Why procedural models in Ursina are shaded differently

Question

I can't figure out how to make Ursina procedural models look the same as mesh-based models.

from ursina import *
from ursina import shaders

app = Ursina()

L1 = DirectionalLight(color=color.white)
L1.setHpr((0, 0, 0))

e = Entity(model=Cube(), x=-2, color=color.green)
e = Entity(model='cube', x=2, color=color.red)

_ed = EditorCamera(rotation_speed = 200, panning_speed=200)

app.run()

Produces the following result:

Green and red cubes but green is black"

What am I missing? Why is the green cube not lit by the directional light?

I have tried using different shaders included in Ursina but it did not solve the problem.

Answer 1

Are you confused by the black color of the face on the right cube? Your light source is a directional projector (lamp). You illuminated one straight face on the red cube, but the light does not reach the green cube and the cube is black. Check:

from ursina import *
app = Ursina()
light = AmbientLight()  
light.rotation = Vec3(0, 0, 0)  # Setup light
e = Entity(model=Cube(), x=-2, color=color.green)
e = Entity(model='cube', x=2, color=color.red)
app.run()

you don't need to flip the normals, you need to set the light

Answer 2

Adding a call to generate_normals() seems to fix the problem:

e = Entity(model=Cube(), x=-2, color=color.green)
e.model.generate_normals()