/**
* Setup this camera such that it looks at the specified point with the specified view direction, up direction, and the distance from the point.
*
* @param p the target point that this camera will look at
* @param vd the view direction
* @param up the up direction
* @param d the distance between the center of this camera and the target
*/
void PPC::LookAt(const V3 &p, const V3 &vd, const V3 &up, float d) {
float f = GetFocalLength();
C = p - vd.UnitVector() * d;
a = (vd ^ up).UnitVector() * a.Length();
b = (vd ^ a).UnitVector() * b.Length();
c = vd.UnitVector() * f - a * ((float)w / 2.0f) - b * ((float)h / 2.0f);
SetPMat();
}
/**
* Setup this camera according to the specified center, vector a, and the view direction.
*
* @param C the center of the camera
* @param a the vector a (The horizontal direction of the screen)
* @param vd the view direction of the camera
*/
void PPC::Set(const V3& C, const V3& a, const V3& vd) {
this->C = C;
this->a = a;
b = (vd ^ a).UnitVector() * b.Length();
c = vd.UnitVector() * GetFocalLength() - a * ((float)w/2.0f) - b * ((float)h/2.0f);
SetPMat();
}
