Mikemon/libs/SDL3_mixer/test/testspatialization.c

/*
  SDL_mixer:  An audio mixer library based on the SDL library
  Copyright (C) 1997-2026 Sam Lantinga <slouken@libsdl.org>

  This software is provided 'as-is', without any express or implied
  warranty.  In no event will the authors be held liable for any damages
  arising from the use of this software.

  Permission is granted to anyone to use this software for any purpose,
  including commercial applications, and to alter it and redistribute it
  freely, subject to the following restrictions:

  1. The origin of this software must not be misrepresented; you must not
     claim that you wrote the original software. If you use this software
     in a product, an acknowledgment in the product documentation would be
     appreciated but is not required.
  2. Altered source versions must be plainly marked as such, and must not be
     misrepresented as being the original software.
  3. This notice may not be removed or altered from any source distribution.
*/

#define SDL_MAIN_USE_CALLBACKS 1  /* use the callbacks instead of main() */
#include <SDL3/SDL.h>
#include <SDL3/SDL_main.h>
#include "SDL3_mixer/SDL_mixer.h"

static SDL_Window *window = NULL;
static SDL_Renderer *renderer = NULL;
static MIX_Mixer *mixer = NULL;
static MIX_Track *track = NULL;
static bool autopilot = true;
static bool mouse_down = false;
static float mouse_x, mouse_y;

SDL_AppResult SDL_AppInit(void **appstate, int argc, char *argv[])
{
    SDL_SetAppMetadata("Test SDL_mixer spatialization", "1.0", "org.libsdl.testmixerspatialization");

    if (argc != 2) {
        SDL_Log("USAGE: %s <file_to_play>", argv[0]);
        return SDL_APP_FAILURE;
    } else if (!SDL_Init(SDL_INIT_VIDEO)) {   // it's safe to SDL_INIT_AUDIO, but MIX_Init will do it for us.
        SDL_Log("Couldn't initialize SDL: %s", SDL_GetError());
        return SDL_APP_FAILURE;
    } else if (!MIX_Init()) {
        SDL_Log("Couldn't initialize SDL_mixer: %s", SDL_GetError());
        return SDL_APP_FAILURE;
    } else if (!SDL_CreateWindowAndRenderer("testmixer", 640, 480, 0, &window, &renderer)) {
        SDL_Log("Couldn't create window/renderer: %s", SDL_GetError());
        return SDL_APP_FAILURE;
    } else if ((mixer = MIX_CreateMixerDevice(SDL_AUDIO_DEVICE_DEFAULT_PLAYBACK, NULL)) == NULL) {
        SDL_Log("Couldn't create mixer: %s", SDL_GetError());
        return SDL_APP_FAILURE;
    }

    const char *audiofname = argv[1];
    MIX_Audio *audio = MIX_LoadAudio(mixer, audiofname, false);
    if (!audio) {
        SDL_Log("Failed to load '%s': %s", audiofname, SDL_GetError());
        return SDL_APP_FAILURE;
    }

    track = MIX_CreateTrack(mixer);
    MIX_SetTrackAudio(track, audio);

    SDL_PropertiesID options = SDL_CreateProperties();
    SDL_SetNumberProperty(options, MIX_PROP_PLAY_LOOPS_NUMBER, -1);
    MIX_PlayTrack(track, options);
    SDL_DestroyProperties(options);

    return SDL_APP_CONTINUE;
}

SDL_AppResult SDL_AppEvent(void *appstate, SDL_Event *event)
{
    if (event->type == SDL_EVENT_QUIT) {
        return SDL_APP_SUCCESS;
    } else if ((event->type == SDL_EVENT_KEY_DOWN) && (event->key.key == SDLK_ESCAPE)) {
        return SDL_APP_SUCCESS;
    } else if ((event->type == SDL_EVENT_KEY_DOWN) && (event->key.key == SDLK_A)) {
        autopilot = true;
    } else if ((event->type == SDL_EVENT_MOUSE_BUTTON_DOWN) && (event->button.button == 1)) {
        mouse_down = true;
    } else if ((event->type == SDL_EVENT_MOUSE_BUTTON_UP) && (event->button.button == 1)) {
        autopilot = false;
        mouse_down = false;
    } else if (event->type == SDL_EVENT_MOUSE_MOTION) {
        if (mouse_down) {
            autopilot = false;
            mouse_x = event->motion.x;
            mouse_y = event->motion.y;
        }
    }
    return SDL_APP_CONTINUE;
}

SDL_AppResult SDL_AppIterate(void *appstate)
{
    const Uint64 period = 5000;
    const float moment = ((float) (SDL_GetTicks() % period)) / ((float) period);  // moment in the time period, from 0.0f to 1.0f
    const float angle = moment * 2.0f * SDL_PI_F;  // angle on the circle for this moment, in radians.
    static const SDL_FPoint center = { 640.0f / 2.0f, 480.0f / 2.0f };
    const float radius = 200.0f;  // size of half the circle (radius, not diameter).
    const float boxsize = 30.0f;
    SDL_FPoint sourcept;
    MIX_Point3D position;

    position.y = 0.0f;  // always horizontal.

    if (autopilot) {  // run in a horizontal circle around the listener (circling on X and Z coordinates).
        position.x = SDL_cosf(angle);
        position.z = SDL_sinf(angle);
        sourcept.x = center.x + (position.x * radius);
        sourcept.y = center.y + (position.z * radius);
    } else {
        position.x = (((mouse_x / 640.0f) * 2.0f) - 1.0f);  // scale to -1.0f to 1.0f
        position.z = (((mouse_y / 480.0f) * 2.0f) - 1.0f);
        sourcept.x = mouse_x - (boxsize / 2.0f);
        sourcept.y = mouse_y - (boxsize / 2.0f);
    }

    #if 0
    const float scale = 3.0f;
    position.x *= scale;  // make distance attenuation noticable.
    position.z *= scale;
    MIX_SetTrack3DPosition(track, &position);
    #else
    const float right = (position.x + 1.0f) / 2.0f;  // move to 0.0f - 1.0f.
    const MIX_StereoGains gains = { 1.0f - right, right };
    MIX_SetTrackStereo(track, &gains);
    #endif

    SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
    SDL_RenderClear(renderer);

    const SDL_FRect source_rect = { sourcept.x, sourcept.y, boxsize, boxsize };
    SDL_SetRenderDrawColor(renderer, 0, 0, 255, 255);
    SDL_RenderFillRect(renderer, &source_rect);
    SDL_SetRenderDrawColor(renderer, 255, 255, 255, 255);
    SDL_RenderDebugText(renderer, source_rect.x + ((boxsize - 48.0f) / 2.0f), source_rect.y + boxsize, "SOURCE");

    const SDL_FRect listener_rect = { center.x, center.y, boxsize, boxsize };
    SDL_SetRenderDrawColor(renderer, 0, 255, 0, 255);
    SDL_RenderFillRect(renderer, &listener_rect);
    SDL_SetRenderDrawColor(renderer, 255, 255, 255, 255);
    SDL_RenderDebugText(renderer, listener_rect.x + ((boxsize - 64.0f) / 2.0f), listener_rect.y + boxsize, "LISTENER");

    SDL_RenderPresent(renderer);

    return SDL_APP_CONTINUE;
}

void SDL_AppQuit(void *appstate, SDL_AppResult result)
{
    // SDL will clean up the window/renderer for us.
    // SDL_mixer will clean up the tracks and audio.
    MIX_Quit();
}