All squish API functions live in this namespace. More...
Typedefs | |
typedef unsigned char | u8 |
Typedef a quantity that is a single unsigned byte. | |
Enumerations | |
enum | { kDxt1 = ( 1 << 0 ), kDxt3 = ( 1 << 1 ), kDxt5 = ( 1 << 2 ), kColourIterativeClusterFit = ( 1 << 8 ), kColourClusterFit = ( 1 << 3 ), kColourRangeFit = ( 1 << 4 ), kColourMetricPerceptual = ( 1 << 5 ), kColourMetricUniform = ( 1 << 6 ), kWeightColourByAlpha = ( 1 << 7 ) } |
Functions | |
void | Compress (u8 const *rgba, void *block, int flags) |
Compresses a 4x4 block of pixels. | |
void | CompressMasked (u8 const *rgba, int mask, void *block, int flags) |
Compresses a 4x4 block of pixels. | |
void | Decompress (u8 *rgba, void const *block, int flags) |
Decompresses a 4x4 block of pixels. | |
int | GetStorageRequirements (int width, int height, int flags) |
Computes the amount of compressed storage required. | |
void | CompressImage (u8 const *rgba, int width, int height, void *blocks, int flags) |
Compresses an image in memory. | |
void | DecompressImage (u8 *rgba, int width, int height, void const *blocks, int flags) |
Decompresses an image in memory. |
All squish API functions live in this namespace.
typedef unsigned char squish::u8 |
Typedef a quantity that is a single unsigned byte.
anonymous enum |
void squish::Compress | ( | u8 const * | rgba, | |
void * | block, | |||
int | flags | |||
) |
Compresses a 4x4 block of pixels.
rgba | The rgba values of the 16 source pixels. | |
block | Storage for the compressed DXT block. | |
flags | Compression flags. |
The source pixels should be presented as a contiguous array of 16 rgba values, with each component as 1 byte each. In memory this should be:
{ r1, g1, b1, a1, .... , r16, g16, b16, a16 }
The flags parameter should specify either kDxt1, kDxt3 or kDxt5 compression, however, DXT1 will be used by default if none is specified. When using DXT1 compression, 8 bytes of storage are required for the compressed DXT block. DXT3 and DXT5 compression require 16 bytes of storage per block.
The flags parameter can also specify a preferred colour compressor and colour error metric to use when fitting the RGB components of the data. Possible colour compressors are: kColourClusterFit (the default), kColourRangeFit or kColourIterativeClusterFit. Possible colour error metrics are: kColourMetricPerceptual (the default) or kColourMetricUniform. If no flags are specified in any particular category then the default will be used. Unknown flags are ignored.
When using kColourClusterFit, an additional flag can be specified to weight the colour of each pixel by its alpha value. For images that are rendered using alpha blending, this can significantly increase the perceived quality.
void squish::CompressImage | ( | u8 const * | rgba, | |
int | width, | |||
int | height, | |||
void * | blocks, | |||
int | flags | |||
) |
Compresses an image in memory.
rgba | The pixels of the source. | |
width | The width of the source image. | |
height | The height of the source image. | |
blocks | Storage for the compressed output. | |
flags | Compression flags. |
The source pixels should be presented as a contiguous array of width*height rgba values, with each component as 1 byte each. In memory this should be:
{ r1, g1, b1, a1, .... , rn, gn, bn, an } for n = width*height
The flags parameter should specify either kDxt1, kDxt3 or kDxt5 compression, however, DXT1 will be used by default if none is specified. When using DXT1 compression, 8 bytes of storage are required for each compressed DXT block. DXT3 and DXT5 compression require 16 bytes of storage per block.
The flags parameter can also specify a preferred colour compressor and colour error metric to use when fitting the RGB components of the data. Possible colour compressors are: kColourClusterFit (the default), kColourRangeFit or kColourIterativeClusterFit. Possible colour error metrics are: kColourMetricPerceptual (the default) or kColourMetricUniform. If no flags are specified in any particular category then the default will be used. Unknown flags are ignored.
When using kColourClusterFit, an additional flag can be specified to weight the colour of each pixel by its alpha value. For images that are rendered using alpha blending, this can significantly increase the perceived quality.
Internally this function calls squish::Compress for each block. To see how much memory is required in the compressed image, use squish::GetStorageRequirements.
void squish::CompressMasked | ( | u8 const * | rgba, | |
int | mask, | |||
void * | block, | |||
int | flags | |||
) |
Compresses a 4x4 block of pixels.
rgba | The rgba values of the 16 source pixels. | |
mask | The valid pixel mask. | |
block | Storage for the compressed DXT block. | |
flags | Compression flags. |
The source pixels should be presented as a contiguous array of 16 rgba values, with each component as 1 byte each. In memory this should be:
{ r1, g1, b1, a1, .... , r16, g16, b16, a16 }
The mask parameter enables only certain pixels within the block. The lowest bit enables the first pixel and so on up to the 16th bit. Bits beyond the 16th bit are ignored. Pixels that are not enabled are allowed to take arbitrary colours in the output block. An example of how this can be used is in the CompressImage function to disable pixels outside the bounds of the image when the width or height is not divisible by 4.
The flags parameter should specify either kDxt1, kDxt3 or kDxt5 compression, however, DXT1 will be used by default if none is specified. When using DXT1 compression, 8 bytes of storage are required for the compressed DXT block. DXT3 and DXT5 compression require 16 bytes of storage per block.
The flags parameter can also specify a preferred colour compressor and colour error metric to use when fitting the RGB components of the data. Possible colour compressors are: kColourClusterFit (the default), kColourRangeFit or kColourIterativeClusterFit. Possible colour error metrics are: kColourMetricPerceptual (the default) or kColourMetricUniform. If no flags are specified in any particular category then the default will be used. Unknown flags are ignored.
When using kColourClusterFit, an additional flag can be specified to weight the colour of each pixel by its alpha value. For images that are rendered using alpha blending, this can significantly increase the perceived quality.
void squish::Decompress | ( | u8 * | rgba, | |
void const * | block, | |||
int | flags | |||
) |
Decompresses a 4x4 block of pixels.
rgba | Storage for the 16 decompressed pixels. | |
block | The compressed DXT block. | |
flags | Compression flags. |
The decompressed pixels will be written as a contiguous array of 16 rgba values, with each component as 1 byte each. In memory this is:
{ r1, g1, b1, a1, .... , r16, g16, b16, a16 }
The flags parameter should specify either kDxt1, kDxt3 or kDxt5 compression, however, DXT1 will be used by default if none is specified. All other flags are ignored.
void squish::DecompressImage | ( | u8 * | rgba, | |
int | width, | |||
int | height, | |||
void const * | blocks, | |||
int | flags | |||
) |
Decompresses an image in memory.
rgba | Storage for the decompressed pixels. | |
width | The width of the source image. | |
height | The height of the source image. | |
blocks | The compressed DXT blocks. | |
flags | Compression flags. |
The decompressed pixels will be written as a contiguous array of width*height 16 rgba values, with each component as 1 byte each. In memory this is:
{ r1, g1, b1, a1, .... , rn, gn, bn, an } for n = width*height
The flags parameter should specify either kDxt1, kDxt3 or kDxt5 compression, however, DXT1 will be used by default if none is specified. All other flags are ignored.
Internally this function calls squish::Decompress for each block.
int squish::GetStorageRequirements | ( | int | width, | |
int | height, | |||
int | flags | |||
) |
Computes the amount of compressed storage required.
width | The width of the image. | |
height | The height of the image. | |
flags | Compression flags. |
The flags parameter should specify either kDxt1, kDxt3 or kDxt5 compression, however, DXT1 will be used by default if none is specified. All other flags are ignored.
Most DXT images will be a multiple of 4 in each dimension, but this function supports arbitrary size images by allowing the outer blocks to be only partially used.