1 files changed, 205 insertions, 0 deletions

diff --git a/app/src/app.c b/app/src/app.c
new file mode 100644
index 0000000..b6d10ca
--- /dev/null
+++ b/app/src/app.c
@@ -0,0 +1,205 @@
+#include <gfx/app.h>
+
+#include <GLFW/glfw3.h>
+#include <log/log.h>
+#include <timer.h>
+
+#include <assert.h>
+#include <stdlib.h>
+
+/// Application state.
+typedef struct GfxApp {
+  GfxAppState*    app_state;
+  GfxAppCallbacks callbacks;
+  int             max_fps;
+  double          update_delta_time;
+  GLFWwindow*     window;
+} GfxApp;
+
+/// Storing the application state in a global variable so that we can call the
+/// application's callbacks from GLFW callbacks.
+static GfxApp g_gfx_app;
+
+/// Called by GLFW when the window is resized.
+static void on_resize(GLFWwindow* window, int width, int height) {
+  (*g_gfx_app.callbacks.resize)(g_gfx_app.app_state, width, height);
+}
+
+/// Run the application's main loop.
+static void loop(GfxApp* app) {
+  assert(app);
+  assert(app->window);
+
+  const time_delta min_frame_time =
+      app->max_fps > 0 ? sec_to_time_delta(1.0 / (double)(app->max_fps)) : 0;
+  const time_delta update_dt   = sec_to_time_delta(app->update_delta_time);
+  time_delta       time        = 0;
+  time_delta       time_budget = 0;
+  Timer            timer       = timer_make();
+
+  // Warm up the update to initialize the application's state.
+  (*app->callbacks.update)(
+      app->app_state, time_delta_to_sec(time), time_delta_to_sec(update_dt));
+
+  // Warm up the rendering before entering the main loop. A renderer can
+  // compile shaders and do other initialization the first time it renders a
+  // scene.
+  (*app->callbacks.render)(app->app_state);
+  glfwSwapBuffers(app->window);
+
+  timer_start(&timer);
+  while (!glfwWindowShouldClose(app->window)) {
+    timer_tick(&timer);
+    time_budget += timer.delta_time;
+
+    while (time_budget >= update_dt) {
+      (*app->callbacks.update)(
+          app->app_state, time_delta_to_sec(time),
+          time_delta_to_sec(update_dt));
+
+      time += update_dt;
+      time_budget -= update_dt;
+    }
+
+    (*app->callbacks.render)(app->app_state);
+    glfwSwapBuffers(app->window);
+    glfwPollEvents();
+
+    const time_point frame_end  = time_now();
+    const time_delta frame_time = time_diff(timer.last_tick, frame_end);
+    if ((min_frame_time > 0) && (frame_time < min_frame_time)) {
+      time_sleep(min_frame_time - frame_time);
+    }
+  }
+}
+
+bool gfx_app_run(const GfxAppDesc* desc, const GfxAppCallbacks* callbacks) {
+  assert(desc);
+  assert(callbacks);
+
+  bool success = false;
+
+  g_gfx_app.app_state         = desc->app_state;
+  g_gfx_app.callbacks         = *callbacks;
+  g_gfx_app.max_fps           = desc->max_fps;
+  g_gfx_app.update_delta_time = desc->update_delta_time;
+  g_gfx_app.window            = 0;
+
+  if (!glfwInit()) {
+    LOGE("glfwInit() failed");
+    return false;
+  }
+
+  const int major = 4;
+  const int minor = 4;
+  glfwWindowHint(GLFW_CLIENT_API, GLFW_OPENGL_API);
+  glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, major);
+  glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, minor);
+  glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
+  glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GLFW_TRUE);
+  // TODO: Test antialiasing later on.
+  // glfwWindowHint(GLFW_SAMPLES, 4);
+
+  const char* title = desc->title ? desc->title : "Gfx Application";
+
+  g_gfx_app.window =
+      glfwCreateWindow(desc->width, desc->height, title, NULL, NULL);
+  if (!g_gfx_app.window) {
+    LOGE("glfwCreateWindow() failed");
+    goto cleanup;
+  }
+  glfwMakeContextCurrent(g_gfx_app.window);
+
+  // Initialize the application's state before setting any callbacks.
+  if (!(*g_gfx_app.callbacks.init)(
+          g_gfx_app.app_state, desc->argc, desc->argv)) {
+    LOGE("Failed to initialize application");
+    goto cleanup;
+  }
+
+  // Trigger an initial resize for convenience.
+  (*g_gfx_app.callbacks.resize)(g_gfx_app.app_state, desc->width, desc->height);
+
+  // Set GLFW callbacks now that the application has been initialized.
+  glfwSetWindowSizeCallback(g_gfx_app.window, on_resize);
+
+  loop(&g_gfx_app);
+
+  (*g_gfx_app.callbacks.shutdown)(g_gfx_app.app_state);
+
+  success = true;
+
+cleanup:
+  if (g_gfx_app.window) {
+    glfwDestroyWindow(g_gfx_app.window);
+  }
+  glfwTerminate();
+  return success;
+}
+
+void gfx_app_get_mouse_position(double* x, double* y) {
+  glfwGetCursorPos(g_gfx_app.window, x, y);
+}
+
+static int to_glfw_key(Key key);
+
+bool gfx_is_key_pressed(Key key) {
+  return glfwGetKey(g_gfx_app.window, to_glfw_key(key)) == GLFW_PRESS;
+}
+
+static int to_glfw_key(Key key) {
+  switch (key) {
+  case KeyA:
+    return GLFW_KEY_A;
+  case KeyB:
+    return GLFW_KEY_B;
+  case KeyC:
+    return GLFW_KEY_C;
+  case KeyD:
+    return GLFW_KEY_D;
+  case KeyE:
+    return GLFW_KEY_E;
+  case KeyF:
+    return GLFW_KEY_F;
+  case KeyG:
+    return GLFW_KEY_G;
+  case KeyH:
+    return GLFW_KEY_H;
+  case KeyI:
+    return GLFW_KEY_I;
+  case KeyJ:
+    return GLFW_KEY_J;
+  case KeyK:
+    return GLFW_KEY_K;
+  case KeyL:
+    return GLFW_KEY_L;
+  case KeyM:
+    return GLFW_KEY_M;
+  case KeyN:
+    return GLFW_KEY_N;
+  case KeyO:
+    return GLFW_KEY_O;
+  case KeyP:
+    return GLFW_KEY_P;
+  case KeyQ:
+    return GLFW_KEY_Q;
+  case KeyR:
+    return GLFW_KEY_R;
+  case KeyS:
+    return GLFW_KEY_S;
+  case KeyT:
+    return GLFW_KEY_T;
+  case KeyU:
+    return GLFW_KEY_U;
+  case KeyV:
+    return GLFW_KEY_V;
+  case KeyW:
+    return GLFW_KEY_W;
+  case KeyX:
+    return GLFW_KEY_X;
+  case KeyY:
+    return GLFW_KEY_Y;
+  case KeyZ:
+    return GLFW_KEY_Z;
+  }
+}