-Fixed height fog (was broken)

-Make sure materials are named in OBJ importer, so they can be saved outside as resources.

drivers/gles3/shaders/scene.glsl

@@ -2048,7 +2048,7 @@ FRAGMENT_SHADER_CODE
 
 		if (fog_height_enabled) {
 			float y = (camera_matrix * vec4(vertex,1.0)).y;
-			fog_amount = max(fog_amount,pow(1.0-smoothstep(fog_height_min,fog_height_max,y),fog_height_curve));
+			fog_amount = max(fog_amount,pow(smoothstep(fog_height_min,fog_height_max,y),fog_height_curve));
 		}
 
 		float rev_amount = 1.0 - fog_amount;

editor/import/resource_importer_obj.cpp

@@ -58,6 +58,7 @@ static Error _parse_material_library(const String &p_path, Map<String, Ref<Spati
 
 			current_name = l.replace("newmtl", "").strip_edges();
 			current.instance();
+			current->set_name(current_name);
 			material_map[current_name] = current;
 		} else if (l.begins_with("Ka ")) {
 			//uv

editor/import/resource_importer_scene.cpp

@@ -952,7 +952,10 @@ void ResourceImporterScene::_make_external_resources(Node *p_node, const String
 
 							for (int i = 0; i < mesh->get_surface_count(); i++) {
 								mat = mesh->surface_get_material(i);
-								if (!mat.is_valid() || mat->get_name() == "")
+
+								if (!mat.is_valid())
+									continue;
+								if (mat->get_name() == "")
 									continue;
 
 								if (!p_materials.has(mat)) {