transparency attribute is exported

utils/exporters/blender/addons/io_three/exporter/material.py

@@ -43,6 +43,9 @@ class Material(base_classes.BaseNode):
 
         self[constants.BLENDING] = api.material.blending(self.node)
 
+        if api.material.transparent(self.node):
+            self[constants.TRANSPARENT] = True
+
         self[constants.DEPTH_TEST] = api.material.depth_test(self.node)
 
         self[constants.DEPTH_WRITE] = api.material.depth_write(self.node)