I tried to merge all cubes in Mesh() function, but it didnt worked for me...

[DrFrankNorton]

I tried to merge all cubes in Mesh() function, but it didnt worked for me...

[DrFrankNorton]

Edit:

I changed the code, is this:

from ursina import *
import math
app = Ursina()
window.borderless = False
window.exit_button.visible = False
window.fps_counter.enabled = True
window.entity_counter.enabled = False
window.collider_counter.enabled = False
renderdistance=10
chunkSize=5
cubes = {}
terrain = Entity(model=None, collider=None)
def g(x,y,z):
    cubes[(x+renderdistance, z+renderdistance, 0)] = Entity(parent=terrain, model='cube', texture='dirt', position=(x, y, z), scale=(1,5,1))
    cubes[(x+renderdistance, z+renderdistance, 1)] = Entity(parent=terrain, model='cube', texture='grass_side', position=(x, y + 3, z), scale=(1.01,1,1.01))
    cubes[(x+renderdistance, z+renderdistance, 2)] = Entity(parent=terrain, model='cube', texture='grass', position=(x, y + 3, z), scale=(1,1.01,1))
def getSurface(i,k):
    return int((sin(i/5)+cos(k/5))*5)
for i in range(-renderdistance,renderdistance):
    for k in range(-renderdistance,renderdistance):
        surface=getSurface(i,k)
        g(i,surface,k)
walkspeed=4
rotspeed=90
mouse_sensitivity = Vec2(100, 100)
window.color = color.rgb(0,127,255)
camera.x=0
camera.y=0
camera.z=0
camera.fov=75
def calcular_distancia(x1,y1,z1,x2,y2,z2):
    return ((x1-x2)**2+(y1-y2)**2+(z1-z2)**2)**0.5
def regenerar():
    for i in range(-renderdistance,renderdistance):
        for k in range(-renderdistance,renderdistance):
            surface=getSurface(int(i+camera.x),int(k+camera.z))
            cubes[(i+renderdistance, k+renderdistance, 0)].x=int(i+camera.x)
            cubes[(i+renderdistance, k+renderdistance, 0)].y=int(surface)
            cubes[(i+renderdistance, k+renderdistance, 0)].z=int(k+camera.z)
            cubes[(i+renderdistance, k+renderdistance, 1)].x=int(i+camera.x)
            cubes[(i+renderdistance, k+renderdistance, 1)].y=int(surface+3)
            cubes[(i+renderdistance, k+renderdistance, 1)].z=int(k+camera.z)
            cubes[(i+renderdistance, k+renderdistance, 2)].x=int(i+camera.x)
            cubes[(i+renderdistance, k+renderdistance, 2)].y=int(surface+3)
            cubes[(i+renderdistance, k+renderdistance, 2)].z=int(k+camera.z)
prev_position_x=camera.x
prev_position_y=camera.y
prev_position_z=camera.z
def update():
    global prev_position_x, prev_position_y, prev_position_z
    if held_keys['w'] and mouse.locked == True and mouse.visible == False:
        camera.position += (math.sin(math.radians(camera.rotation_y)) * time.dt * walkspeed, 0, math.cos(math.radians(camera.rotation_y)) * time.dt * walkspeed)
    if held_keys['s'] and mouse.locked == True and mouse.visible == False:
        camera.position -= (math.sin(math.radians(camera.rotation_y)) * time.dt * walkspeed, 0, math.cos(math.radians(camera.rotation_y)) * time.dt * walkspeed)
    if held_keys['a'] and mouse.locked == True and mouse.visible == False:
        camera.position -= (math.cos(math.radians(camera.rotation_y)) * time.dt * walkspeed, 0, -math.sin(math.radians(camera.rotation_y)) * time.dt * walkspeed)
    if held_keys['d'] and mouse.locked == True and mouse.visible == False:
        camera.position += (math.cos(math.radians(camera.rotation_y)) * time.dt * walkspeed, 0, -math.sin(math.radians(camera.rotation_y)) * time.dt * walkspeed)
    if mouse.left:
        mouse.locked = True
        mouse.visible = False
    if held_keys['escape']:
        mouse.locked = False
        mouse.visible = True
    if mouse.locked == True and mouse.visible == False:
        camera.rotation_y += mouse.velocity[0] * mouse_sensitivity[1]
        camera.rotation_x -= mouse.velocity[1] * mouse_sensitivity[0]
        camera.rotation_x = clamp(camera.rotation_x, -90, 90)
        for i in range(0,10):
            if getSurface(camera.x,camera.z) + 6 + 0.1 < camera.y:
                camera.y-=0.1
            else:
                if getSurface(camera.x,camera.z) + 6 - 0.1 > camera.y:
                    camera.y+=0.1
    if calcular_distancia(prev_position_x,0,prev_position_z,camera.x,0,camera.z)>chunkSize:
        regenerar()
        prev_position_x=camera.x
        prev_position_y=camera.y
        prev_position_z=camera.z
app.run()