feat: example loading nrrd

Author: seankmartin

examples/load_nrrd.py

@@ -0,0 +1,55 @@
+import argparse
+import webbrowser
+import neuroglancer
+import neuroglancer.cli
+import nrrd
+from pathlib import Path
+
+HERE = Path(__file__).parent
+NRRD_FILE_PATH = HERE / "volume1.nrrd"
+
+
+def add_image_layer(state):
+    readdata, header = nrrd.read(NRRD_FILE_PATH)
+    scales = [header["space directions"][i][i] for i in range(3)]
+    dimensions = neuroglancer.CoordinateSpace(
+        names=["x", "y", "z"], units="um", scales=scales
+    )
+    data = readdata
+    local_volume = neuroglancer.LocalVolume(data, dimensions)
+    state.layers.append(
+        name="image",
+        layer=neuroglancer.ImageLayer(
+            source=local_volume,
+            volume_rendering_mode="ON",
+            volume_rendering_depth_samples=400,
+        ),
+        shader="""
+#uicontrol invlerp normalized
+void main() {
+    float val = normalized();
+    emitRGBA(vec4(val, val, val, val));
+    }
+    """,
+    )
+    state.layout = "3d"
+
+
+def launch_nglancer():
+    ap = argparse.ArgumentParser()
+    neuroglancer.cli.add_server_arguments(ap)
+    args = ap.parse_args()
+    neuroglancer.cli.handle_server_arguments(args)
+    viewer = neuroglancer.Viewer()
+    return viewer
+
+
+def main():
+    viewer = launch_nglancer()
+    with viewer.txn() as s:
+        add_image_layer(s)
+    webbrowser.open_new(viewer.get_viewer_url())
+
+
+if __name__ == "__main__":
+    main()