// maxColor and minColor are expected to be in the same range as the color set.
static uint computeIndices3(ColorSet set, Vector3 maxColor, Vector3 minColor)
{
Vector3[] palette = new Vector3[4];
palette[0] = minColor;
palette[1] = maxColor;
palette[2] = (palette[0] + palette[1]) * 0.5f;
uint indices = 0;
for (uint i = 0; i < 16; i++)
{
if (!set.isValidIndex(i))
{
// Skip masked pixels and out of bounds.
indices |= (uint)3 << (int)(2 * i);
continue;
}
Vector3 color = new Vector3(set.color[i].x, set.color[i].y, set.color[i].z);
float d0 = colorDistance(palette[0], color);
float d1 = colorDistance(palette[1], color);
float d2 = colorDistance(palette[2], color);
uint index;
if (d0 < d1 && d0 < d2)
{
index = 0;
}
else if (d1 < d2)
{
index = 1;
}
else
{
index = 2;
}
indices |= index << (int)(2 * i);
}
return(indices);
}
// maxColor and minColor are expected to be in the same range as the color set.
static uint computeIndices4(ColorSet set, Vector3 maxColor, Vector3 minColor)
{
Vector3[] palette = new Vector3[4];
palette[0] = maxColor;
palette[1] = minColor;
palette[2] = Vector3.Lerp(palette[0], palette[1], 1.0f / 3.0f);
palette[3] = Vector3.Lerp(palette[0], palette[1], 2.0f / 3.0f);
Vector3[] row0 = new Vector3[6];
Vector3[] row1 = new Vector3[6];
uint indices = 0;
//for(int i = 0; i < 16; i++)
for (uint y = 0; y < 4; y++)
{
for (uint x = 0; x < 4; x++)
{
uint i = y * 4 + x;
if (!set.isValidIndex(i))
{
// Skip masked pixels and out of bounds.
continue;
}
Vector3 color = new Vector3(set.color[i].x, set.color[i].y, set.color[i].z);
// Add error.
color += row0[1 + x];
float d0 = colorDistance(palette[0], color);
float d1 = colorDistance(palette[1], color);
float d2 = colorDistance(palette[2], color);
float d3 = colorDistance(palette[3], color);
uint b0 = d0 > d3?(uint)1:(uint)0;
uint b1 = d1 > d2?(uint)1:(uint)0;
uint b2 = d0 > d2?(uint)1:(uint)0;
uint b3 = d1 > d3?(uint)1:(uint)0;
uint b4 = d2 > d3?(uint)1:(uint)0;
uint x0 = b1 & b2;
uint x1 = b0 & b3;
uint x2 = b0 & b4;
uint index = x2 | ((x0 | x1) << 1);
indices |= index << (int)(2 * i);
// Compute new error.
Vector3 diff = color - palette[index];
// Propagate new error.
//row0[1+x+1] += 7.0f / 16.0f * diff;
//row1[1+x-1] += 3.0f / 16.0f * diff;
//row1[1+x+0] += 5.0f / 16.0f * diff;
//row1[1+x+1] += 1.0f / 16.0f * diff;
}
swap(ref row0, ref row1);
row1 = new Vector3[6];
}
return(indices);
}
