An implementation of the A-star path finding algorithm using SDL2 to visualize the path. Based on the A-star tutorial by OneLoneCoder.

Use brew to install SDL2 (SDL2: stable 2.0.12) From the SDL2AStar directory follow the following steps to build the project

mkdir build
cd build
cmake ..
make

the application a-star will be in the build/a-star directory.

cd a-star
./a-star

The following window will open:

This shows the grid of nodes, how each node is connected to the neighbouring nodes, the green start node, the red end node and the path from the start node to the end node. All of the nodes are a faded blue colour since they have all been tested by the A* algorithm.

The position of the green starting node can be changed by holding the shift key and clicking on the new start node.

Similarly, the position of the ending node can be changed by holding the control key and clicking on the new end node.

Obstacles can be added by clicking on empty nodes, turning them black. The path will need to go around obstacles.

Note the behaviour of the path with respect to diagonally placed obstacles.

Finally, nodes that are not reachable by the search algorithm are colored dark blue.

It is possible for the A* to fail, in this case no path will be displayed.

• It is possible to change the code to implement Dijkstra's search algorithm, I'll add a switch in the empty space of the window to do that.
• The default is to search all available nodes, even when the end node has been found, it is possible to stop the search when we find the end node.
• The code is a bit messy, I need to do some refactoring to make it a bit easier to follow.

The following applications were used to create and build this demo.

• macOS Catalina(Version 10.15.4)
• CLion 2020.1.1, c++17,
• cmake 3.17.2
• GNU Make 3.81.

• JetBrains CLion
• SDL2 - Simple Direct Media Layer

I'd be very happy to hear your comments and suggestions for this project.

• Rich Nistuk - Initial work - rnistuk

• javidx9 OneLoneCoder - A great educational youTube channel, javidx9 has many great coding tutorials and I based this project on his Path Planning - A* (A-Star) tutorial video.
  OneLoneCoder community
  OneLonecoder Github
• A-star on Wikipedia