2015-06-21 17:33:46 +02:00
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/*
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* mixer.c
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* written by Holmes Futrell
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* use however you want
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*/
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2016-03-27 22:26:34 +02:00
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#include "SDL.h"
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#include "common.h"
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2015-06-21 17:33:46 +02:00
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#define NUM_CHANNELS 8 /* max number of sounds we can play at once */
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#define NUM_DRUMS 4 /* number of drums in our set */
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static struct
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{
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SDL_Rect rect; /* where the button is drawn */
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SDL_Color upColor; /* color when button is not active */
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SDL_Color downColor; /* color when button is active */
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int isPressed; /* is the button being pressed ? */
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int touchIndex; /* what mouse (touch) index pressed the button ? */
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} buttons[NUM_DRUMS];
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struct sound
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{
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Uint8 *buffer; /* audio buffer for sound file */
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Uint32 length; /* length of the buffer (in bytes) */
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};
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/* this array holds the audio for the drum noises */
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static struct sound drums[NUM_DRUMS];
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/* function declarations */
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void handleMouseButtonDown(SDL_Event * event);
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void handleMouseButtonUp(SDL_Event * event);
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int playSound(struct sound *);
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2016-09-25 05:23:35 +02:00
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void initializeButtons(SDL_Renderer *);
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2015-06-21 17:33:46 +02:00
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void audioCallback(void *userdata, Uint8 * stream, int len);
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void loadSound(const char *file, struct sound *s);
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struct
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{
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/* channel array holds information about currently playing sounds */
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struct
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{
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Uint8 *position; /* what is the current position in the buffer of this sound ? */
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Uint32 remaining; /* how many bytes remaining before we're done playing the sound ? */
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Uint32 timestamp; /* when did this sound start playing ? */
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} channels[NUM_CHANNELS];
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SDL_AudioSpec outputSpec; /* what audio format are we using for output? */
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int numSoundsPlaying; /* how many sounds are currently playing */
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} mixer;
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/* sets up the buttons (color, position, state) */
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void
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initializeButtons(SDL_Renderer *renderer)
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2015-06-21 17:33:46 +02:00
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{
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int i;
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int spacing = 10; /* gap between drum buttons */
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SDL_Rect buttonRect; /* keeps track of where to position drum */
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SDL_Color upColor = { 86, 86, 140, 255 }; /* color of drum when not pressed */
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SDL_Color downColor = { 191, 191, 221, 255 }; /* color of drum when pressed */
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2016-09-25 05:23:35 +02:00
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int renderW, renderH;
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SDL_RenderGetLogicalSize(renderer, &renderW, &renderH);
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2015-06-21 17:33:46 +02:00
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buttonRect.x = spacing;
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buttonRect.y = spacing;
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2016-09-25 05:23:35 +02:00
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buttonRect.w = renderW - 2 * spacing;
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buttonRect.h = (renderH - (NUM_DRUMS + 1) * spacing) / NUM_DRUMS;
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2015-06-21 17:33:46 +02:00
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/* setup each button */
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for (i = 0; i < NUM_DRUMS; i++) {
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buttons[i].rect = buttonRect;
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buttons[i].isPressed = 0;
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buttons[i].upColor = upColor;
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buttons[i].downColor = downColor;
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buttonRect.y += spacing + buttonRect.h; /* setup y coordinate for next drum */
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}
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}
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/*
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loads a wav file (stored in 'file'), converts it to the mixer's output format,
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and stores the resulting buffer and length in the sound structure
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*/
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void
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loadSound(const char *file, struct sound *s)
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{
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SDL_AudioSpec spec; /* the audio format of the .wav file */
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SDL_AudioCVT cvt; /* used to convert .wav to output format when formats differ */
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int result;
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if (SDL_LoadWAV(file, &spec, &s->buffer, &s->length) == NULL) {
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fatalError("could not load .wav");
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}
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/* build the audio converter */
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result = SDL_BuildAudioCVT(&cvt, spec.format, spec.channels, spec.freq,
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mixer.outputSpec.format,
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mixer.outputSpec.channels,
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mixer.outputSpec.freq);
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if (result == -1) {
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fatalError("could not build audio CVT");
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} else if (result != 0) {
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/*
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this happens when the .wav format differs from the output format.
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we convert the .wav buffer here
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*/
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cvt.buf = (Uint8 *) SDL_malloc(s->length * cvt.len_mult); /* allocate conversion buffer */
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cvt.len = s->length; /* set conversion buffer length */
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SDL_memcpy(cvt.buf, s->buffer, s->length); /* copy sound to conversion buffer */
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if (SDL_ConvertAudio(&cvt) == -1) { /* convert the sound */
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fatalError("could not convert .wav");
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}
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SDL_free(s->buffer); /* free the original (unconverted) buffer */
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s->buffer = cvt.buf; /* point sound buffer to converted buffer */
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s->length = cvt.len_cvt; /* set sound buffer's new length */
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}
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}
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/* called from main event loop */
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void
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handleMouseButtonDown(SDL_Event * event)
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{
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int x, y, mouseIndex, i, drumIndex;
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mouseIndex = 0;
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drumIndex = -1;
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SDL_GetMouseState(&x, &y);
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/* check if we hit any of the drum buttons */
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for (i = 0; i < NUM_DRUMS; i++) {
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if (x >= buttons[i].rect.x
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&& x < buttons[i].rect.x + buttons[i].rect.w
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&& y >= buttons[i].rect.y
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&& y < buttons[i].rect.y + buttons[i].rect.h) {
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drumIndex = i;
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break;
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}
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}
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if (drumIndex != -1) {
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/* if we hit a button */
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buttons[drumIndex].touchIndex = mouseIndex;
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buttons[drumIndex].isPressed = 1;
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playSound(&drums[drumIndex]);
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}
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}
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/* called from main event loop */
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void
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handleMouseButtonUp(SDL_Event * event)
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{
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int i;
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int mouseIndex = 0;
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/* check if this should cause any of the buttons to become unpressed */
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for (i = 0; i < NUM_DRUMS; i++) {
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if (buttons[i].touchIndex == mouseIndex) {
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buttons[i].isPressed = 0;
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}
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}
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}
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/* draws buttons to screen */
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void
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render(SDL_Renderer *renderer)
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{
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int i;
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SDL_SetRenderDrawColor(renderer, 50, 50, 50, 255);
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SDL_RenderClear(renderer); /* draw background (gray) */
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/* draw the drum buttons */
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for (i = 0; i < NUM_DRUMS; i++) {
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SDL_Color color =
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buttons[i].isPressed ? buttons[i].downColor : buttons[i].upColor;
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SDL_SetRenderDrawColor(renderer, color.r, color.g, color.b, color.a);
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SDL_RenderFillRect(renderer, &buttons[i].rect);
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}
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/* update the screen */
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SDL_RenderPresent(renderer);
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}
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/*
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finds a sound channel in the mixer for a sound
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and sets it up to start playing
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*/
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int
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playSound(struct sound *s)
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{
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/*
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find an empty channel to play on.
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if no channel is available, use oldest channel
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*/
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int i;
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int selected_channel = -1;
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int oldest_channel = 0;
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if (mixer.numSoundsPlaying == 0) {
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/* we're playing a sound now, so start audio callback back up */
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SDL_PauseAudio(0);
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}
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/* find a sound channel to play the sound on */
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for (i = 0; i < NUM_CHANNELS; i++) {
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if (mixer.channels[i].position == NULL) {
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/* if no sound on this channel, select it */
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selected_channel = i;
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break;
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}
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/* if this channel's sound is older than the oldest so far, set it to oldest */
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if (mixer.channels[i].timestamp <
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mixer.channels[oldest_channel].timestamp)
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oldest_channel = i;
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}
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/* no empty channels, take the oldest one */
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if (selected_channel == -1)
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selected_channel = oldest_channel;
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else
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mixer.numSoundsPlaying++;
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/* point channel data to wav data */
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mixer.channels[selected_channel].position = s->buffer;
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mixer.channels[selected_channel].remaining = s->length;
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mixer.channels[selected_channel].timestamp = SDL_GetTicks();
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return selected_channel;
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}
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/*
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Called from SDL's audio system. Supplies sound input with data by mixing together all
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currently playing sound effects.
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*/
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void
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audioCallback(void *userdata, Uint8 * stream, int len)
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{
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int i;
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int copy_amt;
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SDL_memset(stream, mixer.outputSpec.silence, len); /* initialize buffer to silence */
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/* for each channel, mix in whatever is playing on that channel */
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for (i = 0; i < NUM_CHANNELS; i++) {
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if (mixer.channels[i].position == NULL) {
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/* if no sound is playing on this channel */
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continue; /* nothing to do for this channel */
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}
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/* copy len bytes to the buffer, unless we have fewer than len bytes remaining */
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copy_amt =
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mixer.channels[i].remaining <
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len ? mixer.channels[i].remaining : len;
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/* mix this sound effect with the output */
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SDL_MixAudioFormat(stream, mixer.channels[i].position,
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2017-09-22 20:15:57 +02:00
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mixer.outputSpec.format, copy_amt, SDL_MIX_MAXVOLUME);
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2015-06-21 17:33:46 +02:00
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/* update buffer position in sound effect and the number of bytes left */
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mixer.channels[i].position += copy_amt;
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mixer.channels[i].remaining -= copy_amt;
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/* did we finish playing the sound effect ? */
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if (mixer.channels[i].remaining == 0) {
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mixer.channels[i].position = NULL; /* indicates no sound playing on channel anymore */
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mixer.numSoundsPlaying--;
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if (mixer.numSoundsPlaying == 0) {
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/* if no sounds left playing, pause audio callback */
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SDL_PauseAudio(1);
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}
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}
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}
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}
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int
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main(int argc, char *argv[])
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{
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int done; /* has user tried to quit ? */
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SDL_Window *window; /* main window */
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SDL_Renderer *renderer;
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SDL_Event event;
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2016-04-01 21:14:49 +02:00
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int i;
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int width;
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int height;
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2015-06-21 17:33:46 +02:00
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if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO) < 0) {
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fatalError("could not initialize SDL");
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}
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2016-09-25 05:23:35 +02:00
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window = SDL_CreateWindow(NULL, 0, 0, 320, 480, SDL_WINDOW_BORDERLESS | SDL_WINDOW_ALLOW_HIGHDPI);
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2015-06-21 17:33:46 +02:00
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renderer = SDL_CreateRenderer(window, 0, 0);
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2016-09-25 05:23:35 +02:00
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SDL_GetWindowSize(window, &width, &height);
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SDL_RenderSetLogicalSize(renderer, width, height);
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2015-06-21 17:33:46 +02:00
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/* initialize the mixer */
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SDL_memset(&mixer, 0, sizeof(mixer));
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/* setup output format */
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mixer.outputSpec.freq = 44100;
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mixer.outputSpec.format = AUDIO_S16LSB;
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mixer.outputSpec.channels = 2;
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mixer.outputSpec.samples = 256;
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mixer.outputSpec.callback = audioCallback;
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mixer.outputSpec.userdata = NULL;
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/* open audio for output */
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if (SDL_OpenAudio(&mixer.outputSpec, NULL) != 0) {
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fatalError("Opening audio failed");
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}
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/* load our drum noises */
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loadSound("ds_kick_big_amb.wav", &drums[3]);
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loadSound("ds_brush_snare.wav", &drums[2]);
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loadSound("ds_loose_skin_mute.wav", &drums[1]);
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loadSound("ds_china.wav", &drums[0]);
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/* setup positions, colors, and state of buttons */
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2016-09-25 05:23:35 +02:00
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initializeButtons(renderer);
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2015-06-21 17:33:46 +02:00
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/* enter main loop */
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done = 0;
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while (!done) {
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while (SDL_PollEvent(&event)) {
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switch (event.type) {
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case SDL_MOUSEBUTTONDOWN:
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handleMouseButtonDown(&event);
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break;
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case SDL_MOUSEBUTTONUP:
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handleMouseButtonUp(&event);
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break;
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case SDL_QUIT:
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done = 1;
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break;
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}
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}
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render(renderer); /* draw buttons */
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2016-09-25 05:23:35 +02:00
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SDL_Delay(1);
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2015-06-21 17:33:46 +02:00
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}
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/* cleanup code, let's free up those sound buffers */
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for (i = 0; i < NUM_DRUMS; i++) {
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SDL_free(drums[i].buffer);
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}
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/* let SDL do its exit code */
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SDL_Quit();
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return 0;
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}
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