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/**
* @file stbi_DDS_aug_c.h
* @brief DDS file support
*/
/// DDS file support, does decoding, _not_ direct uploading
/// (use SOIL for that ;-)
/// A bunch of DirectDraw Surface structures and flags
typedef struct {
unsigned int dwMagic;
unsigned int dwSize;
unsigned int dwFlags;
unsigned int dwHeight;
unsigned int dwWidth;
unsigned int dwPitchOrLinearSize;
unsigned int dwDepth;
unsigned int dwMipMapCount;
unsigned int dwReserved1[ 11 ];
// DDPIXELFORMAT
struct {
unsigned int dwSize;
unsigned int dwFlags;
unsigned int dwFourCC;
unsigned int dwRGBBitCount;
unsigned int dwRBitMask;
unsigned int dwGBitMask;
unsigned int dwBBitMask;
unsigned int dwAlphaBitMask;
} sPixelFormat;
// DDCAPS2
struct {
unsigned int dwCaps1;
unsigned int dwCaps2;
unsigned int dwDDSX;
unsigned int dwReserved;
} sCaps;
unsigned int dwReserved2;
} DDS_header ;
// the following constants were copied directly off the MSDN website
// The dwFlags member of the original DDSURFACEDESC2 structure
// can be set to one or more of the following values.
#define DDSD_CAPS 0x00000001
#define DDSD_HEIGHT 0x00000002
#define DDSD_WIDTH 0x00000004
#define DDSD_PITCH 0x00000008
#define DDSD_PIXELFORMAT 0x00001000
#define DDSD_MIPMAPCOUNT 0x00020000
#define DDSD_LINEARSIZE 0x00080000
#define DDSD_DEPTH 0x00800000
// DirectDraw Pixel Format
#define DDPF_ALPHAPIXELS 0x00000001
#define DDPF_FOURCC 0x00000004
#define DDPF_RGB 0x00000040
// The dwCaps1 member of the DDSCAPS2 structure can be
// set to one or more of the following values.
#define DDSCAPS_COMPLEX 0x00000008
#define DDSCAPS_TEXTURE 0x00001000
#define DDSCAPS_MIPMAP 0x00400000
// The dwCaps2 member of the DDSCAPS2 structure can be
// set to one or more of the following values.
#define DDSCAPS2_CUBEMAP 0x00000200
#define DDSCAPS2_CUBEMAP_POSITIVEX 0x00000400
#define DDSCAPS2_CUBEMAP_NEGATIVEX 0x00000800
#define DDSCAPS2_CUBEMAP_POSITIVEY 0x00001000
#define DDSCAPS2_CUBEMAP_NEGATIVEY 0x00002000
#define DDSCAPS2_CUBEMAP_POSITIVEZ 0x00004000
#define DDSCAPS2_CUBEMAP_NEGATIVEZ 0x00008000
#define DDSCAPS2_VOLUME 0x00200000
static int dds_test(stbi *s)
{
// check the magic number
if (get8(s) != 'D') return 0;
if (get8(s) != 'D') return 0;
if (get8(s) != 'S') return 0;
if (get8(s) != ' ') return 0;
// check header size
if (get32le(s) != 124) return 0;
return 1;
}
#ifndef STBI_NO_STDIO
int stbi_dds_test_file (FILE *f)
{
stbi s;
int r,n = ftell(f);
start_file(&s,f);
r = dds_test(&s);
fseek(f,n,SEEK_SET);
return r;
}
#endif
int stbi_dds_test_memory (stbi_uc const *buffer, int len)
{
stbi s;
start_mem(&s,buffer, len);
return dds_test(&s);
}
// helper functions
int stbi_convert_bit_range( int c, int from_bits, int to_bits )
{
int b = (1 << (from_bits - 1)) + c * ((1 << to_bits) - 1);
return (b + (b >> from_bits)) >> from_bits;
}
void stbi_rgb_888_from_565( unsigned int c, int *r, int *g, int *b )
{
*r = stbi_convert_bit_range( (c >> 11) & 31, 5, 8 );
*g = stbi_convert_bit_range( (c >> 05) & 63, 6, 8 );
*b = stbi_convert_bit_range( (c >> 00) & 31, 5, 8 );
}
void stbi_decode_DXT1_block(
unsigned char uncompressed[16*4],
unsigned char compressed[8] )
{
int next_bit = 4*8;
int i, r, g, b;
int c0, c1;
unsigned char decode_colors[4*4];
// find the 2 primary colors
c0 = compressed[0] + (compressed[1] << 8);
c1 = compressed[2] + (compressed[3] << 8);
stbi_rgb_888_from_565( c0, &r, &g, &b );
decode_colors[0] = r;
decode_colors[1] = g;
decode_colors[2] = b;
decode_colors[3] = 255;
stbi_rgb_888_from_565( c1, &r, &g, &b );
decode_colors[4] = r;
decode_colors[5] = g;
decode_colors[6] = b;
decode_colors[7] = 255;
if( c0 > c1 )
{
// no alpha, 2 interpolated colors
decode_colors[8] = (2*decode_colors[0] + decode_colors[4]) / 3;
decode_colors[9] = (2*decode_colors[1] + decode_colors[5]) / 3;
decode_colors[10] = (2*decode_colors[2] + decode_colors[6]) / 3;
decode_colors[11] = 255;
decode_colors[12] = (decode_colors[0] + 2*decode_colors[4]) / 3;
decode_colors[13] = (decode_colors[1] + 2*decode_colors[5]) / 3;
decode_colors[14] = (decode_colors[2] + 2*decode_colors[6]) / 3;
decode_colors[15] = 255;
} else
{
// 1 interpolated color, alpha
decode_colors[8] = (decode_colors[0] + decode_colors[4]) / 2;
decode_colors[9] = (decode_colors[1] + decode_colors[5]) / 2;
decode_colors[10] = (decode_colors[2] + decode_colors[6]) / 2;
decode_colors[11] = 255;
decode_colors[12] = 0;
decode_colors[13] = 0;
decode_colors[14] = 0;
decode_colors[15] = 0;
}
// decode the block
for( i = 0; i < 16*4; i += 4 )
{
int idx = ((compressed[next_bit>>3] >> (next_bit & 7)) & 3) * 4;
next_bit += 2;
uncompressed[i+0] = decode_colors[idx+0];
uncompressed[i+1] = decode_colors[idx+1];
uncompressed[i+2] = decode_colors[idx+2];
uncompressed[i+3] = decode_colors[idx+3];
}
// done
}
void stbi_decode_DXT23_alpha_block(
unsigned char uncompressed[16*4],
unsigned char compressed[8] )
{
int i, next_bit = 0;
// each alpha value gets 4 bits
for( i = 3; i < 16*4; i += 4 )
{
uncompressed[i] = stbi_convert_bit_range(
(compressed[next_bit>>3] >> (next_bit&7)) & 15,
4, 8 );
next_bit += 4;
}
}
void stbi_decode_DXT45_alpha_block(
unsigned char uncompressed[16*4],
unsigned char compressed[8] )
{
int i, next_bit = 8*2;
unsigned char decode_alpha[8];
// each alpha value gets 3 bits, and the 1st 2 bytes are the range
decode_alpha[0] = compressed[0];
decode_alpha[1] = compressed[1];
if( decode_alpha[0] > decode_alpha[1] )
{
// 6 step intermediate
decode_alpha[2] = (6*decode_alpha[0] + 1*decode_alpha[1]) / 7;
decode_alpha[3] = (5*decode_alpha[0] + 2*decode_alpha[1]) / 7;
decode_alpha[4] = (4*decode_alpha[0] + 3*decode_alpha[1]) / 7;
decode_alpha[5] = (3*decode_alpha[0] + 4*decode_alpha[1]) / 7;
decode_alpha[6] = (2*decode_alpha[0] + 5*decode_alpha[1]) / 7;
decode_alpha[7] = (1*decode_alpha[0] + 6*decode_alpha[1]) / 7;
} else
{
// 4 step intermediate, pluss full and none
decode_alpha[2] = (4*decode_alpha[0] + 1*decode_alpha[1]) / 5;
decode_alpha[3] = (3*decode_alpha[0] + 2*decode_alpha[1]) / 5;
decode_alpha[4] = (2*decode_alpha[0] + 3*decode_alpha[1]) / 5;
decode_alpha[5] = (1*decode_alpha[0] + 4*decode_alpha[1]) / 5;
decode_alpha[6] = 0;
decode_alpha[7] = 255;
}
for( i = 3; i < 16*4; i += 4 )
{
int idx = 0, bit;
bit = (compressed[next_bit>>3] >> (next_bit&7)) & 1;
idx += bit << 0;
++next_bit;
bit = (compressed[next_bit>>3] >> (next_bit&7)) & 1;
idx += bit << 1;
++next_bit;
bit = (compressed[next_bit>>3] >> (next_bit&7)) & 1;
idx += bit << 2;
++next_bit;
uncompressed[i] = decode_alpha[idx & 7];
}
// done
}
void stbi_decode_DXT_color_block(
unsigned char uncompressed[16*4],
unsigned char compressed[8] )
{
int next_bit = 4*8;
int i, r, g, b;
int c0, c1;
unsigned char decode_colors[4*3];
// find the 2 primary colors
c0 = compressed[0] + (compressed[1] << 8);
c1 = compressed[2] + (compressed[3] << 8);
stbi_rgb_888_from_565( c0, &r, &g, &b );
decode_colors[0] = r;
decode_colors[1] = g;
decode_colors[2] = b;
stbi_rgb_888_from_565( c1, &r, &g, &b );
decode_colors[3] = r;
decode_colors[4] = g;
decode_colors[5] = b;
// Like DXT1, but no choicees:
// no alpha, 2 interpolated colors
decode_colors[6] = (2*decode_colors[0] + decode_colors[3]) / 3;
decode_colors[7] = (2*decode_colors[1] + decode_colors[4]) / 3;
decode_colors[8] = (2*decode_colors[2] + decode_colors[5]) / 3;
decode_colors[9] = (decode_colors[0] + 2*decode_colors[3]) / 3;
decode_colors[10] = (decode_colors[1] + 2*decode_colors[4]) / 3;
decode_colors[11] = (decode_colors[2] + 2*decode_colors[5]) / 3;
// decode the block
for( i = 0; i < 16*4; i += 4 )
{
int idx = ((compressed[next_bit>>3] >> (next_bit & 7)) & 3) * 3;
next_bit += 2;
uncompressed[i+0] = decode_colors[idx+0];
uncompressed[i+1] = decode_colors[idx+1];
uncompressed[i+2] = decode_colors[idx+2];
}
// done
}
static stbi_uc *dds_load(stbi *s, int *x, int *y, int *comp, int req_comp)
{
// all variables go up front
stbi_uc *dds_data = NULL;
stbi_uc block[16*4];
stbi_uc compressed[8];
int flags, DXT_family;
int has_alpha, has_mipmap;
int is_compressed, cubemap_faces;
int block_pitch, num_blocks;
DDS_header header;
int i, sz, cf;
// load the header
if( sizeof( DDS_header ) != 128 )
{
return NULL;
}
getn( s, (stbi_uc*)(&header), 128 );
// and do some checking
if( header.dwMagic != (('D' << 0) | ('D' << 8) | ('S' << 16) | (' ' << 24)) ) return NULL;
if( header.dwSize != 124 ) return NULL;
flags = DDSD_CAPS | DDSD_HEIGHT | DDSD_WIDTH | DDSD_PIXELFORMAT;
if( (header.dwFlags & flags) != flags ) return NULL;
/* According to the MSDN spec, the dwFlags should contain
DDSD_LINEARSIZE if it's compressed, or DDSD_PITCH if
uncompressed. Some DDS writers do not conform to the
spec, so I need to make my reader more tolerant */
if( header.sPixelFormat.dwSize != 32 ) return NULL;
flags = DDPF_FOURCC | DDPF_RGB;
if( (header.sPixelFormat.dwFlags & flags) == 0 ) return NULL;
if( (header.sCaps.dwCaps1 & DDSCAPS_TEXTURE) == 0 ) return NULL;
// get the image data
s->img_x = header.dwWidth;
s->img_y = header.dwHeight;
s->img_n = 4;
is_compressed = (header.sPixelFormat.dwFlags & DDPF_FOURCC) / DDPF_FOURCC;
has_alpha = (header.sPixelFormat.dwFlags & DDPF_ALPHAPIXELS) / DDPF_ALPHAPIXELS;
has_mipmap = (header.sCaps.dwCaps1 & DDSCAPS_MIPMAP) && (header.dwMipMapCount > 1);
cubemap_faces = (header.sCaps.dwCaps2 & DDSCAPS2_CUBEMAP) / DDSCAPS2_CUBEMAP;
/* I need cubemaps to have square faces */
cubemap_faces &= (s->img_x == s->img_y);
cubemap_faces *= 5;
cubemap_faces += 1;
block_pitch = (s->img_x+3) >> 2;
num_blocks = block_pitch * ((s->img_y+3) >> 2);
/* let the user know what's going on */
*x = s->img_x;
*y = s->img_y;
*comp = s->img_n;
/* is this uncompressed? */
if( is_compressed )
{
/* compressed */
// note: header.sPixelFormat.dwFourCC is something like (('D'<<0)|('X'<<8)|('T'<<16)|('1'<<24))
DXT_family = 1 + (header.sPixelFormat.dwFourCC >> 24) - '1';
if( (DXT_family < 1) || (DXT_family > 5) ) return NULL;
/* check the expected size...oops, nevermind...
those non-compliant writers leave
dwPitchOrLinearSize == 0 */
// passed all the tests, get the RAM for decoding
sz = (s->img_x)*(s->img_y)*4*cubemap_faces;
dds_data = (unsigned char*)malloc( sz );
/* do this once for each face */
for( cf = 0; cf < cubemap_faces; ++ cf )
{
// now read and decode all the blocks
for( i = 0; i < num_blocks; ++i )
{
// where are we?
int bx, by, bw=4, bh=4;
int ref_x = 4 * (i % block_pitch);
int ref_y = 4 * (i / block_pitch);
// get the next block's worth of compressed data, and decompress it
if( DXT_family == 1 )
{
// DXT1
getn( s, compressed, 8 );
stbi_decode_DXT1_block( block, compressed );
} else if( DXT_family < 4 )
{
// DXT2/3
getn( s, compressed, 8 );
stbi_decode_DXT23_alpha_block ( block, compressed );
getn( s, compressed, 8 );
stbi_decode_DXT_color_block ( block, compressed );
} else
{
// DXT4/5
getn( s, compressed, 8 );
stbi_decode_DXT45_alpha_block ( block, compressed );
getn( s, compressed, 8 );
stbi_decode_DXT_color_block ( block, compressed );
}
// is this a partial block?
if( ref_x + 4 > (int)s->img_x )
{
bw = s->img_x - ref_x;
}
if( ref_y + 4 > (int)s->img_y )
{
bh = s->img_y - ref_y;
}
// now drop our decompressed data into the buffer
for( by = 0; by < bh; ++by )
{
int idx = 4*((ref_y+by+cf*s->img_x)*s->img_x + ref_x);
for( bx = 0; bx < bw*4; ++bx )
{
dds_data[idx+bx] = block[by*16+bx];
}
}
}
/* done reading and decoding the main image...
skip MIPmaps if present */
if( has_mipmap )
{
int block_size = 16;
if( DXT_family == 1 )
{
block_size = 8;
}
for( i = 1; i < (int)header.dwMipMapCount; ++i )
{
int mx = s->img_x >> (i + 2);
int my = s->img_y >> (i + 2);
if( mx < 1 )
{
mx = 1;
}
if( my < 1 )
{
my = 1;
}
skip( s, mx*my*block_size );
}
}
}/* per cubemap face */
} else
{
/* uncompressed */
DXT_family = 0;
s->img_n = 3;
if( has_alpha )
{
s->img_n = 4;
}
*comp = s->img_n;
sz = s->img_x*s->img_y*s->img_n*cubemap_faces;
dds_data = (unsigned char*)malloc( sz );
/* do this once for each face */
for( cf = 0; cf < cubemap_faces; ++ cf )
{
/* read the main image for this face */
getn( s, &dds_data[cf*s->img_x*s->img_y*s->img_n], s->img_x*s->img_y*s->img_n );
/* done reading and decoding the main image...
skip MIPmaps if present */
if( has_mipmap )
{
for( i = 1; i < (int)header.dwMipMapCount; ++i )
{
int mx = s->img_x >> i;
int my = s->img_y >> i;
if( mx < 1 )
{
mx = 1;
}
if( my < 1 )
{
my = 1;
}
skip( s, mx*my*s->img_n );
}
}
}
/* data was BGR, I need it RGB */
for( i = 0; i < sz; i += s->img_n )
{
unsigned char temp = dds_data[i];
dds_data[i] = dds_data[i+2];
dds_data[i+2] = temp;
}
}
/* finished decompressing into RGBA,
adjust the y size if we have a cubemap
note: sz is already up to date */
s->img_y *= cubemap_faces;
*y = s->img_y;
// did the user want something else, or
// see if all the alpha values are 255 (i.e. no transparency)
has_alpha = 0;
if( s->img_n == 4)
{
for( i = 3; (i < sz) && (has_alpha == 0); i += 4 )
{
has_alpha |= (dds_data[i] < 255);
}
}
if( (req_comp <= 4) && (req_comp >= 1) )
{
// user has some requirements, meet them
if( req_comp != s->img_n )
{
dds_data = convert_format( dds_data, s->img_n, req_comp, s->img_x, s->img_y );
*comp = s->img_n;
}
} else
{
// user had no requirements, only drop to RGB is no alpha
if( (has_alpha == 0) && (s->img_n == 4) )
{
dds_data = convert_format( dds_data, 4, 3, s->img_x, s->img_y );
*comp = 3;
}
}
// OK, done
return dds_data;
}
#ifndef STBI_NO_STDIO
stbi_uc *stbi_dds_load_from_file (FILE *f, int *x, int *y, int *comp, int req_comp)
{
stbi s;
start_file(&s,f);
return dds_load(&s,x,y,comp,req_comp);
}
stbi_uc *stbi_dds_load (char *filename, int *x, int *y, int *comp, int req_comp)
{
stbi_uc *data;
FILE *f = fopen(filename, "rb");
if (!f) return NULL;
data = stbi_dds_load_from_file(f,x,y,comp,req_comp);
fclose(f);
return data;
}
#endif
stbi_uc *stbi_dds_load_from_memory (stbi_uc const *buffer, int len, int *x, int *y, int *comp, int req_comp)
{
stbi s;
start_mem(&s,buffer, len);
return dds_load(&s,x,y,comp,req_comp);
}