public Color[] Decompress(byte[] blockData) { Debug.Assert(blockData.Length == BlockFormat.BC3ByteSize); var block = BC3BlockData.FromBytes(blockData); var colorTable = BC1ColorTable.Create(block.Color0, block.Color1); var alphaTable = CreateAlphaTable(block.Alpha0, block.Alpha1); var colors = new Color[BlockFormat.TexelCount]; for (int i = 0; i < colors.Length; ++i) { int colorIndex = block.ColorIndexes[i]; int alphaIndex = block.AlphaIndexes[i]; var color = colorTable[colorIndex]; var alpha = alphaTable[alphaIndex]; colors[i] = Color.FromArgb(alpha, ColorUtility.To32Bit(color)); } return(colors); }
/// <summary> /// Instantiates a <see cref="BC3BlockData"/> from compressed BC3 block data. /// </summary> /// <param name="bytes">The data of a BC3 compressed block.</param> public static BC3BlockData FromBytes(byte[] bytes) { Debug.Assert(bytes.Length == BlockFormat.BC3ByteSize, "Mismatching number of bytes for format."); byte alpha0 = bytes[0]; byte alpha1 = bytes[1]; byte[] alphas = new byte[6]; alphas[2] = bytes[2]; alphas[1] = bytes[3]; alphas[0] = bytes[4]; alphas[5] = bytes[5]; alphas[4] = bytes[6]; alphas[3] = bytes[7]; byte c0Low = bytes[8]; byte c0Hi = bytes[9]; byte c1Low = bytes[10]; byte c1Hi = bytes[11]; byte[] indexes = new byte[4]; indexes[0] = bytes[12]; indexes[1] = bytes[13]; indexes[2] = bytes[14]; indexes[3] = bytes[15]; var block = new BC3BlockData(); block.Alpha0 = alpha0; block.Alpha1 = alpha1; block.Color0 = Color565.FromValue((ushort)((c0Hi << 8) | c0Low)); block.Color1 = Color565.FromValue((ushort)((c1Hi << 8) | c1Low)); block.AlphaIndexes[0] = alphas[0] & 0x07; // xxxx x111 block.AlphaIndexes[1] = (alphas[0] >> 3) & 0x07; // xx11 1xxx block.AlphaIndexes[2] = ((alphas[0] >> 6) & 0x03) | // 11xx xxxx LSB ((alphas[1] & 0x01) << 2); // xxxx xxx1 MSB block.AlphaIndexes[3] = (alphas[1] >> 1) & 0x07; // xxxx 111x block.AlphaIndexes[4] = (alphas[1] >> 4) & 0x07; // x111 xxxx block.AlphaIndexes[5] = ((alphas[1] >> 7) & 0x01) | // 1xxx xxxx LSB ((alphas[2] & 0x03) << 1); // xxxx xx11 MSB block.AlphaIndexes[6] = (alphas[2] >> 2) & 0x07; // xxx1 11xx block.AlphaIndexes[7] = (alphas[2] >> 5) & 0x07; // 111x xxxx block.AlphaIndexes[8] = alphas[3] & 0x07; // xxxx x111 block.AlphaIndexes[9] = (alphas[3] >> 3) & 0x07; // xx11 1xxx block.AlphaIndexes[10] = ((alphas[3] >> 6) & 0x03) | // 11xx xxxx LSB ((alphas[4] & 0x01) << 2); // xxxx xxx1 MSB block.AlphaIndexes[11] = (alphas[4] >> 1) & 0x07; // xxxx 111x block.AlphaIndexes[12] = (alphas[4] >> 4) & 0x07; // x111 xxxx block.AlphaIndexes[13] = ((alphas[4] >> 7) & 0x01) | // 1xxx xxxx LSB ((alphas[5] & 0x03) << 1); // xxxx xx11 MSB block.AlphaIndexes[14] = (alphas[5] >> 2) & 0x07; // xxx1 11xx block.AlphaIndexes[15] = (alphas[5] >> 5) & 0x07; // 111x xxxx for (int p = 0, row = 0; p < BlockFormat.TexelCount; p += BlockFormat.Dimension, ++row) { int a = p; int b = p + 1; int c = p + 2; int d = p + 3; block.ColorIndexes[a] = indexes[row] & 0x03; block.ColorIndexes[b] = (indexes[row] >> 2) & 0x03; block.ColorIndexes[c] = (indexes[row] >> 4) & 0x03; block.ColorIndexes[d] = (indexes[row] >> 6) & 0x03; } return(block); }