protected override void Initalize()
{
// Check to see if what we are dealing with is a GVR texture
if (!Is(encodedData))
{
throw new NotAValidTextureException("This is not a valid GVR texture.");
}
// Determine the offsets of the GBIX/GCIX (if present) and GCIX header chunks.
if (PTMethods.Contains(encodedData, 0, Encoding.UTF8.GetBytes("GBIX")) ||
PTMethods.Contains(encodedData, 0, Encoding.UTF8.GetBytes("GCIX")))
{
gbixOffset = 0x00;
pvrtOffset = 0x10;
}
else
{
gbixOffset = -1;
pvrtOffset = 0x00;
}
// Read the global index (if it is present). If it is not present, just set it to 0.
if (gbixOffset != -1)
{
globalIndex = PTMethods.ToUInt32BE(encodedData, gbixOffset + 0x08);
}
else
{
globalIndex = 0;
}
// Read information about the texture
textureWidth = PTMethods.ToUInt16BE(encodedData, pvrtOffset + 0x0C);
textureHeight = PTMethods.ToUInt16BE(encodedData, pvrtOffset + 0x0E);
pixelFormat = (GvrPixelFormat)(encodedData[pvrtOffset + 0x0A] >> 4); // Only the first 4 bits matter
dataFlags = (GvrDataFlags)(encodedData[pvrtOffset + 0x0A] & 0x0F); // Only the last 4 bits matter
dataFormat = (GvrDataFormat)encodedData[pvrtOffset + 0x0B];
// Get the codecs and make sure we can decode using them
dataCodec = GvrDataCodec.GetDataCodec(dataFormat);
// We need a pixel codec if this is a palettized texture
if (dataCodec != null && dataCodec.PaletteEntries != 0)
{
pixelCodec = GvrPixelCodec.GetPixelCodec(pixelFormat);
if (pixelCodec != null)
{
dataCodec.PixelCodec = pixelCodec;
canDecode = true;
}
}
else
{
pixelFormat = GvrPixelFormat.Unknown;
if (dataCodec != null)
{
canDecode = true;
}
}
// Set the palette and data offsets
paletteEntries = dataCodec.PaletteEntries;
if (!canDecode || paletteEntries == 0 || (paletteEntries != 0 && (dataFlags & GvrDataFlags.ExternalPalette) != 0))
{
paletteOffset = -1;
dataOffset = pvrtOffset + 0x10;
}
else
{
paletteOffset = pvrtOffset + 0x10;
dataOffset = paletteOffset + (paletteEntries * (pixelCodec.Bpp >> 3));
}
// If the texture contains mipmaps, gets the offsets of them
if (canDecode && paletteEntries == 0 && (dataFlags & GvrDataFlags.Mipmaps) != 0)
{
mipmapOffsets = new int[(int)Math.Log(textureWidth, 2) + 1];
int mipmapOffset = 0;
for (int i = 0, size = textureWidth; i < mipmapOffsets.Length; i++, size >>= 1)
{
mipmapOffsets[i] = mipmapOffset;
mipmapOffset += Math.Max(size * size * (dataCodec.Bpp >> 3), 32);
}
}
initalized = true;
}