LooToRotation

gistfile1.cpp

void	Matrix4x4::BuildLookAtMatrix(float posx,float posy,float posz,float eyex,float eyey, float eyez,float upx,float upy, float upz)
{
   float x[3], y[3], z[3];
   float mag;

   z[0] = eyex - posx;
   z[1] = eyey - posy;
   z[2] = eyez - posz;
   mag = sqrt( z[0]*z[0] + z[1]*z[1] + z[2]*z[2] );
   if (mag>.0001) 
   {  
	  mag	=	1/mag;
      z[0] *= mag;
      z[1] *= mag;
      z[2] *= mag;
   }

   y[0] = upx;
   y[1] = upy;
   y[2] = upz;

   x[0] =  y[1]*z[2] - y[2]*z[1];
   x[1] = -y[0]*z[2] + y[2]*z[0];
   x[2] =  y[0]*z[1] - y[1]*z[0];


   y[0] =  z[1]*x[2] - z[2]*x[1];
   y[1] = -z[0]*x[2] + z[2]*x[0];
   y[2] =  z[0]*x[1] - z[1]*x[0];

   mag = sqrt( x[0]*x[0] + x[1]*x[1] + x[2]*x[2] );
   if (mag > .0001) 
   {
	  mag	=	1/mag;
      x[0] *= mag;
      x[1] *= mag;
      x[2] *= mag;
   }

   mag = sqrt( y[0]*y[0] + y[1]*y[1] + y[2]*y[2] );
   if (mag > .0001) 
   {
	  mag = 1/mag;
	  y[0] *= mag;
      y[1] *= mag;
      y[2] *= mag;
   }

#define M(row,col)  mat[row][col]
   M(0,0) = x[0];  M(0,1) = x[1];  M(0,2) = x[2];  M(0,3) = -x[0]*eyex + -x[1]*eyey + -x[2]*eyez;
   M(1,0) = y[0];  M(1,1) = y[1];  M(1,2) = y[2];  M(1,3) = -y[0]*eyex + -y[1]*eyey + -y[2]*eyez;
   M(2,0) = z[0];  M(2,1) = z[1];  M(2,2) = z[2];  M(2,3) = -z[0]*eyex + -z[1]*eyey + -z[2]*eyez;
   M(3,0) = 0.0;   M(3,1) = 0.0;   M(3,2) = 0.0;   M(3,3) = 1.0;
#undef M	
}