Allow add two or more ImageMobjects and TextureSurfaces

[zhuanvi]

Motivation

Adding two or more images with ImageMobject showing the recent image in the Scene.

The same problem also occurs in TextureSurface, and this PR is meant to solve this problem.

Proposed changes

• image_mobject.py
• surface.py
• shader_wrapper.py

Test

Code:

from manimlib import *


class Video(Scene):
    
    def construct(self):
        
        image_file1 = "resources/barter-1.png"
        image_file2 = "resources/measure.png"
        image_file3 = "resources/Thales.jpg"
        image_file4 = "resources/Oheaviside.jpg"
        
        im1 = ImageMobject(image_file1)
        im2 = ImageMobject(image_file2)
        
        im1.set_width(3)
        im2.set_width(3)
        
        self.play(FadeIn(im1))
        self.play(im1.animate.shift(3*LEFT))
        
        self.play(FadeIn(im2))
        self.play(im2.animate.shift(3*RIGHT))
        
        
        surf1 = Sphere(radius=1)
        surf2 = Sphere(radius=1)
        
        surf2.move_to(np.array([2,3,1]))
        
        ts1 = TexturedSurface(surf1,image_file3)
        ts2 = TexturedSurface(surf2,image_file4)
        self.play(ShowCreation(ts1))
        self.play(ShowCreation(ts2))
        
        frame = self.camera.frame
        frame.set_euler_angles(
            theta=-30 * DEGREES,
            phi=70 * DEGREES,
        )
        
        frame.add_updater(lambda m, dt: m.increment_theta(-0.1 * dt))
        self.wait(5)

Result:

https://github.com/3b1b/manim/assets/15604323/6d222864-99dc-4ba9-b7ec-6cc469ec9807

[bengioe]

FWIW applying this patch solved another problem for me where when rendering multiple images some erroneous textured triangles would appear between images (as if the batching went wrong within OpenGL).