gunslinger/examples/simple_audio/source/main.c

/*================================================================
	* Copyright: 2020 John Jackson
	* simple_audio

	Simple audio example. Demonstrates how to load raw audio data
		from disk (.mp3), construct an internal resource and then 
		use audio instances to play audio at runtime.

	Demonstrates how to play, pause, restart, stop, control volume
	of audio, as well as get runtime data for the playing instance.

	Press `esc` to exit the application.
=================================================================*/

#include <gs.h>

// Forward Decls.
gs_result app_init();		// Use to init your application
gs_result app_update();		// Use to update your application

// Resource handles for internal audio data. Since audio must run on a separate thread, this is necessary.
gs_global gs_resource(gs_audio_source_t) 		g_src = {0};
gs_global gs_handle_audio_instance 				g_inst = {0};

int main(int argc, char** argv)
{
	// This is our app description. It gives internal hints to our engine for various things like 
	// window size, title, as well as update, init, and shutdown functions to be run. 
	gs_application_desc_t app = {0};
	app.window_title 		= "Simple Audio";
	app.window_width 		= 800;
	app.window_height 		= 600;
	app.init 				= &app_init;
	app.update 				= &app_update;

	// Construct internal instance of our engine
	gs_result res = gs_engine_construct(app)->run();

	// Check result of engine after exiting loop
	if (res != gs_result_success) 
	{
		gs_println("Error: Engine did not successfully finish running.");
		return -1;
	}

	gs_println("Gunslinger exited successfully.");

	return 0;	
}

gs_result app_init()
{
	// Cache apis
	gs_platform_i* platform = gs_engine_subsystem(platform);
	gs_audio_i* audio 		= gs_engine_subsystem(audio);

	// Constuct audio resource to play
	g_src = audio->load_audio_source_from_file(platform->file_exists("./assets/cold_morning_tx.mp3") ? 
		"./assets/cold_morning_tx.mp3" : "./../assets/cold_morning_tx.mp3");

	// Construct instance source and play on loop. Forever.
	// Fill out instance data to pass into audio subsystem
	gs_audio_instance_data_t inst = gs_audio_instance_data_new(g_src);
	inst.volume = 0.8f;						// Range from [0.f, 1.f]
	inst.loop = true;						// Tell whether or not audio should loop 
	inst.persistent = true;					// Whether or not instance should stick in memory after completing, if not then will be cleared from memory
	g_inst = audio->construct_instance(inst);
	audio->play(g_inst);

	return gs_result_success;
}

gs_result app_update()
{
	// Cache necessary APIs
	gs_platform_i* platform = gs_engine_instance()->ctx.platform;	
	gs_audio_i* audio = gs_engine_instance()->ctx.audio;

	if (platform->key_pressed(gs_keycode_esc)) 
	{
		return gs_result_success;
	}

	if (platform->key_pressed(gs_keycode_p))
	{
		if (audio->is_playing(g_inst)) 
		{
			audio->pause(g_inst);
		} 
		else 
		{
			audio->play(g_inst);
		}
	}

	// Restart instance
	if (platform->key_pressed(gs_keycode_r))
	{
		audio->restart(g_inst);
	}

	// Stop audio (sets position back to beginning)
	if (platform->key_pressed(gs_keycode_s))
	{
		audio->stop(g_inst);
	}

	// Volume up
	if (platform->key_pressed(gs_keycode_up))
	{
		f32 cur_vol = audio->get_volume(g_inst);
		audio->set_volume(g_inst, cur_vol + 0.1f);
	}

	// Volume down
	if (platform->key_pressed(gs_keycode_down))
	{
		f32 cur_vol = audio->get_volume(g_inst);
		audio->set_volume(g_inst, cur_vol - 0.1f);
	}

	// Can grab current runtime instance data as well
	gs_audio_instance_data_t id = audio->get_instance_data(g_inst);

	s32 sample_count = audio->get_sample_count(id.src);
	s32 sample_rate = audio->get_sample_rate(id.src);
	s32 num_channels = audio->get_num_channels(id.src);

	gs_timed_action(10, 
	{
		s32 min, sec;
		char buf[256] = gs_default_val();

		// Runtime of source
		audio->get_runtime(g_src, &min, &sec);
		gs_snprintf(buf, 256, sec < 10 ? "%d:0%d" : "%d:%d", min, sec);
		gs_println("Runtime: %s", buf);

		// Get current play position
		audio->convert_to_runtime(sample_count, sample_rate, 
			num_channels, id.sample_position, &min, &sec);

		gs_snprintf(buf, 256, sec < 10 ? "%d:0%d" : "%d:%d", min, sec);
		gs_println("Play Time: %s", buf);
	});

	return gs_result_in_progress;
}