   Programming RPG with DirectX book question
  Hi, in the book GameCore source,BOOL cLight:oint(float XFrom, float YFrom, float ZFrom,    float XAt,   float YAt,   float ZAt){  D3DXVECTOR3 vecSrc;  D3DXVECTOR3 vecDest;  // Move the light  Move(XFrom, YFrom, ZFrom);  // Calculate vector between angles  m_Light.Direction.x = XAt - XFrom;  m_Light.Direction.y = YAt - YFrom;  m_Light.Direction.z = ZAt - ZFrom;  return TRUE;}what are the 2 vector for ? thanks  
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