import numpy as np
import igl
from PyQt5.QtWidgets import QApplication
from PyIGL_viewer import Viewer

# Path to your OBJ file stored in path_to_obj_file 
vertices, faces = igl.read_triangle_mesh(path_to_obj_file)

# Create Qt application and our viewer window
viewer_app = QApplication(["IGL viewer"])
viewer = Viewer()
viewer.show()
viewer.set_column_stretch(0, 1)

# Add a viewer widget to visualize 3D meshes to our viewer window
viewer_widget, _ = viewer.add_viewer_widget(0, 0)
viewer_widget.show()

# Add a screenshot button
def screenshot_function():
    viewer.save_screenshot(os.path.join('screenshot.png'))
viewer.add_ui_button("Take Screenshot", screenshot_function)

# Add a mesh to our viewer widget
# This requires three steps:
# - Adding the mesh vertices and faces
# - Adding a mesh prefab that contains shader attributes and uniform values
# - Adding an instance of our prefab whose position is defined by a model matrix
mesh_index = viewer_widget.add_mesh(vertices, faces)
mesh_prefab_index = viewer_widget.add_mesh_prefab(mesh_index, 'default')
instance_index = viewer_widget.add_mesh_instance(mesh_prefab_index, np.eye(4, dtype='f'))


# Add the wireframe for our mesh 
viewer_widget.add_wireframe(instance_index, line_color=np.array([0.1, 0.1, 0.1]))

# Launch the Qt application
viewer_app.exec()