在 OSX 上运行 Allegro 5 时找不到主要功能

Question

我正在尝试获取在 OSX 上运行的 Allegro 的最小示例。

我使用 Homebrew 安装了稳定版 Allegro 5.2，as specified in the Allegro wiki。

这是我的代码 (allegro.hpp)：

/*
 * This program uses the Allegro game library to display a blank window.
 *
 * It initializes the display and starts up the main game loop. The
 * game loop only checks for two events: timer (determined by the FPS)
 * and display close (when the user tries to close the window).
 *
 * http://www.damienradtke.org/building-a-mario-clone-with-allegro
 */

#include <stdio.h>
#include <allegro5/allegro.h>

constexpr float FPS = 60.0f;

int main(int argc, char** argv) {
  ALLEGRO_DISPLAY *display = NULL;
  ALLEGRO_EVENT_QUEUE *event_queue = NULL;
  ALLEGRO_TIMER *timer = NULL;

  bool running = true;
  bool redraw = true;

  // Initialize allegro
  if (!al_init()) {
    fprintf(stderr, "Failed to initialize allegro.\n");
    return 1;
  }

  // Initialize the timer
  timer = al_create_timer(1.0f / FPS);
  if (!timer) {
    fprintf(stderr, "Failed to create timer.\n");
    return 1;
  }

  // Create the display
  display = al_create_display(640, 480);
  if (!display) {
    fprintf(stderr, "Failed to create display.\n");
    return 1;
  }

  // Create the event queue
  event_queue = al_create_event_queue();
  if (!event_queue) {
    fprintf(stderr, "Failed to create event queue.");
    return 1;
  }

  // Register event sources
  al_register_event_source(event_queue, al_get_display_event_source(display));
  al_register_event_source(event_queue, al_get_timer_event_source(timer));

  // Display a blank screen
  al_clear_to_color(al_map_rgb(100, 149, 237));
  al_flip_display();

  // Start the timer
  al_start_timer(timer);

  // Game loop
  while (running) {
    ALLEGRO_EVENT event;
    ALLEGRO_TIMEOUT timeout;

    // Initialize timeout
    al_init_timeout(&timeout, 0.06);

    // Fetch the event (if one exists)
    bool get_event = al_wait_for_event_until(event_queue, &event, &timeout);

    // Handle the event
    if (get_event) {
      switch (event.type) {
        case ALLEGRO_EVENT_TIMER:
          redraw = true;
          break;
        case ALLEGRO_EVENT_DISPLAY_CLOSE:
          running = false;
          break;
        default:
          fprintf(stderr, "Unsupported event received: %d\n", event.type);
          break;
      }
    }

    // Check if we need to redraw
    if (redraw && al_is_event_queue_empty(event_queue)) {
      // Redraw
      al_clear_to_color(al_map_rgb(100, 149, 237));
      al_flip_display();
      redraw = false;
    }
  } 

  // Clean up
  al_destroy_display(display);
  al_destroy_event_queue(event_queue);

  return 0;
}

这是我的构建和执行命令：

$ clang++ -I/usr/local/include/ -L/usr/local/lib -lallegro -lallegro_main allegro.hpp -std=c++14 && ./a.out

这是我收到的错误：

dyld: Symbol not found: __al_mangled_main
  Referenced from: /usr/local/opt/allegro/lib/liballegro_main.5.2.dylib
  Expected in: flat namespace
 in /usr/local/opt/allegro/lib/liballegro_main.5.2.dylib
Trace/BPT trap: 5

我已经尝试过其他地方给出的解决方案：

1. 将主函数的签名更改为int main(int argc, char** argv)
2. 链接liballegro_main.dylib

Answer 1

您将其命名为allegro.hpp，尽管它是源文件，而不是头文件。

将其重命名为 <i>something</i>.cpp 或 <i>something</i>.cc。

Answer 2

假设您按照建议将文件重命名为 allegro.cpp，那么这将是构建过程，使用 make

obj =  allegro
CPPFLAGS += -I/usr/local/include
LDFLAGS += -L/usr/local/lib
LDLIBS += -lallegro
LDLIBS += -lallegro_main

.PHONY: all
all : $(obj)

allegro: allegro.cpp

Answer 3

如果你想使用 cmake ...

这应该会让你继续前进

cmake_minimum_required(VERSION 3.17)
project(hi)

set(CMAKE_CXX_STANDARD 14)
# These are where the include files should be
include_directories(/usr/local/include)

# add extra lib directories
link_directories(/usr/local/lib)

add_executable(hi audio2.cpp)

# specify the dependency on an extra library
target_link_libraries(hi allegro allegro_main allegro_acodec allegro_audio)