/// <summary>
/// Given a block, extract the colour information and convert to 5554 formats
/// </summary>
private void Unpack5554Colour(AmtcBlock block, int[,] abColors)
{
// extract A and B
// 15 bits (shifted up by one)
m_rawBits[0] = block.PackedData1 & (0xFFFE);
// 16 bits
m_rawBits[1] = block.PackedData1 >> 16;
// step through both colours
for (int i = 0; i < 2; i++)
{
// if completely opaque
if ((m_rawBits[i] & (1 << 15)) != 0)
{
// extract R and G (both 5 bit)
abColors[i, 0] = (int)((m_rawBits[i] >> 10) & 0x1F);
abColors[i, 1] = (int)((m_rawBits[i] >> 5) & 0x1F);
// The precision of Blue depends on A or B. If A then we need to replicate the top bit to get 5 bits in total
abColors[i, 2] = (int)(m_rawBits[i] & 0x1F);
if (i == 0)
{
abColors[0, 2] |= abColors[0, 2] >> 4;
}
// set 4bit alpha fully on...
abColors[i, 3] = 0xF;
}
// else if colour has variable translucency
else
{
// extract R and G (both 4 bit). Leave a space on the end for the replication of bits
abColors[i, 0] = (int)((m_rawBits[i] >> (8 - 1)) & 0x1E);
abColors[i, 1] = (int)((m_rawBits[i] >> (4 - 1)) & 0x1E);
// replicate bits to truly expand to 5 bits
abColors[i, 0] |= abColors[i, 0] >> 4;
abColors[i, 1] |= abColors[i, 1] >> 4;
// grab the 3(+padding) or 4 bits of blue and add an extra padding bit
abColors[i, 2] = (int)((m_rawBits[i] & 0xF) << 1);
// expand from 3 to 5 bits if this is from colour A, or 4 to 5 bits if from colour B
if (i == 0)
{
abColors[0, 2] |= abColors[0, 2] >> 3;
}
else
{
abColors[0, 2] |= abColors[0, 2] >> 4;
}
// set the alpha bits to be 3 + a zero on the end
abColors[i, 3] = (int)((m_rawBits[i] >> 11) & 0xE);
}
}
}
private static AmtcBlock[] GenerateBlocks(byte[] input)
{
AmtcBlock[] blocks = new AmtcBlock[input.Length / 8];
using (MemoryStream ms = new MemoryStream(input))
{
using (BinaryReader reader = new BinaryReader(ms))
{
int i = 0;
while (reader.BaseStream.Position != reader.BaseStream.Length)
{
uint v0 = reader.ReadUInt32();
uint v1 = reader.ReadUInt32();
AmtcBlock block = new AmtcBlock(v0, v1);
blocks[i++] = block;
}
}
}
return(blocks);
}
/// <summary>
/// Given the block and the texture type and it's relative position in the 2x2 group of blocks, extract the bit patterns for the fully defined pixels.
/// </summary>
private static void UnpackModulations(AmtcBlock block, bool do2bitMode, int[,] modulationVals, int[,] modulationModes, int startX, int startY)
{
int blockModMode = (int)(block.PackedData1 & 1);
uint modulationBits = block.PackedData0;
// if it's in an interpolated mode
if (do2bitMode && (blockModMode != 0))
{
// run through all the pixels in the block. Note we can now treat all the "stored" values as if they have 2bits (even when they didn't!)
for (int y = 0; y < BlockYSize; y++)
{
for (int x = 0; x < BlockX2bpp; x++)
{
modulationModes[y + startY, x + startX] = blockModMode;
// if this is a stored value...
if (((x ^ y) & 1) == 0)
{
modulationVals[y + startY, x + startX] = (int)(modulationBits & 3);
modulationBits >>= 2;
}
}
}
}
// else if direct encoded 2bit mode - i.e. 1 mode bit per pixel
else if (do2bitMode)
{
for (int y = 0; y < BlockYSize; y++)
{
for (int x = 0; x < BlockX2bpp; x++)
{
modulationModes[y + startY, x + startX] = blockModMode;
// double the bits so 0=> 00, and 1=>11
if ((modulationBits & 1) != 0)
{
modulationVals[y + startY, x + startX] = 0x3;
}
else
{
modulationVals[y + startY, x + startX] = 0x0;
}
modulationBits >>= 1;
}
}
}
// else its the 4bpp mode so each value has 2 bits
else
{
for (int y = 0; y < BlockYSize; y++)
{
for (int x = 0; x < BlockX4bpp; x++)
{
modulationModes[y + startY, x + startX] = blockModMode;
modulationVals[y + startY, x + startX] = (int)(modulationBits & 3);
modulationBits >>= 2;
}
}
}
// make sure nothing is left over
if (modulationBits != 0)
{
throw new Exception("Something is left over");
}
}
