01 hello window

Tutorial 01 — Hello window

Copyright (c) 2024-2026 Jack Waechter. MIT licensed.

Open a window, clear it, swap. That is the whole AP2 loop.

The loop

#include <AP2/AP2.h>

int main(void) {
  if (!AP_Init(AP_INIT_VIDEO)) {
    return 1;
  }

  if (!AP_CreateWindow("Hello AP2", 1280, 720,
                       AP_WINDOW_RESIZABLE | AP_WINDOW_VSYNC)) {
    AP_Quit();
    return 1;
  }

  while (AP_IsRunning()) {
    AP_PumpEvents();

    if (AP_IsKeyPressed(AP_KEY_ESCAPE)) {
      AP_RequestClose();
    }

    AP_SetDrawColor(0.08f, 0.09f, 0.11f, 1.0f);
    AP_Clear();
    AP_Present();
  }

  AP_DestroyWindow(NULL);
  AP_Quit();
  return 0;
}

What each call does

Call	Role
AP_Init(AP_INIT_VIDEO)	Starts windowing and the graphics device
AP_CreateWindow	One window. Later draw/input calls use it
AP_IsRunning	False after the user hits the close button or AP_RequestClose
AP_PumpEvents	OS events, input, audio tick
AP_Tick	Optional. Caps FPS (AP_SetTargetFPS) and returns dt in seconds
AP_SetDrawColor	RGBA 0–1. AP_Clear uses this color
AP_Clear	Fill the color buffer
AP_Present	Swap (and run post-process if enabled)
AP_DestroyWindow(NULL)	Destroy the active window
AP_Quit	Shut down subsystems

AP_INIT_VIDEO already includes windowing. Add | AP_INIT_AUDIO when you need sound.

Window flags worth knowing

AP_WINDOW_RESIZABLE | AP_WINDOW_HIGH_PIXEL_DENSITY | AP_WINDOW_MSAA | AP_WINDOW_VSYNC

AP_WINDOW_FULLSCREEN is exclusive fullscreen. Size is logical pixels; AP_GetWindowSizeInPixels is the framebuffer size on HiDPI displays.

Caption chrome (decorated windows):

AP_WINDOW_NO_TITLE | AP_WINDOW_NO_MINIMIZE | AP_WINDOW_NO_MAXIMIZE | AP_WINDOW_NO_CLOSE

Or at runtime: AP_SetWindowTitleVisible, AP_SetWindowMinimizeButton, AP_SetWindowMaximizeButton, AP_SetWindowCloseButton. AP_WINDOW_NO_BUTTONS hides all three. Close disabled still lets AP_RequestClose work.

Errors

Failed init or window creation leaves a message in AP_GetErrorMessage(). Log it if you are wiring a real app:

if (!AP_Init(AP_INIT_VIDEO)) {
  AP_ERROR("init: %s", AP_GetErrorMessage());
  return 1;
}

Next

Drawing in 2D