OF Metaballs

ofApp.cpp

#include "ofApp.h"

#include <glm/gtx/fast_square_root.hpp>

void ofApp::setup()
{
	for (int i = 0; i < 10; i++) 
	{
		blobs.push_back(Blob(ofRandomWidth(), ofRandomHeight()));
	}

	canvas.allocate(ofGetWidth(), ofGetHeight(), OF_IMAGE_GRAYSCALE);
}

void ofApp::update()
{
	for (Blob& b : blobs) 
	{
		b.update();
	}

	auto pixels = canvas.getPixels().getData();
	for (int x = 0; x < ofGetWidth(); x++) 
	{
		for (int y = 0; y < ofGetHeight(); y++) 
		{
			int index = x + y * ofGetWidth();
			float sum = 0;
			for (Blob& b : blobs) 
			{
				//float d = glm::distance(glm::vec2(x, y), b.pos);
				//float d = glm::fastDistance(glm::vec2(x, y), b.pos);
				glm::vec2 toPos = b.pos - glm::vec2(x, y);
				float d = sqrtf(toPos.x * toPos.x + toPos.y * toPos.y);

				sum += 10 * b.r / d;
			}
			pixels[index] = min(255.0f, sum);
		}
	}
	canvas.update();
}

void ofApp::draw()
{
	canvas.draw(0, 0);
	ofDrawBitmapStringHighlight(ofToString(ofGetFrameRate(), 2), 10, 20);
}

ofApp.h

#pragma once

#include "ofMain.h"

class Blob 
{
public:
	glm::vec2 pos;
	float r;
	glm::vec2 vel;

	Blob(float x, float y) 
	{
		pos = glm::vec2(x, y);
		vel = glm::vec2(ofRandomf(), ofRandomf());
		vel *= ofRandom(2, 5);
		r = ofRandom(120, 400);
	}

	void update() 
	{
		pos += vel;
		if (pos.x > ofGetWidth() || pos.x < 0) 
		{
			vel.x *= -1;
		}
		if (pos.y > ofGetHeight() || pos.y < 0) 
		{
			vel.y *= -1;
		}
	}
};

class ofApp : public ofBaseApp 
{
public:
	void setup();
	void update();
	void draw();

	std::vector<Blob> blobs;
	ofImage canvas;
};