void ClusterFit::SetColourSet( ColourSet const* colours, int flags )
{
ColourFit::SetColourSet( colours, flags );
// initialise the best error
#if SQUISH_USE_SIMD
m_besterror = VEC4_CONST( FLT_MAX );
Vec3 metric = m_metric.GetVec3();
#else
m_besterror = FLT_MAX;
Vec3 metric = m_metric;
#endif
// cache some values
int const count = m_colours->GetCount();
Vec3 const* values = m_colours->GetPoints();
// get the covariance matrix
Sym3x3 covariance = ComputeWeightedCovariance( count, values, m_colours->GetWeights(), metric );
// compute the principle component
Vec3 principle = ComputePrincipleComponent( covariance );
// build the list of values
float dps[16];
for( int i = 0; i < count; ++i )
{
dps[i] = Dot( values[i], principle );
m_order[i] = i;
}
// stable sort
for( int i = 0; i < count; ++i )
{
for( int j = i; j > 0 && dps[j] < dps[j - 1]; --j )
{
std::swap( dps[j], dps[j - 1] );
std::swap( m_order[j], m_order[j - 1] );
}
}
// weight all the points
#if SQUISH_USE_SIMD
Vec4 const* unweighted = m_colours->GetPointsSimd();
Vec4 const* weights = m_colours->GetWeightsSimd();
m_xxsum = VEC4_CONST( 0.0f );
#else
Vec3 const* unweighted = m_colours->GetPoints();
float const* weights = m_colours->GetWeights();
m_xxsum = Vec3( 0.0f );
#endif
for( int i = 0; i < count; ++i )
{
int p = m_order[i];
m_unweighted[i] = unweighted[p];
m_weights[i] = weights[p];
m_weighted[i] = weights[p]*unweighted[p];
m_xxsum += m_weighted[i]*m_weighted[i];
}
}
RangeFit::RangeFit( ColourSet const* colours, int flags, float* metric )
: ColourFit( colours, flags )
{
// initialise the metric (old perceptual = 0.2126f, 0.7152f, 0.0722f)
if( metric )
m_metric = Vec3( metric[0], metric[1], metric[2] );
else
m_metric = Vec3( 1.0f );
// initialise the best error
m_besterror = FLT_MAX;
// cache some values
int const count = m_colours->GetCount();
Vec3 const* values = m_colours->GetPoints();
float const* weights = m_colours->GetWeights();
// get the covariance matrix
Sym3x3 covariance = ComputeWeightedCovariance( count, values, weights );
// compute the principle component
Vec3 principle = ComputePrincipleComponent( covariance );
// get the min and max range as the codebook endpoints
Vec3 start( 0.0f );
Vec3 end( 0.0f );
if( count > 0 )
{
float min, max;
// compute the range
start = end = values[0];
min = max = Dot( values[0], principle );
for( int i = 1; i < count; ++i )
{
float val = Dot( values[i], principle );
if( val < min )
{
start = values[i];
min = val;
}
else if( val > max )
{
end = values[i];
max = val;
}
}
}
// clamp the output to [0, 1]
Vec3 const one( 1.0f );
Vec3 const zero( 0.0f );
start = Min( one, Max( zero, start ) );
end = Min( one, Max( zero, end ) );
// clamp to the grid and save
Vec3 const grid( 31.0f, 63.0f, 31.0f );
Vec3 const gridrcp( 1.0f/31.0f, 1.0f/63.0f, 1.0f/31.0f );
Vec3 const half( 0.5f );
m_start = Truncate( grid*start + half )*gridrcp;
m_end = Truncate( grid*end + half )*gridrcp;
}
