IO2D Starter Code

You are now ready to look at the starter code that you'll be using for the project. This code comes from a map rendering example in the Github repo for the 2D Graphics Library, IO2D. You will be extending the code to search for and display a path between two points on the map.

The process that you go through to develop your project will similar to the process you might go through to use or extend other open source code. By the time you finish this project, you will be ready to start working on your own projects!

We've modified the IO2D example code slightly to help you get started with the project. In particular, we included some class stubs that will help you extend the existing classes, and we added a few short plotting functions.

Code Structure

The starter code for the project can be found here. This code is already loaded into a workspace, and you will not need to download or run the code locally to do the project. It may be a good idea to open the repository in a different tab and follow along as you read through the descriptions below, however. In the repo, you should see the following five directories:

• cmake

  This directory contains some CMakeLists.txt files that are needed for the project to find necessary libraries. You will not need to work with this directory for this project.

• instructions

  This directory contains a set of markdown instruction files for the exercises. Again, you will not need to work directly with the files here, but each set of instructions will be displayed in the terminal workspace for the appropriate exercise as you work on the project.

• src

  The source code for the project is contained here, and this is where you will be doing all of the project work. See below for more information about the contents of this directory.

• test

  This directory contains unit tests for various exercises, implemented using the Google Test framework. As you are developing your code, it may be helpful to look at the relevant test in this directory to see the expected answer and corresponding code. If your code fails a test, the console will tell you which file contains the failing test.

• thirdparty

  This directory contains third party libraries that have been included with this project. You will not need to work directly with this code.

The src Directory

Let's have a closer look at the src directory, since this is where you will be doing most of the work.

main.cpp

The main.cpp controls the flow of the program, accomplishing four primary tasks:

• The OSM data is read into the program.
• A RouteModel object is created to store the OSM data in usable data structures.
• A RoutePlanner object is created using the RouteModel. This planner will eventually carry out the A* search on the model data and store the search results in the RouteModel.
• The RouteModel data is rendered using the IO2D library.
  Have a look at the video below for a brief overview of this file:

model.h and model.cpp

These files come from the IO2D example code. They are used to define the data structures and methods that read in and store OSM data. OSM data is stored in a Model class which contains nested structs for Nodes, Ways, Roads, and other OSM objects. You will be extending this class in your project. Have a look at the video below for an overview of the code in these two files.

render.h and render.cpp

These files from the IO2D example code take model data and render it on a map. We have modified these files slightly to include three extra methods which render the start point, end point, and path from the A* search. You won't need to work too much with these files, but you will uncomment the code to render the results of your search at some point. Have a look at the video below for a brief overview of the file code.

route_model.h and route_model.cpp

These files contain class stubs which will be used to extend the Model and Node data structures from model.h and model.cpp using class inheritance. Remember that inheritance in this case will allow you to use all of the public methods and attributes of the Model and Node classes in the derived classes. You will be filling out the classes in route_model.h and route_model.cpp over the course of your project.

Have a look at the video below for a brief overview of the contents of these files.

route_planner.h and route_planner.cpp

These files contain a class stub for a RoutePlanner class which accepts a RouteModel along with start and end coordinates. The RouteModel data, along with the start and end points will be used for A* search, which will be implemented in these files. Have a look a the video below for a brief overview of the contents.