How do I move a target camera along Y axis

Question

I have a camera that rotates around a target point on mouse move. How can I move the camera's position upwards/downwards related to the target position? So when camera is moved upwards the object is seen to go downwards and opposite.

I was trying to change target vector y, camera position vector y but none of it really worked:

void Camera::move(float dir)
{
    m_target.y += dir;
}

and

void Camera::move(float dir)
{
    m_pos.y += dir;
}

I got to confess I'm not strong at linear algebra and most likely that's the reason why I don't understand it well. I was trying to google it however all results are about forward/backward camera movement which is as easy as to change m_radius class member.

My camera's position is described by radius, theta and phi angles (spherical coordinates it's called, I guess).

This is how I set position m_posand then call XMMatrixLookAtLH

setPosition(m_target.x + m_radius * cosf(m_theta) * cosf(m_phi), m_target.y + m_radius * sinf(m_theta), m_target.z + m_radius * cosf(m_theta) * sinf(m_phi));
setLookAt(XMLoadFloat3(&m_pos), XMVectorZero(), XMLoadFloat3(&m_up));

Target is always set in origin (0, 0, 0) because all my model data is loaded related to the origin. I added target position effect to the setPosition() method just in case I will ever need to change it.

Answer 1

If I understood what you wanted to do correctly, you will have to do some vector addition. Create a vertical vector B of length equal to the distance you want to move up (say (0,2,0) for a vertical distance of 2), and add it to the pos vector. Set your new pos vector to the result of the addition.

If you want to visualize it:

Here A would be your pos vector and B your upward movement. Note that B here is not vertical, it's just an example.