Game Physics Engine Development, 2nd Edition

14.2 Collision Impulses 345

* directions are set so that they are at right angles to it.

*/

void Contact::calculateContactBasis()

{

Vector3 contactTangent[2];

// Check whether the Z-axis is nearer to the X- or Y-axis

if (real_abs(contactNormal.x) > real_abs(contactNormal.y))

{

// Scaling factor to ensure the results are normalized.

const real s = (real)1.0f/

real_sqrt(contactNormal.z*contactNormal.z +

contactNormal.x*contactNormal.x);

// The new X-axis is at right angles to the world Y-axis.

contactTangent[0].x = contactNormal.z*s;

contactTangent[0].y = 0;

contactTangent[0].z = -contactNormal.x*s;

// The new Y-axis is at right angles to the new X- and Z-axes. ...