public static void Compress8BitBlock(byte[] source, int sourcePosition, int sourceLineLength, byte[] destination, int destPosition, int channel, bool isSigned, DDSFormatDetails formatDetails)
{
// KFreon: Get min and max
byte min = 255;
byte max = 0;
int channelBitSize = channel * formatDetails.ComponentSize;
int count = sourcePosition + channelBitSize;
byte[] sourceTexel = new byte[16];
int sourceTexelInd = 0;
for (int i = 1; i <= 4; i++)
{
for (int j = 0; j < 4; j++)
{
byte color = formatDetails.ReadByte(source, count);
sourceTexel[sourceTexelInd++] = color; // Cache source
if (color > max)
{
max = color;
}
else if (color < min)
{
min = color;
}
count += 4 * formatDetails.ComponentSize; // skip to next entry in channel
}
count = sourcePosition + channelBitSize + sourceLineLength * i;
}
// Build Palette
byte[] Colors = Build8BitPalette(min, max, isSigned);
// Compress Pixels
ulong line = 0;
sourceTexelInd = 0;
for (int i = 0; i < 4; i++)
{
for (int j = 0; j < 4; j++)
{
int ind = (i << 2) + j;
byte color = sourceTexel[sourceTexelInd++];
int index = GetClosestValue(Colors, color);
line |= (ulong)index << (ind * 3);
}
}
byte[] compressed = BitConverter.GetBytes(line);
destination[destPosition] = min;
destination[destPosition + 1] = max;
for (int i = 2; i < 8; i++)
{
destination[destPosition + i] = compressed[i - 2];
}
}
static void WriteUncompressedPixel(byte[] source, int sourceStart, int[] sourceInds, DDSFormatDetails sourceFormatDetails, uint[] masks,
byte[] destination, int destStart, int[] destInds, DDSFormatDetails destFormatDetails, bool oneChannel, bool twoChannel, bool requiresSignedAdjust)
{
if (twoChannel) // No large components - silly spec...
{
byte red = sourceFormatDetails.ReadByte(source, sourceStart);
byte alpha = sourceFormatDetails.ReadByte(source, sourceStart + 3 * sourceFormatDetails.ComponentSize);
destination[destStart] = masks[3] > masks[2] ? red : alpha;
destination[destStart + 1] = masks[3] > masks[2] ? alpha : red;
}
else if (oneChannel) // No large components - silly spec...
{
byte blue = sourceFormatDetails.ReadByte(source, sourceStart);
byte green = sourceFormatDetails.ReadByte(source, sourceStart + 1 * sourceFormatDetails.ComponentSize);
byte red = sourceFormatDetails.ReadByte(source, sourceStart + 2 * sourceFormatDetails.ComponentSize);
byte alpha = sourceFormatDetails.ReadByte(source, sourceStart + 3 * sourceFormatDetails.ComponentSize);
destination[destStart] = (byte)(blue * 0.082 + green * 0.6094 + blue * 0.3086); // Weightings taken from ATI Compressonator. Dunno if this changes things much.
}
else
{
// Handle weird conditions where array isn't long enough...
if (sourceInds[3] + sourceStart >= source.Length)
{
return;
}
for (int i = 0; i < 4; i++)
{
uint mask = masks[i];
if (mask != 0)
{
destFormatDetails.WriteColor(source, sourceStart + sourceInds[i], sourceFormatDetails, destination, destStart + destInds[i]);
}
}
// Signed adjustments - Only happens for bytes for now. V8U8
if (requiresSignedAdjust)
{
destination[destStart + destInds[2]] += 128;
destination[destStart + destInds[1]] += 128;
}
}
}
void WriteByte(byte[] source, int sourceStart, DDSFormatDetails sourceFormatDetails, byte[] destination, int destStart)
{
destination[destStart] = sourceFormatDetails.ReadByte(source, sourceStart);
}
