Simulation of synthesizer built from 256 perfect logic gates with 32 fixed inputs.

main.cpp

#include "ofMain.h"

// what happens when we can look back in time? i.e., add delays to io?
//  this can be modeled with one pass-through-gate or two not-gates.
//  or with a single and-gate with both inputs connect to the same output.
// what happens when the the circuit can control its own topology?
//  this can be modeled with a very large circuit that switches between sub-circuits
// what happens when we use gates with more than two inputs?
//  this can be modeled with a sub-circuit
// what happens when gates have floating point values with schmitt triggers?
//  not sure that this can be modeled.

// how does distance from the inputs affect the randomness of the behavior?

// this can be evaluated much faster for large circuits on the GPU.

typedef bool (*Operation) (bool, bool);

bool bool_or(bool a, bool b) {return a || b;}
bool bool_nor(bool a, bool b) {return !(a || b);}
bool bool_and(bool a, bool b) {return a && b;}
bool bool_nand(bool a, bool b) {return !(a && b);}
bool bool_xor(bool a, bool b) {return a ^ b;}
bool bool_xnor(bool a, bool b) {return !(a ^ b);}

class HasOutput {
private:
	bool output, bufferedOutput;
protected:
	void bufferOutput(bool output) {
		this->bufferedOutput = output;
	}
	void updateOutput() {
		this->output = this->bufferedOutput;
	}
public:
	HasOutput()
	:output(false)
	,bufferedOutput(false) {
	}
	bool getOutput() const {
		return output;
	}
};

class Input : public HasOutput {
public:
	void setOutput(bool output) {
		bufferOutput(output);
		updateOutput();
	}
};

class Gate : public HasOutput {
protected:
	HasOutput *input0, *input1;
	Operation operation;
public:
	Gate()
	:input0(NULL)
	,input1(NULL)
	,operation(NULL) {
	}
	void setOperation(Operation operation) {
		this->operation = operation;
	}
	void setInput0(HasOutput& input) {
		input0 = &input;
	}
	void setInput1(HasOutput& input) {
		input1 = &input;
	}
	void evaluate() {
		bufferOutput((*operation) (input0->getOutput(), input1->getOutput()));
	}
	void update() {
		updateOutput();
	}
};

template <class T>
T& randomElement(vector<T>& elements) {
	return elements[ofRandom(0, elements.size())];
}

int n = 256;
int downsample = 1;
float volume = .1;
vector<Input> inputs(32);
vector<Gate> gates(n);
vector<Operation> operations;

class ofApp : public ofBaseApp {
public:
	bool needToReset = false;
	
	ofImage raw, img;
	
	void setup() {
		raw.allocate(gates.size(), n, OF_IMAGE_GRAYSCALE);
		raw.setColor(ofColor::black);
		img.allocate(gates.size(), n, OF_IMAGE_GRAYSCALE);
		img.setColor(ofColor::black);
		operations.push_back(&bool_or);
		operations.push_back(&bool_nor);
		operations.push_back(&bool_and);
		operations.push_back(&bool_nand);
		operations.push_back(&bool_xor);
		operations.push_back(&bool_xnor);
		reset();
		ofSoundStreamSetup(2, 0, 44100, n, 4);
	}
	void reset() {
		// randomly connect all the gates
		for(int i = 0; i < n; i++) {
			gates[i] = Gate();
			gates[i].setOperation(randomElement(operations));
			gates[i].setInput0(randomElement(gates));
			gates[i].setInput1(randomElement(gates));
		}
		// connect and set all the inputs
		for(int i = 0; i < inputs.size(); i++) {
			inputs[i].setOutput(ofRandom(1) > .5);
			randomElement(gates).setInput0(inputs[i]);
		}
	}
	void update() {
		img.update();
		raw.update();
	}
	void draw() {
		raw.draw(0, 0);
		img.draw(n, 0);
	}
	void keyPressed(int key) {
		if(key == ' ') {
			needToReset = true;
		}
	}
	void audioOut(float* input, int bufferSize, int nChannels) {
		if(needToReset) {
			reset();
			needToReset = false;
		}
		int sqn = sqrt(n);
		int mx = ofClamp(mouseX, 0, n - 1) / sqn, my = ofClamp(mouseY, 0, n - 1) / sqn;
		int request = my * sqn + mx;
		int totalIterations = bufferSize / downsample;
		int duplicates = nChannels * downsample;
		for(int i = 0; i < totalIterations; i++) {
			// evaluate all gates
			for(int j = 0; j < n; j++) {
				gates[j].evaluate();
			}
			// update all gates
			for(int j = 0; j < n; j++) {
				gates[j].update();
			}
			// save state to image
			for(int j = 0; j < n; j++) {
				int xs = i % sqn, ys = i / sqn;
				int xb = j % sqn, yb = j / sqn;
				int x = xb * sqn + xs, y = yb * sqn + ys;
				raw.setColor(x, y, gates[j].getOutput() ? ofColor::white : ofColor::black);
				img.setColor(i, j, gates[j].getOutput() ? ofColor::white : ofColor::black);
			}
			float result = gates[request].getOutput() ? +volume : -volume;
			for(int j = 0; j < duplicates; j++) {
				input[i * duplicates + j] = result;
			}
		}
	}
};

int main() {
	ofSetupOpenGL(2 * n, n, OF_WINDOW);
	ofRunApp(new ofApp());
}