implement input and rework window implementation

moved the window variable as a constant in the window module, and
implement more of GLFW logic, including some basic input handling.

src/io/input.c

@@ -0,0 +1,13 @@
+// Copyright (c) 2025 Quinn
+// Licensed under the MIT Licence. See LICENSE for details
+#include "input.h"
+
+#include <GLFW/glfw3.h>
+
+void key_callback(GLFWwindow* win, int key, int scancode, int action, int mods) {
+	(void)win, (void)key, (void)scancode, (void)action, (void)mods; // make the compiler shut up as this is fine
+#ifndef NDEBUG
+	if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS)
+		glfwSetWindowShouldClose(win, 1);
+#endif
+}

src/io/input.h

@@ -0,0 +1,7 @@
+// Copyright (c) 2025 Quinn
+// Licensed under the MIT Licence. See LICENSE for details
+#pragma once
+#include <GLFW/glfw3.h>
+
+void key_callback(GLFWwindow* win, int key, int scancode, int action, int mods);
+

src/io/window.c

@@ -3,21 +3,43 @@
 #include "window.h"
 
 #include <GLFW/glfw3.h>
+#include <assert.h>
 #include <stdlib.h>
+#include "input.h"
 
 // macros for ease of access
 #define WIN_NAME           "MCA Selector Lite"
 #define WIN_DEFAULT_WIDTH  640
 #define WIN_DEFAULT_HEIGHT 480
 
-int window_init(struct renderdat* restrict rdat) {
-	GLFWwindow* const win = glfwCreateWindow(WIN_DEFAULT_WIDTH, WIN_DEFAULT_HEIGHT, WIN_NAME, NULL, NULL);
-	if (win == NULL) return 1;
-	rdat->win = win;
+static GLFWwindow* win = NULL;
+
+int window_init(void) {
+	// initialize the window
+	glfwWindowHint(GLFW_RESIZABLE, GLFW_TRUE);
+	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
+	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
+	glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE); // TODO: read about opengl profiles
+	glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GLFW_TRUE);
+	win = glfwCreateWindow(WIN_DEFAULT_WIDTH, WIN_DEFAULT_HEIGHT, WIN_NAME, NULL, NULL);
+	if (!win) return 1;
+
+	// make the current window the current context
+	glfwMakeContextCurrent(win);
+
+	// configure callbacks
+	glfwSetKeyCallback(win, key_callback);
+	glfwSwapInterval(1); // wait 1 screen update for a redraw a.k.a. "vsync". (not really applicable in this case but eh)
 
 	return 0;
 }
 
-void window_free(struct renderdat* restrict rdat) {
-	glfwDestroyWindow(rdat->win);
+void window_loop(void) {
+	assert(win != NULL);
+
+	while (!glfwWindowShouldClose(win)) {
+		glfwWaitEvents(); // wait till an update has been given
+	}
+
+	glfwDestroyWindow(win);
 }

src/io/window.h

@@ -2,11 +2,5 @@
 // Licensed under the MIT Licence. See LICENSE for details
 #pragma once
 
-#include <GLFW/glfw3.h>
-
-struct renderdat {
-	GLFWwindow* win;
-};
-
-int window_init(struct renderdat* restrict rdat);
-void window_free(struct renderdat* restrict rdat);
+int window_init(void);  // initializes the global window, returns non-zero upon failure
+void window_loop(void); // performs the window updates