如何控制self.play在特定时间点运行

Question

假设有两个self.play语句，第一个语句从1s开始，我希望秒从一开始正好从3s开始。

目前我使用self.wait来控制步骤：

self.wait(1)
self.play...... # first animation
self.wait(2)    # because 1 + 2 = 3
self.play...... # second animation

但是，因为第一个动画需要一些时间(例如1.5秒)才能完成，所以实际上第二个动画将从1+1.5+2= 4.5s开始。

如何才能让第二个self.play start从一开始就以3s的速度运行？提前谢谢。

Answer 1

你是说这个吗？

class SuccessionExample(Scene):
    def construct(self):
        number_line=NumberLine(x_min=-2,x_max=2)
        triangle=RegularPolygon(3,start_angle=-PI/2)\
                   .scale(0.2)\
                   .next_to(number_line.get_left(),UP,buff=SMALL_BUFF)
        text_1=TextMobject("1")\
               .next_to(number_line.get_tick(-1),DOWN)
        text_2=TextMobject("2")\
               .next_to(number_line.get_tick(0),DOWN)
        text_3=TextMobject("3")\
               .next_to(number_line.get_tick(1),DOWN)
        text_4=TextMobject("4")\
               .next_to(number_line.get_tick(2),DOWN)

        self.add(number_line)
        self.play(ShowCreation(triangle))
        self.wait(0.3)

        self.play(
                    #The move of the triangle starts
                    ApplyMethod(triangle.shift,RIGHT*4,rate_func=linear,run_time=4),

                    AnimationGroup(
                        Animation(Mobject(),run_time=1),#<- one second pause
                        Write(text_1),lag_ratio=1       #<- then start Write animation
                    ),
                    AnimationGroup(
                        Animation(Mobject(),run_time=2),#<- two seconds pause
                        Write(text_2),lag_ratio=1       #<- then start Write animation
                    ),
                    AnimationGroup(
                        Animation(Mobject(),run_time=3),#<- three seconds pause
                        Write(text_3),lag_ratio=1       #<- then start Write animation
                    ),
                    AnimationGroup(
                        Animation(Mobject(),run_time=4),#<- four seconds pause
                        Write(text_4),lag_ratio=1       #<- then start Write animation
                    ),
            )

        self.wait()