planning: add util method to convert data from world coirdinate to re…

…lative coord

modules/planning/common/util/BUILD

@@ -36,4 +36,15 @@ cc_library(
     ],
 )
 
+cc_library(
+    name = "math_util_lib",
+    hdrs = ["math_util.h"],
+    copts = [
+        "-DMODULE_NAME=\\\"planning\\\"",
+    ],
+    deps = [
+        "//cyber/common:log",
+        "//modules/common/util:map_util",
+    ],
+)
 cpplint()

modules/planning/common/util/math_util.h

@@ -0,0 +1,44 @@
+/******************************************************************************
+ * Copyright 2020 The Apollo Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *****************************************************************************/
+#pragma once
+
+#include "modules/common/math/math_utils.h"
+
+namespace apollo {
+namespace planning {
+namespace util {
+
+// Helper function to convert world coordinates to relative coordinates
+// around the obstacle of interest.
+std::pair<double, double> WorldCoordToObjCoord(
+    std::pair<double, double> input_world_coord,
+    std::pair<double, double> obj_world_coord, double obj_world_angle) {
+  double x_diff = input_world_coord.first - obj_world_coord.first;
+  double y_diff = input_world_coord.second - obj_world_coord.second;
+  double rho = std::sqrt(x_diff * x_diff + y_diff * y_diff);
+  double theta = std::atan2(y_diff, x_diff) - obj_world_angle;
+
+  return std::make_pair(std::cos(theta) * rho, std::sin(theta) * rho);
+}
+
+double WorldAngleToObjAngle(double input_world_angle,
+                            double obj_world_angle) {
+  return apollo::common::math::NormalizeAngle(input_world_angle - obj_world_angle);
+}
+
+}  // namespace msf
+}  // namespace localization
+}  // namespace apollo