Transform Types

from_copy

class EquationScene1(Scene):
    def construct(self):

        x, y, _1, _3, eq, mn = MathTex("x", "y", "1", "3", "=", "-")

        x.set_color(BLUE)
        y.set_color(GREEN)

        tex1 = MathTex(       x,                 eq,  [ Term(y, _3), "+", _1 ]); eq.save_x()
        tex2 = MathTex(     [ x, mn, _1 ],       eq,    Term(y, _3)           )
        tex3 = MathTex(Root([ x, mn, _1 ], _3),  eq,         y                )
        tex4 = MathTex(     tex3.RHS,            eq,    tex3.LHS              )

        group = VGroup(tex1, tex2, tex3, tex4).arrange(DOWN, buff=MED_LARGE_BUFF)
        [ tex[1].restore_x() for tex in group ]

        self.add(tex1)
        self.play(TransformInStages.from_copy(tex1, tex2))
        self.play(TransformInStages.from_copy(tex2, tex3))
        self.play(TransformInStages.from_copy(tex3, tex4))

replacement_transform

class EquationScene2(Scene):
    def construct(self):

        x, y, _1, _3, eq, mn = MathTex("x", "y", "1", "3", "=", "-")

        x.set_color(BLUE)
        y.set_color(GREEN)

        tex1 = MathTex(       x,                 eq,  [ Term(y, _3), "+", _1 ]); eq.save_x()
        tex2 = MathTex(     [ x, mn, _1 ],       eq,    Term(y, _3)           )
        tex3 = MathTex(Root([ x, mn, _1 ], _3),  eq,         y                )
        tex4 = MathTex(     tex3.RHS,            eq,    tex3.LHS              )

        group = VGroup(tex1, tex2, tex3, tex4)
        [ tex[1].restore_x() for tex in group ]

        self.add(tex1)
        self.play(TransformInStages.replacement_transform(tex1, tex2))
        self.play(TransformInStages.replacement_transform(tex2, tex3))
        self.play(TransformInStages.replacement_transform(tex3, tex4))

progress

class EquationScene3(Scene):
    def construct(self):

        x, y, _1, _3, eq, mn = MathTex("x", "y", "1", "3", "=", "-")

        x.set_color(BLUE)
        y.set_color(GREEN)


        tex = MathTex(       x,                  eq,  [ Term(y, _3), "+", _1 ]); eq.save_x()
        self.add(tex)

        tex.terms =  [      [ x, mn, _1 ],       eq,    Term(y, _3)           ]; eq.restore_x()
        self.play(TransformInStages.progress(tex))

        tex.terms =  [ Root([ x, mn, _1 ], _3),  eq,         y                ]; eq.restore_x()
        self.play(TransformInStages.progress(tex))

        tex.terms =  [      tex.RHS,              eq,     tex.LHS             ]; eq.restore_x()
        self.play(TransformInStages.progress(tex))