Add some input and make the screen a different color.

src/main.cc

@@ -3,6 +3,7 @@
 #include <GLFW/glfw3.h>
 
 void framebuffer_size_callback(GLFWwindow* window, int width, int height);
+void process_input(GLFWwindow* window);
 
 int main() {
 	glfwInit();
@@ -40,6 +41,14 @@ int main() {
 
 	// Create a render loop, which keeps the program open until glfw tells the loop that the window should close.
 	while (!glfwWindowShouldClose(window)) {
+		// Process input.
+		process_input(window);
+		
+		// Set the GL state to use this color when clearing the screen.
+		glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
+		// Clear the screen and use the color from the state.
+		glClear(GL_COLOR_BUFFER_BIT);
+
 		// This swaps completely drawn frames from the "second buffer" to the front one which is displayed on the screen.
 		glfwSwapBuffers(window);
 		// Check if any events are triggered.
@@ -54,3 +63,9 @@ void framebuffer_size_callback(GLFWwindow* window, int width, int height) {
 	// Tell OpenGL the size of the rendering window.
 	glViewport(0, 0, width, height);
 }
+
+void process_input(GLFWwindow* window) {
+	if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS) {
+		glfwSetWindowShouldClose(window, true);
+	}
+}