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- /* -----------------------------------------------------------------------------
- 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
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