3b1b-manim/manimlib/camera/camera_frame.py

from __future__ import annotations

import math

import numpy as np
from scipy.spatial.transform import Rotation

from manimlib.constants import DEGREES, RADIANS
from manimlib.constants import FRAME_HEIGHT, FRAME_WIDTH
from manimlib.constants import DOWN, LEFT, ORIGIN, OUT, RIGHT, UP
from manimlib.mobject.mobject import Mobject
from manimlib.utils.space_ops import normalize

from typing import TYPE_CHECKING

if TYPE_CHECKING:
    from manimlib.typing import Vect3


class CameraFrame(Mobject):
    def __init__(
        self,
        frame_shape: tuple[float, float] = (FRAME_WIDTH, FRAME_HEIGHT),
        center_point: Vect3 = ORIGIN,
        focal_dist_to_height: float = 2.0,
        **kwargs,
    ):
        self.frame_shape = frame_shape
        self.center_point = center_point
        self.focal_dist_to_height = focal_dist_to_height
        self.view_matrix = np.identity(4)
        super().__init__(**kwargs)

    def init_uniforms(self) -> None:
        super().init_uniforms()
        # As a quaternion
        self.uniforms["orientation"] = Rotation.identity().as_quat()
        self.uniforms["focal_dist_to_height"] = self.focal_dist_to_height

    def init_points(self) -> None:
        self.set_points([ORIGIN, LEFT, RIGHT, DOWN, UP])
        self.set_width(self.frame_shape[0], stretch=True)
        self.set_height(self.frame_shape[1], stretch=True)
        self.move_to(self.center_point)

    def set_orientation(self, rotation: Rotation):
        self.uniforms["orientation"][:] = rotation.as_quat()
        return self

    def get_orientation(self):
        return Rotation.from_quat(self.uniforms["orientation"])

    def to_default_state(self):
        self.center()
        self.set_height(FRAME_HEIGHT)
        self.set_width(FRAME_WIDTH)
        self.set_orientation(Rotation.identity())
        return self

    def get_euler_angles(self):
        return self.get_orientation().as_euler("zxz")[::-1]

    def get_theta(self):
        return self.get_euler_angles()[0]

    def get_phi(self):
        return self.get_euler_angles()[1]

    def get_gamma(self):
        return self.get_euler_angles()[2]

    def get_inverse_camera_rotation_matrix(self):
        return self.get_orientation().as_matrix().T

    def get_view_matrix(self):
        """
        Returns a 4x4 for the affine transformation mapping a point
        into the camera's internal coordinate system
        """
        result = self.view_matrix
        result[:] = np.identity(4)
        result[:3, 3] = -self.get_center()
        rotation = np.identity(4)
        rotation[:3, :3] = self.get_inverse_camera_rotation_matrix()
        result[:] = np.dot(rotation, result)
        return result

    def rotate(self, angle: float, axis: np.ndarray = OUT, **kwargs):
        rot = Rotation.from_rotvec(angle * normalize(axis))
        self.set_orientation(rot * self.get_orientation())
        return self

    def set_euler_angles(
        self,
        theta: float | None = None,
        phi: float | None = None,
        gamma: float | None = None,
        units: float = RADIANS
    ):
        eulers = self.get_euler_angles()  # theta, phi, gamma
        for i, var in enumerate([theta, phi, gamma]):
            if var is not None:
                eulers[i] = var * units
        self.set_orientation(Rotation.from_euler("zxz", eulers[::-1]))
        return self

    def reorient(
        self,
        theta_degrees: float | None = None,
        phi_degrees: float | None = None,
        gamma_degrees: float | None = None,
    ):
        """
        Shortcut for set_euler_angles, defaulting to taking
        in angles in degrees
        """
        self.set_euler_angles(theta_degrees, phi_degrees, gamma_degrees, units=DEGREES)
        return self

    def set_theta(self, theta: float):
        return self.set_euler_angles(theta=theta)

    def set_phi(self, phi: float):
        return self.set_euler_angles(phi=phi)

    def set_gamma(self, gamma: float):
        return self.set_euler_angles(gamma=gamma)

    def increment_theta(self, dtheta: float):
        self.rotate(dtheta, OUT)
        return self

    def increment_phi(self, dphi: float):
        self.rotate(dphi, self.get_inverse_camera_rotation_matrix()[0])
        return self

    def increment_gamma(self, dgamma: float):
        self.rotate(dgamma, self.get_inverse_camera_rotation_matrix()[2])
        return self

    def set_focal_distance(self, focal_distance: float):
        self.uniforms["focal_dist_to_height"] = focal_distance / self.get_height()
        return self

    def set_field_of_view(self, field_of_view: float):
        self.uniforms["focal_dist_to_height"] = 2 * math.tan(field_of_view / 2)
        return self

    def get_shape(self):
        return (self.get_width(), self.get_height())

    def get_center(self) -> np.ndarray:
        # Assumes first point is at the center
        return self.get_points()[0]

    def get_width(self) -> float:
        points = self.get_points()
        return points[2, 0] - points[1, 0]

    def get_height(self) -> float:
        points = self.get_points()
        return points[4, 1] - points[3, 1]

    def get_focal_distance(self) -> float:
        return self.uniforms["focal_dist_to_height"] * self.get_height()

    def get_field_of_view(self) -> float:
        return 2 * math.atan(self.uniforms["focal_dist_to_height"] / 2)

    def get_implied_camera_location(self) -> np.ndarray:
        to_camera = self.get_inverse_camera_rotation_matrix()[2]
        dist = self.get_focal_distance()
        return self.get_center() + dist * to_camera