Script meant to randomize camera position does not point the camera back to the object. What script do I need to point camera back at object?

Question

I am writing a script that randomizes camera position in relation to a single object, but most of the time when I render the object is not in view so I get the plain grey background. I think there is a flaw in the class that reorients the camera so that the object is within the frame. Can help me? Here is the class meant to point the camera back towards the object. I am on blender version 2.81.16, which is the latest version that is compatible with a plug in I need.

def point_camera(camera, point=(0., 0., 0.)):
    """ point camera to 'location' looking directly at origin
    args:
        location: list of 3 representing the location to point at
        origin: list of floats that represent where the camera
        will be looking at
    returns:
        None
    """
    point = Vector(point)
    camera_location = camera.location
    direction = point - camera_location
    quaternion_rotation = direction.to_track_quat('-Z', 'Y')
    euler_rotation = quaternion_rotation.to_euler()
    camera.rotation_euler = euler_rotation

Thank you

Answer 1

Global Coordinates

Recommend you work in global coordinates

camera_location = camera.matrix_world.to_translation() 

and set the cameras world matrix.

import bpy
from mathutils import Vector

def point_camera(camera, point=Vector()):
    point = Vector(point) # recast len 3 iterable
    cmw = camera.matrix_world
    direction = cmw.translation - point
    M = direction.to_track_quat('Z', 'Y').to_matrix().to_4x4()
    M.translation = cmw.translation

    camera.matrix_world = M
    
# test call

point_camera(bpy.context.scene.camera, (0, 0, 0))

Also at play here if pointing to an object is the objects origin can be anywhere... so if using a track to constraint may be easiest to track to an empty, and place the empty at objects bounding box centre (for example)

Given a mesh object ob its global bounding box centre location would be

bbc = ob.matrix_world @ sum((Vector(v) for v in ob.bound_box), Vector()) / 8 

Note: Object constraints, drivers and keyframes all work together to create an objects world matrix. Keep this in mind, as code above that sets the matrix world may produce strange results on constrained (or otherwise set) objects.