Method readHeader

Engine/source/gfx/bitmap/ddsLoader.cpp:237–545

}

bool DDSFile::readHeader(Stream &s)
{
   U32 tmp;

   // Read the FOURCC
   s.read(&tmp);

   if(tmp != MakeFourCC('D', 'D', 'S', ' '))
   {
      Con::errorf("DDSFile::readHeader - unexpected magic number, wanted 'DDS '!");
      return false;
   }

   // Read the size of the header.
   s.read(&tmp);

   if(tmp != 124)
   {
      Con::errorf("DDSFile::readHeader - incorrect header size. Expected 124 bytes.");
      return false;
   }

   // Read some flags...
   U32 ddsdFlags;
   s.read(&ddsdFlags);

   // "Always include DDSD_CAPS, DDSD_PIXELFORMAT, DDSD_WIDTH, DDSD_HEIGHT."
   if(!(ddsdFlags & (DDSDCaps | DDSDPixelFormat | DDSDWidth | DDSDHeight)))
   {
      Con::errorf("DDSFile::readHeader - incorrect surface description flags.");
      return false;
   }

   // Read height and width (always present)
   s.read(&mHeight);
   s.read(&mWidth);

   // Read pitch or linear size.

   // First make sure we have valid flags (either linear size or pitch).
   if((ddsdFlags & (DDSDLinearSize | DDSDPitch)) == (DDSDLinearSize | DDSDPitch))
   {
      // Both are invalid!
      Con::errorf("DDSFile::readHeader - encountered both DDSD_LINEARSIZE and DDSD_PITCH!");
      return false;
   }

   // Ok, some flags are set, so let's do some reading.
   s.read(&mPitchOrLinearSize);

   if(ddsdFlags & DDSDLinearSize)
   {
      mFlags.set(LinearSizeFlag); // ( mHeight / 4 ) * ( mWidth / 4 ) * DDSSIZE
   }
   else if (ddsdFlags & DDSDPitch)
   {
      mFlags.set(PitchSizeFlag); // ( mWidth / 4 ) * DDSSIZE ???
   }