handle window exits more gracefully and appropriately.

src/io/render.c

@@ -2,9 +2,8 @@
  * Licensed under the MIT Licence. See LICENSE for details */
 #include "render.h"
 
-#include <glad/gl.h>
-
 #include <GLFW/glfw3.h>
+#include <glad/gl.h>
 #include <stdint.h>
 
 #include "../error.h"
@@ -80,3 +79,12 @@ void render_update(GLFWwindow *win) {
 	glBindVertexArray(vao);
 	glDrawArrays(GL_POINTS, 0, VERTC);
 }
+
+void render_free(void) {
+	glDeleteVertexArrays(1, &vao);
+	glDeleteBuffers(1, &vbo);
+	glDeleteProgram(pipe);
+	vbo = 0;
+	vao = 0;
+	pipe = 0;
+}

src/io/render.h

@@ -2,9 +2,9 @@
  * Licensed under the MIT Licence. See LICENSE for details */
 #pragma once
 
-#include <glad/gl.h>
-
 #include <GLFW/glfw3.h>
+#include <glad/gl.h>
 
 int render_init(void);
 void render_update(GLFWwindow *win);
+void render_free(void);

src/io/window.c

@@ -69,5 +69,13 @@ void window_loop(void) {
 		glfwSwapBuffers(win);
 	}
 
-	glfwDestroyWindow(win);
+void window_close(void) {
+	assert(win);
+	glfwSetWindowShouldClose(win, 1);
+}
+
+void window_free(void) {
+	glfwDestroyWindow(win);
+	render_free();
+	win = NULL;
 }

src/io/window.h

@@ -2,5 +2,18 @@
  * Licensed under the MIT Licence. See LICENSE for details */
 #pragma once
 
-int window_init(void);  // initializes the global window, returns non-zero upon failure
+/* Set up the window, enabling OpenGL, and
-void window_loop(void); // performs the window updates
+ * configuring the settings that are needed.
+ * Returns `0` upon success, otherwise `1`. */
+int window_init(void);
+
+/* Calls the update loop for the window.
+ * This function does not exit until the window does. */
+void window_loop(void);
+
+/* Requests the window to close (gracefully). */
+void window_close(void);
+
+/* Cleans up all resources held by the window.
+ * If the window is still open, it will be terminated. */
+void window_free(void);

src/main.c

@@ -14,6 +14,10 @@ static void error_callback(int err, const char *const msg) {
 }
 
 static void quit(void) {
+	window_free();
+
+	/* terminates GLFW; destroying any
+	 * remaining windows, or other resources held by GLFW. */
 	glfwTerminate();
 }
 
@@ -30,7 +34,7 @@ int main(int argc, char **argv) {
 		fatal("failed to initialise!");
 
 	window_loop();
-	quit();
+	window_free();
 
 	// return success, since some architectures do not follow 0=success
 	return EXIT_SUCCESS;