Simple Blender script for computing distance between plane (camera) and point.

blender_dist_pnt_to_plane.py

"""
Demonstration of computation distance point to plane. Plane is represented by normal
vector and point laying at the plane.
"""

import bpy
import mathutils


def main():
    """
    Example of distance_point_to_plane
    """
    # Get active camera object
    cam = bpy.context.scene.camera

    # Get rotation of camera
    cam.rotation_mode = 'QUATERNION'
    quat = cam.rotation_quaternion

    # Blender camera looks to scene in -Z direction
    norm_vec = quat.to_matrix() * mathutils.Vector((0, 0, -1))

    # Get vector representing camera location
    cam_loc = cam.location

    # Set position of some testing point
    point = mathutils.Vector((1.0, 1.0, 1.0))

    # Compute distance between point and plane of camera
    distance = mathutils.geometry.distance_point_to_plane(point, cam_loc, norm_vec)

    return distance

if __name__ == '__main__':
    print(main())