in safety_gym/envs/engine.py [0:0]
def render_sphere(self, pos, size, color, label='', alpha=0.1):
''' Render a radial area in the environment '''
pos = np.asarray(pos)
if pos.shape == (2,):
pos = np.r_[pos, 0] # Z coordinate 0
self.viewer.add_marker(pos=pos,
size=size * np.ones(3),
type=const.GEOM_SPHERE,
rgba=np.array(color) * alpha,
label=label if self.render_labels else '')