

DDS). See "Default Orientation" in docs.

Parameters
orientationEither TEX_BOTTOM_UP or TEX_TOP_DOWN.
void tex_util_foreach_mipmap ( size_t  w,
size_t  h,
size_t  bpp,
const u8 data,
int  levels_to_skip,
size_t  data_padding,
MipmapCB  cb,
void *RESTRICT  cbData 
)

for a series of mipmaps stored from base to highest, call back for each level.

Parameters
w,hPixel dimensions.
bppBits per pixel.
dataSeries of mipmaps.
levels_to_skipNumber of levels (counting from base) to skip, or TEX_BASE_LEVEL_ONLY to only call back for the base image. Rationale: this avoids needing to special case for images with or without mipmaps.
data_paddingMinimum pixel dimensions of mipmap levels. This is used in S3TC images, where each level is actually stored in 4x4 blocks. usually 1 to indicate levels are consecutive.
cbMipmapCB to call.
cbDataExtra data to pass to cb.

Variable Documentation

const int TEX_BASE_LEVEL_ONLY = -1

special value for levels_to_skip: the callback will only be called for the base mipmap level (i.e.

100%)