/** @see Surface#getNormal() */
@Override
public Vector getNormal(Point point) {
// TODO: return vector representing this surface's normal at this point
Vector ab = b.sub(a);
Vector ac = c.sub(a);
return ab.cross(ac).normalize();
}
/** @see Surface#getIntersection() */
@Override
public double[] getIntersection(Ray ray) {
// TODO: return t values at which this ray intersects this surface
Vector ab = b.sub(a);
Vector ac = c.sub(a);
Vector acDir = ray.getDirection().cross(ac);
double div = acDir.dot(ab);
Vector distance = ray.getOrigin().sub(a);
// get first barycentric coordinate
double bary1 = distance.dot(acDir) / div;
if (bary1 < 0 || bary1 > 1) {
return new double[0];
}
// get second barycentric coordinate
Vector abDistCross = distance.cross(ab);
double bary2 = ray.getDirection().dot(abDistCross) / div;
if (bary2 < 0 || bary1 + bary2 > 1) {
return new double[0];
}
// calculate t
double t = ac.dot(abDistCross) / div;
double[] ts = {t};
return ts;
}