Add OpenGL and GLFW dependencies + example

CMakeLists.txt

@@ -3,4 +3,11 @@ project(ecsgame)
 
 set(CMAKE_CXX_STANDARD 17)
 
-add_executable(ecsgame main.cpp)
+find_package(OpenGL REQUIRED)
+find_package(glfw3 REQUIRED)
+
+add_executable(ecsgame main.cpp)
+
+include_directories(${OPENGL_INCLUDE_DIRS})
+
+target_link_libraries(ecsgame ${OPENGL_LIBRARY} glfw)

main.cpp

@@ -1,11 +1,12 @@
 #include <iostream>
 #include "ECS.h"
+#include <GLFW/glfw3.h>
 
 using namespace ECS;
 
-struct Position
-{
+struct Position {
     Position(float x, float y, float z) : x(x), y(y), z(z) {}
+
     Position() : x(0.f), y(0.f), z(0.f) {}
 
     float x;
@@ -13,19 +14,16 @@ struct Position
     float z;
 };
 
-class GravitySystem : public EntitySystem
-{
+class GravitySystem : public EntitySystem {
 public:
-    GravitySystem(float amount)
-    {
+    GravitySystem(float amount) {
         gravityAmount = amount;
     }
 
     virtual ~GravitySystem() {}
 
-    virtual void tick(World* world, float deltaTime) override
-    {
-        world->each<Position>([&](Entity* ent, ComponentHandle<Position> position) {
+    virtual void tick(World *world, float deltaTime) override {
+        world->each<Position>([&](Entity *ent, ComponentHandle<Position> position) {
             position->y += gravityAmount * deltaTime;
         });
     }
@@ -35,10 +33,10 @@ private:
 };
 
 int main() {
-    World* world = World::createWorld();
+    World *world = World::createWorld();
     world->registerSystem(new GravitySystem(-9.8f));
 
-    Entity* ent = world->create();
+    Entity *ent = world->create();
     ent->assign<Position>(0.f, 0.f, 0.f); // assign() takes arguments and passes them to the constructor
 
     world->tick(1.0f);
@@ -46,5 +44,35 @@ int main() {
     ComponentHandle<Position> pos = ent->get<Position>();
 
     std::cout << "y position after tick: " << pos->y << std::endl;
+
+    GLFWwindow *window;
+
+    /* Initialize the library */
+    if (!glfwInit())
+        return -1;
+
+    /* Create a windowed mode window and its OpenGL context */
+    window = glfwCreateWindow(640, 480, "Hello World", NULL, NULL);
+    if (!window) {
+        glfwTerminate();
+        return -1;
+    }
+
+    /* Make the window's context current */
+    glfwMakeContextCurrent(window);
+
+    /* Loop until the user closes the window */
+    while (!glfwWindowShouldClose(window)) {
+        /* Render here */
+        glClear(GL_COLOR_BUFFER_BIT);
+
+        /* Swap front and back buffers */
+        glfwSwapBuffers(window);
+
+        /* Poll for and process events */
+        glfwPollEvents();
+    }
+
+    glfwTerminate();
     return 0;
 }