TinyRenderer doesn't correctly render shadow

[motokiomura]

I use pybullet in sim2real situation, and I randomize some light conditions by using TinyRenderer because OpenGL renderer doesn't allow us to change light conditions as mentioned in #1326.

But when using TinyRenderer, I found that shadow isn't rendered correctly.

import pybullet as p
import matplotlib.pyplot as plt
import numpy as np
import pybullet_data

p.connect(p.GUI)
p.setAdditionalSearchPath(pybullet_data.getDataPath())
p.resetSimulation()

planeId = p.loadURDF('plane.urdf', [0,0,0], [0, 0, -1, 0])
sphereId = p.loadURDF('sphere2red.urdf',[0,0,0],[0, 0, -1, 0],useFixedBase=True, globalScaling=3)

view_matrix = p.computeViewMatrix(
    cameraEyePosition=[-10,0,15],
    cameraTargetPosition=[0,0,0],
    cameraUpVector=[1,0,0]
)
proj_matrix = p.computeProjectionMatrixFOV(
    fov=40, aspect=1,
    nearVal=0.1, farVal=100
)

width =  224
height = 224

(_, _, rgb_px_gl, _, _) = p.getCameraImage(width,height,viewMatrix=view_matrix,projectionMatrix=proj_matrix,shadow=1,renderer=p.ER_BULLET_HARDWARE_OPENGL)
(_, _, rgb_px_tiny, _, _) = p.getCameraImage(width,height,viewMatrix=view_matrix,projectionMatrix=proj_matrix,shadow=1,renderer=p.ER_TINY_RENDERER)

rgb_px_gl = np.array(rgb_px_gl, 'uint8').reshape(width,height, 4)[:, :, :3]
rgb_px_tiny = np.array(rgb_px_tiny, 'uint8').reshape(width,height, 4)[:, :, :3]
plt.imsave("gl.png",rgb_px_gl)
plt.imsave("tiny.png",rgb_px_tiny)

gl.png

tiny.png

Those are rendered images when changing light direction with TinyRenderer

I think shadow condition is important for domain randomization in sim2real situation, so I wonder there is any way to correctly render shadow with TinyRenderer.