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Diffstat (limited to 'thirdparty/squish/colourblock.cpp')
| -rw-r--r-- | thirdparty/squish/colourblock.cpp | 214 |
1 files changed, 214 insertions, 0 deletions
diff --git a/thirdparty/squish/colourblock.cpp b/thirdparty/squish/colourblock.cpp new file mode 100644 index 0000000000..af8b980365 --- /dev/null +++ b/thirdparty/squish/colourblock.cpp @@ -0,0 +1,214 @@ +/* ----------------------------------------------------------------------------- + + Copyright (c) 2006 Simon Brown si@sjbrown.co.uk + + Permission is hereby granted, free of charge, to any person obtaining + a copy of this software and associated documentation files (the + "Software"), to deal in the Software without restriction, including + without limitation the rights to use, copy, modify, merge, publish, + distribute, sublicense, and/or sell copies of the Software, and to + permit persons to whom the Software is furnished to do so, subject to + the following conditions: + + The above copyright notice and this permission notice shall be included + in all copies or substantial portions of the Software. + + THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS + OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF + MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. + IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY + CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, + TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE + SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. + + -------------------------------------------------------------------------- */ + +#include "colourblock.h" + +namespace squish { + +static int FloatToInt( float a, int limit ) +{ + // use ANSI round-to-zero behaviour to get round-to-nearest + int i = ( int )( a + 0.5f ); + + // clamp to the limit + if( i < 0 ) + i = 0; + else if( i > limit ) + i = limit; + + // done + return i; +} + +static int FloatTo565( Vec3::Arg colour ) +{ + // get the components in the correct range + int r = FloatToInt( 31.0f*colour.X(), 31 ); + int g = FloatToInt( 63.0f*colour.Y(), 63 ); + int b = FloatToInt( 31.0f*colour.Z(), 31 ); + + // pack into a single value + return ( r << 11 ) | ( g << 5 ) | b; +} + +static void WriteColourBlock( int a, int b, u8* indices, void* block ) +{ + // get the block as bytes + u8* bytes = ( u8* )block; + + // write the endpoints + bytes[0] = ( u8 )( a & 0xff ); + bytes[1] = ( u8 )( a >> 8 ); + bytes[2] = ( u8 )( b & 0xff ); + bytes[3] = ( u8 )( b >> 8 ); + + // write the indices + for( int i = 0; i < 4; ++i ) + { + u8 const* ind = indices + 4*i; + bytes[4 + i] = ind[0] | ( ind[1] << 2 ) | ( ind[2] << 4 ) | ( ind[3] << 6 ); + } +} + +void WriteColourBlock3( Vec3::Arg start, Vec3::Arg end, u8 const* indices, void* block ) +{ + // get the packed values + int a = FloatTo565( start ); + int b = FloatTo565( end ); + + // remap the indices + u8 remapped[16]; + if( a <= b ) + { + // use the indices directly + for( int i = 0; i < 16; ++i ) + remapped[i] = indices[i]; + } + else + { + // swap a and b + std::swap( a, b ); + for( int i = 0; i < 16; ++i ) + { + if( indices[i] == 0 ) + remapped[i] = 1; + else if( indices[i] == 1 ) + remapped[i] = 0; + else + remapped[i] = indices[i]; + } + } + + // write the block + WriteColourBlock( a, b, remapped, block ); +} + +void WriteColourBlock4( Vec3::Arg start, Vec3::Arg end, u8 const* indices, void* block ) +{ + // get the packed values + int a = FloatTo565( start ); + int b = FloatTo565( end ); + + // remap the indices + u8 remapped[16]; + if( a < b ) + { + // swap a and b + std::swap( a, b ); + for( int i = 0; i < 16; ++i ) + remapped[i] = ( indices[i] ^ 0x1 ) & 0x3; + } + else if( a == b ) + { + // use index 0 + for( int i = 0; i < 16; ++i ) + remapped[i] = 0; + } + else + { + // use the indices directly + for( int i = 0; i < 16; ++i ) + remapped[i] = indices[i]; + } + + // write the block + WriteColourBlock( a, b, remapped, block ); +} + +static int Unpack565( u8 const* packed, u8* colour ) +{ + // build the packed value + int value = ( int )packed[0] | ( ( int )packed[1] << 8 ); + + // get the components in the stored range + u8 red = ( u8 )( ( value >> 11 ) & 0x1f ); + u8 green = ( u8 )( ( value >> 5 ) & 0x3f ); + u8 blue = ( u8 )( value & 0x1f ); + + // scale up to 8 bits + colour[0] = ( red << 3 ) | ( red >> 2 ); + colour[1] = ( green << 2 ) | ( green >> 4 ); + colour[2] = ( blue << 3 ) | ( blue >> 2 ); + colour[3] = 255; + + // return the value + return value; +} + +void DecompressColour( u8* rgba, void const* block, bool isDxt1 ) +{ + // get the block bytes + u8 const* bytes = reinterpret_cast< u8 const* >( block ); + + // unpack the endpoints + u8 codes[16]; + int a = Unpack565( bytes, codes ); + int b = Unpack565( bytes + 2, codes + 4 ); + + // generate the midpoints + for( int i = 0; i < 3; ++i ) + { + int c = codes[i]; + int d = codes[4 + i]; + + if( isDxt1 && a <= b ) + { + codes[8 + i] = ( u8 )( ( c + d )/2 ); + codes[12 + i] = 0; + } + else + { + codes[8 + i] = ( u8 )( ( 2*c + d )/3 ); + codes[12 + i] = ( u8 )( ( c + 2*d )/3 ); + } + } + + // fill in alpha for the intermediate values + codes[8 + 3] = 255; + codes[12 + 3] = ( isDxt1 && a <= b ) ? 0 : 255; + + // unpack the indices + u8 indices[16]; + for( int i = 0; i < 4; ++i ) + { + u8* ind = indices + 4*i; + u8 packed = bytes[4 + i]; + + ind[0] = packed & 0x3; + ind[1] = ( packed >> 2 ) & 0x3; + ind[2] = ( packed >> 4 ) & 0x3; + ind[3] = ( packed >> 6 ) & 0x3; + } + + // store out the colours + for( int i = 0; i < 16; ++i ) + { + u8 offset = 4*indices[i]; + for( int j = 0; j < 4; ++j ) + rgba[4*i + j] = codes[offset + j]; + } +} + +} // namespace squish |