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Full Cycle Cross-platform Game Development with SDL, CMAKE and GitHub

Estimated time to read: 10 minutes

This Dojo is focused in training professionals on setting up a full cycle project using SDL, CMAKE and GitHub actions.

Agenda:

  • Introduction (5 minutes): The facilitator introduces the coding dojo and the goal of the session, which is to create a CMake build system for an SDL project using GitHub Actions.
  • Warm-up exercise (10 minutes): A brief exercise is conducted to get participants warmed up and familiar with SDL and CMake.
  • Setting up the project (30 minutes): Participants work in pairs or small groups to clone the SDL project from GitHub and create a CMake build system for it.
  • Adding GitHub Actions (30 minutes): Participants continue to work on their CMake build systems and add GitHub Actions to automate the build and test process.
  • Review and discussion (10 minutes): Participants share their solutions and discuss the various approaches taken to create the CMake build system and implement GitHub Actions.
  • Retrospective (5 minutes): Participants reflect on the session and provide feedback on what went well and what could be improved for future sessions.
  • Closing (5 minutes): The facilitator concludes the session and thanks the participants for their contributions.

Introduction

Warm-up

  • Write down what do you expect from this Dojo here;

Setup

You can either fork Modern CPP Starter Repo (and star it) or create your own from scratch.

Ensure that you have the following software installed in your machine:

  • C++ Compiler. Ex.: GCC(build-essential, and cmake) on Linux, MS Visual Studio on Windows(select C++ and in additional tools, select cmake), Command Line Tools for OSX.
  • Git. Ex.: Gitkraken(free for students);
  • IDE. Ex.: Clion(free for students);
  • CMake. Ex.: cmake-gui, but clion already bundle it for you.

Action

1. Clone.

Clone your repository you created or forked in the last step (Modern CPP Starter Repo);

2. CMake Glob

Edit your CMakeLists.txt to glob your files (naive and powerful approach). Example:

Minimum CMake: 

cmake_minimum_required(VERSION 3.25)
project(MY_PROJECT)
set(CMAKE_CXX_STANDARD 17)
add_executable(mygamename main.cpp)
Add a GLOB to search for four files. 
file(GLOB MY_INCLUDES # Rename this variable
        CONFIGURE_DEPENDS
        ${CMAKE_CURRENT_SOURCE_DIR}/*.h
        ${CMAKE_CURRENT_SOURCE_DIR}/*.hpp
        )

file(GLOB MY_SOURCE # Rename this variable
        CONFIGURE_DEPENDS
        ${CMAKE_CURRENT_SOURCE_DIR}/*.cpp
        ${CMAKE_CURRENT_SOURCE_DIR}/*.c
        )
Then edit your last line to use the result of it as the sources for your executable. 
add_executable(mygamename ${MY_SOURCE} ${MY_INCLUDE})

3. CPM

Add code for the package manager CPM.

Read their example and how do you download it. Optionally, you can download it dynamically, this is the way I prefer.;

4. SDL dependency

Use CPM to download your dependencies. Please refer to this issue comment for an example. If you want to see something already done, check this one;

5. Linking

Link your executable to SDL; 

target_link_libraries(mygamename PUBLIC SDL2)
You can see it in action here. In this example, we include the external cmake file manage that. It is a good practice to do that.

6. Optional: ImGUI

ImGui for debugging interface purposes;

Use CPM to download ImGUI and link it to your library. Example - You can optionally remove the static link if you want. https://github.com/InfiniBrains/SDL2-CPM-CMake-Example/blob/main/main.cpp

Link your executable to IMGUI 

target_link_libraries(mygamename PUBLIC SDL2 IMGUI)

7. It is GAME time!

Copy this example here to your main.cpp if you are going do use ImGUI or just use something like this:

#include <stdio.h>

#include "SDL.h"

int main()
{
    if(SDL_Init(SDL_INIT_VIDEO) != 0) {
        fprintf(stderr, "Could not init SDL: %s\n", SDL_GetError());
        return 1;
    }
    SDL_Window *screen = SDL_CreateWindow("My application",
            SDL_WINDOWPOS_UNDEFINED,
            SDL_WINDOWPOS_UNDEFINED,
            640, 480,
            0);
    if(!screen) {
        fprintf(stderr, "Could not create window\n");
        return 1;
    }
    SDL_Renderer *renderer = SDL_CreateRenderer(screen, -1, SDL_RENDERER_SOFTWARE);
    if(!renderer) {
        fprintf(stderr, "Could not create renderer\n");
        return 1;
    }

    SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
    SDL_RenderClear(renderer);
    SDL_RenderPresent(renderer);
    SDL_Delay(3000);

    SDL_DestroyWindow(screen);
    SDL_Quit();
    return 0;
}

8. Github Actions.

Create folder .github and inside it another one workflows. Inside it create a .yml file.

Here you will code declaratively how your build should proceed. The basic steps are usually: Clone, Cache, Install dependencies, Configure, Build, Test and Release conditionally to branch.

Check and try to reproduce the same thing you see here.

If you are following the Modern CPP Starter Repo, you can explore automated tests. Be my guest and try it.

Review

How far you went? Share your repos here.

Retrospective

Please give me feedbacks in what we did today. If you like or have something to improve, say something in here. Ah! you can always fork this repo, improve it and send a pull request back to this repo.

Closing

Give stars to all repos you saw here as a way to contribute to the continuity of the project. say thanks

Propose a new Dojo and be in touch. Discord