《Focus On 3D Terrain Programming》中一段代码的注释三

取自《Focus On 3D Terrain Programming》中的一段:

//--------------------------------------------------------------
// Name:          CIMAGE::LoadUncompressedTGA - private
// Description:   Load an uncompressed targa (TGA)
// Arguments:     None
// Return Value:  A boolean variable: -true: TGA was loaded
//                                    -false: TGA was not loaded
//--------------------------------------------------------------
bool CIMAGE::LoadUncompressedTGA( void )
{
  ........
  ....
  pTGAinfo.m_uiBytesPerPixel= m_uiBPP/8;
  pTGAinfo.m_uiImageSize    = ( pTGAinfo.m_uiBytesPerPixel*m_uiWidth*m_uiHeight );

  //copy the image data
  memcpy( m_ucpData, ucpFile, pTGAinfo.m_uiImageSize );

  //byte swapping ( optimized by Steve Thomas )
  for( uiCSwap=0; uiCSwap<( int )pTGAinfo.m_uiImageSize; uiCSwap+=pTGAinfo.m_uiBytesPerPixel )
  {
    m_ucpData[uiCSwap]^= m_ucpData[uiCSwap+2]^=m_ucpData[uiCSwap]^= m_ucpData[uiCSwap+2];
  }

  //the uncompressed TGA has been successfully loaded
  return true;
}

===============

开开眼界，把BGR转换为RGB的交换代码，过于高大上了，直接操作的硬件，可以提高一定的速度，对大图片有用。

    m_ucpData[uiCSwap]^= m_ucpData[uiCSwap+2]^=m_ucpData[uiCSwap]^= m_ucpData[uiCSwap+2];