GPGPU Programming for Games and Science

Linear and Affine Algebra 317

e.angle [0] = 0;

e.angle [1] = −sign∗ pi /2;

e.angle [2] = atan2(− sign∗ r(e. axis [1] ,e. axis [0]) ,

r(e. axis [1] ,e. axis [1]));

e. result = NOT

UNIQUE SUM ;

}

}

else

{

// Map (0,2,0), (1,0,1), and (2,1,2) to −1. Map (0,1,0), (1,2,1),

// and (2,0,2) to +1.

int b2 = 3 − e.axis[0] − e. axis [1];

int parity = (((b2 | (e. axis [1] << 2)) >> e. axis [0]) & 1);

Real const sign = ( parity & 1 ? −1 : +1);

if (r(e. axis [0] ,e. axis [0]) < 1)

{

if (r(e.axis[0],e.axis[0]) > −1)

{

e.angle [0] = atan2(r(e. axis [1] ,e. axis [0]) ,

sign∗ r(b2,e. axis [0]));

e.angle[1] = acos(r(e.axis[0],e.axis [0]));

e.angle [2] = atan2(r(e. axis [0] ,e. axis [1]) ...