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#include <SDL2/SDL.h>
#define _USE_MATH_DEFINES
#include <cmath>
#include <iostream>
#include <vector>
const float AMPLITUDE = 0.2f;
float sequence[8] = { 130.81f, 220.f, 130.81f, 440.f, 330.f, 440.f, 130.81f, 261.63f };
float modSequence[8] = { 0, 0, 0, 0, 0, 0, 0, 0 };
float mulSequence[8] = { 1, 1, 1, 1, 1, 1, 1, 1 };
class Knob {
public:
Knob(int x, int y, float *valuePtr, float scaling = 1.f)
: m_x(x), m_y(y), value(valuePtr), valueScaling(scaling) {}
void Draw(SDL_Renderer*);
bool InBounds(int x, int y);
float *value;
float valueScaling;
private:
int m_x, m_y;
};
std::vector<Knob> knobs;
class Window {
public:
Window();
private:
bool m_isRunning{ false };
};
void Knob::Draw(SDL_Renderer *renderer)
{
constexpr int Radius = 25;
SDL_Rect rect = { m_x, m_y, Radius, Radius };
SDL_RenderDrawRect(renderer, &rect);
SDL_RenderDrawLine(renderer, m_x, m_y + (*value * valueScaling), m_x + Radius, m_y + (*value * valueScaling));
}
bool Knob::InBounds(int x, int y)
{
constexpr int Radius = 25;
SDL_Rect rect = { m_x, m_y, Radius, Radius };
SDL_Point point = { x, y };
return SDL_PointInRect(&point, &rect);
}
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 time = (float)info->samplesDone / (float)info->sampleRate;
float modWave = sinf(2.0f * M_PI * modSequence[info->currentStep] * time);
float freq = sequence[info->currentStep] + modWave * mulSequence[info->currentStep] ;
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;
}
for (Knob& knob : knobs) {
knob.Draw(renderer);
}
}
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);
knobs.emplace_back(10, 120, sequence, 0.1f);
knobs.emplace_back(40, 120, sequence + 1, 0.1f);
knobs.emplace_back(70, 120, sequence + 2, 0.1f);
knobs.emplace_back(110, 120, sequence + 3, 0.1f);
knobs.emplace_back(140, 120, sequence + 4, 0.1f);
knobs.emplace_back(170, 120, sequence + 5, 0.1f);
knobs.emplace_back(210, 120, sequence + 6, 0.1f);
knobs.emplace_back(240, 120, sequence + 7, 0.1f);
knobs.emplace_back(10, 180, modSequence);
knobs.emplace_back(40, 180, modSequence + 1);
knobs.emplace_back(70, 180, modSequence + 2);
knobs.emplace_back(110, 180, modSequence + 3);
knobs.emplace_back(140, 180, modSequence + 4);
knobs.emplace_back(170, 180, modSequence + 5);
knobs.emplace_back(210, 180, modSequence + 6);
knobs.emplace_back(240, 180, modSequence + 7);
knobs.emplace_back(10, 220, mulSequence, 3.0f);
knobs.emplace_back(40, 220, mulSequence + 1, 3.0f);
knobs.emplace_back(70, 220, mulSequence + 2, 3.0f);
knobs.emplace_back(110, 220, mulSequence + 3, 3.0f);
knobs.emplace_back(140, 220, mulSequence + 4, 3.0f);
knobs.emplace_back(170, 220, mulSequence + 5, 3.0f);
knobs.emplace_back(210, 220, mulSequence + 6, 3.0f);
knobs.emplace_back(240, 220, mulSequence + 7, 3.0f);
bool running = true;
Knob* mouseKnob = nullptr;
int yStart = 0;
while (running) {
while (SDL_PollEvent(&event)) {
switch (event.type) {
case SDL_QUIT:
running = false;
break;
case SDL_MOUSEBUTTONDOWN:
for (Knob& knob : knobs) {
if (knob.InBounds(event.button.x, event.button.y)) {
mouseKnob = &knob;
yStart = event.button.y;
break;
}
}
break;
case SDL_MOUSEMOTION:
if (mouseKnob) {
*mouseKnob->value -= (yStart - event.button.y) / mouseKnob->valueScaling;
yStart = event.button.y;
if (*mouseKnob->value < 0) *mouseKnob->value = 0;
}
break;
case SDL_MOUSEBUTTONUP:
mouseKnob = nullptr;
yStart = 0;
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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