class Equation:

    def __init__(self, xf, yf, cf=(255,255,255), wf=1):
        self.xf = xf
        self.yf = yf
        self.cf = cf
        self.wf = wf

    def _xf(self, t):
        if callable(self.xf):
            return self.xf(t)
        else:
            return t

    def _yf(self, t):
        if callable(self.yf):
            return self.yf(t)
        else:
            return t

    def _cf(self, t, r):
        if callable(self.cf):
            return self.cf(t, r)
        else:
            return self.cf

    def _wf(self, t, r):
        if callable(self.wf):
            return self.wf(t, r)
        else:
            return self.wf

    def plot(self, r=(0, 12, 0.1), scale=(1,1)):
        t = r[0]
        prev_x = self._xf(t)
        prev_y = self._yf(t)
        while t <= r[1]:
            x = self._xf(t)
            y = self._yf(t)
            c = self._cf(t, r)
            w = self._wf(t, r)
            yield (
                int(prev_x * scale[0]),
                int(prev_y * scale[1]),
                int(x * scale[0]),
                int(y * scale[1]),
                c,
                w,
            )
            prev_x, prev_y = x, y
            t += r[2]