3b1b-manim/mobject/functions.py

from __future__ import absolute_import

from constants import *

from mobject.types.vectorized_mobject import VMobject
from utils.config_ops import digest_config


class ParametricFunction(VMobject):
    CONFIG = {
        "t_min" : 0,
        "t_max" : 1,
        "num_anchor_points" : 100,
    }
    def __init__(self, function, **kwargs):
        self.function = function
        VMobject.__init__(self, **kwargs)

    def generate_points(self):
        n_points = 3*self.num_anchor_points - 2
        self.points = np.zeros((n_points, self.dim))
        self.points[:,0] = np.linspace(
            self.t_min, self.t_max, n_points
        )
        #VMobject.apply_function takes care of preserving
        #desirable tangent line properties at anchor points
        self.apply_function(lambda p : self.function(p[0]))

class FunctionGraph(ParametricFunction):
    CONFIG = {
        "color" : YELLOW,
        "x_min" : -FRAME_X_RADIUS,
        "x_max" : FRAME_X_RADIUS,
    }
    def __init__(self, function, **kwargs):
        digest_config(self, kwargs)
        parametric_function = lambda t : t*RIGHT + function(t)*UP
        ParametricFunction.__init__(
            self, 
            parametric_function,
            t_min = self.x_min, 
            t_max = self.x_max,
            **kwargs
        )
        self.function = function

    def get_function(self):
        return self.function