unity-vector3-refract.cs

unity-vector3-refract.cs

/**
  * returns:
  *  normalized Vector3 refracted by passing from one medium to another in a realistic manner according to Snell's Law
  *
  * parameters:
  *  RI1 - the refractive index of the first medium
  *  RI2 - the refractive index of the second medium
  *  surfNorm - the normal of the interface between the two mediums (for example the normal returned by a raycast)
  *  incident - the incoming Vector3 to be refracted
  *
  * usage example (laser pointed from a medium with RI roughly equal to air through a medium with RI roughly equal to water):
  *  Vector3 laserRefracted = Refract(1.0f, 1.33f, waterPointNorm, laserForward);
*/
public static Vector3 Refract(float RI1, float RI2, Vector3 surfNorm, Vector3 incident)
{
	surfNorm.Normalize(); //should already be normalized, but normalize just to be sure
	incident.Normalize();

	return (RI1/RI2 * Vector3.Cross(surfNorm, Vector3.Cross(-surfNorm, incident)) - surfNorm * Mathf.Sqrt(1 - Vector3.Dot(Vector3.Cross(surfNorm, incident)*(RI1/RI2*RI1/RI2), Vector3.Cross(surfNorm, incident)))).normalized;
}