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#include <SDL2/SDL.h>
#define _USE_MATH_DEFINES
#include <cmath>
#include <iostream>
const float AMPLITUDE = 0.2f;
const float sequence[8] = { 130.81f, 220.f, 130.81f, 440.f, 330.f, 440.f, 130.81f, 261.63f };
struct CallbackInfo {
int samplesDone;
int samplesPerStep;
int currentStep;
int sampleRate;
};
void AudioCallback(void *userData, Uint8 *rawBuffer, int bytes)
{
float *buffer = (float*)rawBuffer;
int length = bytes / sizeof(float);
CallbackInfo *info = (CallbackInfo*)userData;
for (int i = 0; i < length; i++, info->samplesDone++) {
float freq = sequence[info->currentStep];
float time = (float)info->samplesDone / (float)info->sampleRate;
if (info->samplesDone >= info->samplesPerStep) {
info->samplesDone = 0;
info->currentStep = (info->currentStep + 1) % 8;
}
buffer[i] = (sinf(2.0f * M_PI * freq * time)) * AMPLITUDE;
}
}
void DrawInterface(SDL_Renderer* renderer, int currentStep)
{
SDL_Rect rect = {
(640 - 8 * (32 + 8)) / 2,
(320 - 32) / 2,
32,
32
};
for (int i = 0; i < 8; i++) {
SDL_SetRenderDrawColor(renderer, 128, i * (255 / 8), 255, 255);
if (i == currentStep) {
SDL_RenderFillRect(renderer, &rect);
} else {
SDL_RenderDrawRect(renderer, &rect);
}
rect.x += rect.w + 8;
}
}
int main(int argc, char** argv)
{
if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO) < 0) {
std::cerr << "Failed to initalize SDL! " << SDL_GetError() << std::endl;
return 1;
}
SDL_Window* window = SDL_CreateWindow("fmseq", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, 640, 320, SDL_WINDOW_SHOWN);
SDL_Renderer* renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED);
SDL_Event event;
CallbackInfo info;
SDL_AudioSpec desiredSpec;
desiredSpec.freq = 44100;
desiredSpec.format = AUDIO_F32SYS;
desiredSpec.channels = 1;
desiredSpec.samples = 2048;
desiredSpec.callback = AudioCallback;
desiredSpec.userdata = &info;
SDL_AudioSpec obtainedSpec;
if (SDL_OpenAudio(&desiredSpec, &obtainedSpec) < 0) {
std::cerr << "Failed to initalize audio! " << SDL_GetError() << std::endl;
return 1;
}
if (desiredSpec.format != obtainedSpec.format)
std::cerr << "Different format: " << obtainedSpec.format << std::endl;
info.samplesDone = 0;
info.samplesPerStep = obtainedSpec.freq * 0.4f;
info.currentStep = 0;
info.sampleRate = obtainedSpec.freq;
SDL_PauseAudio(0);
bool running = true;
while (running) {
while (SDL_PollEvent(&event)) {
switch (event.type) {
case SDL_QUIT:
running = false;
break;
}
}
SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
SDL_RenderClear(renderer);
DrawInterface(renderer, info.currentStep);
SDL_RenderPresent(renderer);
SDL_UpdateWindowSurface(window);
SDL_Delay(10);
}
SDL_PauseAudio(1);
SDL_CloseAudio();
SDL_DestroyWindow(window);
SDL_Quit();
return 0;
}
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