public ClusterFit(ColourSet colours, SquishFlags flags)
: base(colours, flags)
{
// set the iteration count
m_iterationCount = ((m_flags & SquishFlags.ColourIterativeClusterFit) != 0) ? kMaxIterations : 1;
// initialise the best error
m_besterror = new Vec4(float.MaxValue);
// initialise the metric
bool perceptual = ((m_flags & SquishFlags.ColourMetricPerceptual) != 0);
if (perceptual)
m_metric = new Vec4(0.2126f, 0.7152f, 0.0722f, 0.0f);
else
m_metric = new Vec4(1.0f);
// cache some values
int count = m_colours.GetCount();
Vec3[] values = m_colours.GetPoints();
// get the covariance matrix
Sym3x3 covariance = Sym3x3.ComputeWeightedCovariance(count, values, m_colours.GetWeights());
// compute the principle component
m_principle = Sym3x3.ComputePrincipleComponent(covariance);
}
public static unsafe void WriteColourBlock4(Vec3 start, Vec3 end, byte* indices, byte* block)
{
// get the packed values
int a = FloatTo565(start);
int b = FloatTo565(end);
// remap the indices
byte[] remapped = new byte[16];
if (a < b)
{
// swap a and b
CMath.Swap<int>(ref a, ref b);
for (int i = 0; i < 16; ++i)
remapped[i] = (byte)((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];
}
fixed (byte* fixRemapped = remapped)
{
// write the block
WriteColourBlock(a, b, fixRemapped, block);
}
}
public static Vec3 Truncate( Vec3 v )
{
return new Vec3(
v.X() > 0.0f ? CMath.Floor( v.X() ) : CMath.Ceil( v.X() ),
v.Y() > 0.0f ? CMath.Floor( v.Y() ) : CMath.Ceil( v.Y() ),
v.Z() > 0.0f ? CMath.Floor(v.Z()) : CMath.Ceil(v.Z())
);
}
public static Vec3 Max(Vec3 a, Vec3 b)
{
return new Vec3(
Math.Max(a.X(), b.X()),
Math.Max(a.Y(), b.Y()),
Math.Max(a.Z(), b.Z())
);
}
public static int FloatTo565(Vec3 colour)
{
// get the components in the correct range
int r = CMath.FloatToInt(31.0f * colour.X(), 31);
int g = CMath.FloatToInt(63.0f * colour.Y(), 63);
int b = CMath.FloatToInt(31.0f * colour.Z(), 31);
// pack into a single value
return (r << 11) | (g << 5) | b;
}
private bool ConstructOrdering(Vec3 axis, int iteration)
{
// cache some values
int count = m_colours.GetCount();
Vec3[] values = m_colours.GetPoints();
// build the list of dot products
float[] dps = new float[16];
int orderIndex = 16 * iteration;
for (int i = 0; i < count; ++i)
{
dps[i] = Vec3.Dot(values[i], axis);
m_order[orderIndex + i] = (byte)i;
}
// stable sort using them
for (int i = 0; i < count; ++i)
{
for (int j = i; j > 0 && dps[j] < dps[j - 1]; --j)
{
CMath.Swap<float>(ref dps[j], ref dps[j - 1]);
CMath.Swap<byte>(ref m_order[orderIndex + j], ref m_order[orderIndex + (j - 1)]);
}
}
// check this ordering is unique
for (int it = 0; it < iteration; ++it)
{
int prevIndex = 16 * it;
bool same = true;
for (int i = 0; i < count; ++i)
{
if (m_order[orderIndex + i] != m_order[prevIndex + i])
{
same = false;
break;
}
}
if (same)
return false;
}
// copy the ordering and weight all the points
Vec3[] unweighted = m_colours.GetPoints();
float[] weights = m_colours.GetWeights();
m_xsum_wsum = new Vec4(0.0f);
for (int i = 0; i < count; ++i)
{
int j = m_order[orderIndex + i];
Vec4 p = new Vec4(unweighted[j].X(), unweighted[j].Y(), unweighted[j].Z(), 1.0f);
Vec4 w = new Vec4(weights[j]);
Vec4 x = p * w;
m_points_weights[i] = x;
m_xsum_wsum += x;
}
return true;
}
protected override unsafe void Compress3(byte* block)
{
// cache some values
int count = m_colours.GetCount();
Vec3[] values = m_colours.GetPoints();
// create a codebook
Vec3[] codes = new Vec3[3];
codes[0] = m_start;
codes[1] = m_end;
codes[2] = 0.5f * m_start + 0.5f * m_end;
// match each point to the closest code
byte[] closest = new byte[16];
float error = 0.0f;
for (int i = 0; i < count; ++i)
{
// find the closest code
float dist = float.MaxValue;
int idx = 0;
for (int j = 0; j < 3; ++j)
{
float d = Vec3.LengthSquared(m_metric * (values[i] - codes[j]));
if (d < dist)
{
dist = d;
idx = j;
}
}
// save the index
closest[i] = (byte)idx;
// accumulate the error
error += dist;
}
// save this scheme if it wins
if( error < m_besterror )
{
// remap the indices
byte[] indices = new byte[16];
fixed (byte* fixClosest = closest, fixIndices = indices)
{
m_colours.RemapIndices(fixClosest, fixIndices);
// save the block
ColourBlock.WriteColourBlock3(m_start, m_end, fixIndices, block);
}
// save the error
m_besterror = error;
}
}
public RangeFit(ColourSet colours, SquishFlags flags)
: base(colours, flags)
{
// initialise the metric
bool perceptual = ((m_flags & SquishFlags.ColourMetricPerceptual) != 0);
if (perceptual)
m_metric = new Vec3(0.2126f, 0.7152f, 0.0722f);
else
m_metric = new Vec3(1.0f);
// initialise the best error
m_besterror = float.MaxValue;
// cache some values
int count = m_colours.GetCount();
Vec3[] values = m_colours.GetPoints();
float[] weights = m_colours.GetWeights();
// get the covariance matrix
Sym3x3 covariance = Sym3x3.ComputeWeightedCovariance(count, values, weights);
// compute the principle component
Vec3 principle = Sym3x3.ComputePrincipleComponent(covariance);
// get the min and max range as the codebook endpoints
Vec3 start = new Vec3(0.0f);
Vec3 end = new Vec3(0.0f);
if (count > 0)
{
float min, max;
// compute the range
start = end = values[0];
min = max = Vec3.Dot(values[0], principle);
for (int i = 1; i < count; ++i)
{
float val = Vec3.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 one = new Vec3(1.0f);
Vec3 zero = new Vec3(0.0f);
start = Vec3.Min(one, Vec3.Max(zero, start));
end = Vec3.Min(one, Vec3.Max(zero, end));
// clamp to the grid and save
Vec3 grid = new Vec3(31.0f, 63.0f, 31.0f);
Vec3 gridrcp = new Vec3(1.0f / 31.0f, 1.0f / 63.0f, 1.0f / 31.0f);
Vec3 half = new Vec3(0.5f);
m_start = Vec3.Truncate(grid * start + half) * gridrcp;
m_end = Vec3.Truncate(grid * end + half) * gridrcp;
}
private void ComputeEndPoints(SingleColourLookup[][] lookups)
{
// check each index combination (endpoint or intermediate)
m_error = int.MaxValue;
for (int index = 0; index < 2; ++index)
{
// check the error for this codebook index
SourceBlock[] sources = new SourceBlock[3];
int error = 0;
for( int channel = 0; channel < 3; ++channel )
{
// grab the lookup table and index for this channel
SingleColourLookup[] lookup = lookups[channel];
int target = m_colour[channel];
// store a pointer to the source for this channel
sources[channel] = lookup[target].sources[index]/* + index*/;
// accumulate the error
int diff = sources[channel].error;
error += diff * diff;
}
// keep it if the error is lower
if (error < m_error)
{
m_start = new Vec3(
(float)sources[0].start / 31.0f,
(float)sources[1].start / 63.0f,
(float)sources[2].start / 31.0f
);
m_end = new Vec3(
(float)sources[0].end / 31.0f,
(float)sources[1].end / 63.0f,
(float)sources[2].end / 31.0f
);
m_index = (byte)(2 * index);
m_error = error;
}
}
}
public static float LengthSquared(Vec3 v)
{
return Dot(v, v);
}
public static float Dot(Vec3 a, Vec3 b)
{
return a.X() * b.X() + a.Y()* b.Y() + a.Z() * b.Z();
}
public static Sym3x3 ComputeWeightedCovariance(int n, Vec3[] points, float[] weights)
{
// compute the centroid
float total = 0.0f;
Vec3 centroid = new Vec3(0.0f);
for (int i = 0; i < n; ++i)
{
total += weights[i];
centroid += weights[i] * points[i];
}
centroid /= total;
// accumulate the covariance matrix
Sym3x3 covariance = new Sym3x3(0.0f);
for (int i = 0; i < n; ++i)
{
Vec3 a = points[i] - centroid;
Vec3 b = weights[i] * a;
covariance[0] += a.X() * b.X();
covariance[1] += a.X() * b.Y();
covariance[2] += a.X() * b.Z();
covariance[3] += a.Y() * b.Y();
covariance[4] += a.Y() * b.Z();
covariance[5] += a.Z() * b.Z();
}
// return it
return covariance;
}
public unsafe ColourSet(byte* rgba, int mask, SquishFlags flags)
{
m_count = 0;
m_transparent = false;
bool isDxt1 = ((flags & SquishFlags.Dxt1) != 0);
bool weightByAlpha = ((flags & SquishFlags.WeightColourByAlpha) != 0);
// create the minimal set
for (int i = 0; i < 16; ++i)
{
// check this pixel is enabled
int bit = 1 << i;
if ((mask & bit) == 0)
{
m_remap[i] = -1;
continue;
}
// check for transparent pixels when using dxt1
if (isDxt1 && rgba[4 * i + 3] < 128)
{
m_remap[i] = -1;
m_transparent = true;
continue;
}
// loop over previous points for a match
for (int j = 0; ; ++j)
{
// allocate a new point
if (j == i)
{
// normalise coordinates to [0,1]
float x = (float)rgba[4 * i] / 255.0f;
float y = (float)rgba[4 * i + 1] / 255.0f;
float z = (float)rgba[4 * i + 2] / 255.0f;
// ensure there is always non-zero weight even for zero alpha
float w = (float)(rgba[4 * i + 3] + 1) / 256.0f;
// add the point
m_points[m_count] = new Vec3(x, y, z);
m_weights[m_count] = (weightByAlpha ? w : 1.0f);
m_remap[i] = m_count;
// advance
++m_count;
break;
}
// check for a match
int oldbit = 1 << j;
bool match = ((mask & oldbit) != 0)
&& (rgba[4 * i] == rgba[4 * j])
&& (rgba[4 * i + 1] == rgba[4 * j + 1])
&& (rgba[4 * i + 2] == rgba[4 * j + 2])
&& (rgba[4 * j + 3] >= 128 || !isDxt1);
if (match)
{
// get the index of the match
int index = m_remap[j];
// ensure there is always non-zero weight even for zero alpha
float w = (float)(rgba[4 * i + 3] + 1) / 256.0f;
// map to this point and increase the weight
m_weights[index] += (weightByAlpha ? w : 1.0f);
m_remap[i] = index;
break;
}
}
}
// square root the weights
for (int i = 0; i < m_count; ++i)
m_weights[i] = CMath.Sqrt(m_weights[i]);
}
