Add initial app.py for Streamlit

Author: pgleeson

app.py

@@ -0,0 +1,48 @@
+import pyvista as pv
+import sys
+
+st_mode = "-gui" not in sys.argv
+
+print("Starting it all...")
+
+if st_mode:
+    import streamlit as st
+
+    st.set_page_config(layout="wide")
+
+    from stpyvista.utils import start_xvfb
+
+    if "IS_XVFB_RUNNING" not in st.session_state:
+        start_xvfb()
+        st.session_state.IS_XVFB_RUNNING = True
+
+    st.title("OpenWorm 3D Viewer")
+
+
+## Initialize a plotter object
+plotter = pv.Plotter(window_size=[800, 600])
+
+print("Read objs...")
+
+plotter.add_axes()
+plotter.enable_mesh_picking(show_message=True)
+
+sphere = pv.Sphere(end_theta=90)
+plotter.add_mesh(sphere)
+
+## Final touches
+plotter.view_isometric()
+# plotter.add_scalar_bar()
+plotter.background_color = "white"
+
+print("Created the scene...")
+
+if st_mode:
+    ## Pass a key to avoid re-rendering at each page change
+    if False:
+        from stpyvista import stpyvista
+
+        stpyvista(plotter, key="pv_cube")
+    pass
+else:
+    plotter.show()