cellular-shader/App.h

#ifndef APP_H
#define APP_H

#include <algorithm>
#include <iterator>
#include <iostream>
#include <fstream>
#include <cmath>
#include <array>
#include <ratio>

#include "stfu/stf.hpp"
#include "pngwriter/pngwriter.h"

#include "shader.h"
#include "fbo.h"

static const std::string filenames[] = {
	"resources/attractor_2011-04-28_10-30-35-2.stf",
	"resources/attractor_2011-04-28_10-05-11-1.stf",
	"resources/attractor_2011-04-29_04-34-41-9.stf",
	"resources/attractor_2011-04-29_15-19-03-9.stf" };

class App {
	int counter;
	unsigned int width, height;

	shader mshader;
	shader clear_shader;
	fbo mfbo;

	static constexpr size_t number_of_lines = 6*50000;
	static constexpr size_t number_of_vertices = 2*number_of_lines;
	std::array<GLfloat, 3*number_of_vertices> lines;
	std::array<GLfloat, 7> parameters;
	std::array<GLfloat, 7> random_parameters;

public:
	App(unsigned int w, unsigned int h) :
		counter(0),
		width(w),
		height(h),
		mshader("resources/myTeaShader.vert", "resources/myTeaShader.frag"),
		clear_shader("resources/myClearShader.vert", "resources/myClearShader.frag"),
		mfbo(width, height) {

		set_points();
		//glEnable(GL_DEPTH_TEST);
		glEnable(GL_BLEND);
		glPointSize(1.0);

		std::string filename = filenames[3];
		set_parameters(filename);
	}

	~App() {
	}

	void resize(int w, int h) {
	}

	void update() {
		++counter;
		iterate();

		if(counter % 500 == 0) {
			set_parameters(filenames[rand() % 4]);
			set_points();
		}
	}

	void draw() {
		clear_shader.begin();
		clear_shader.set_uniform("fade", .5f);
		if( counter < 5 )
			clear_shader.set_uniform("fade", 1.0f);
		fade();

		mshader.begin();
		mshader.set_uniform("steps", counter);

		glRotatef(0.5, std::sin(counter/1337.0), 1.0, 0.0);

		scene();
	}

	void fade() {
		glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
		static const GLfloat quad[] = {
			1.0, 1.0,
			1.0, -1.0,
			-1.0, -1.0,
			-1.0, 1.0 };

		glEnableClientState(GL_VERTEX_ARRAY);
		glVertexPointer(2, GL_FLOAT, 0, &quad[0]);

		// draw a cube
		glDrawArrays(GL_QUADS, 0, 4);

		// deactivate vertex arrays after drawing
		glDisableClientState(GL_VERTEX_ARRAY);
	}

	void scene() {
		glBlendFunc(GL_ONE, GL_ONE);
		glEnableClientState(GL_VERTEX_ARRAY);
		glVertexPointer(3, GL_FLOAT, 0, &lines[0]);

		// draw a cube
		glDrawArrays(GL_POINTS, 0, number_of_vertices);

		// deactivate vertex arrays after drawing
		glDisableClientState(GL_VERTEX_ARRAY);

		//save_screen();
	}

	void iterate() {
		for(size_t i = 0; i < number_of_lines; ++i) {
			GLfloat* vectorNew = &lines[3*2*i];
			GLfloat* vectorOld = &lines[3*2*i+3];
			if(counter % 2) std::swap(vectorNew, vectorOld);

			vectorNew[0] = parameters[0]*(vectorOld[2] + parameters[1]);
			vectorNew[1] = parameters[2]*(vectorOld[0] + parameters[3]);
			vectorNew[2] = parameters[4]*(vectorOld[1] + parameters[5]);

			const double dist = vectorNew[0]*vectorNew[0] + vectorNew[1]*vectorNew[1] + vectorNew[2]*vectorNew[2];

			if(dist > parameters[6]*parameters[6]) {
				const double sqrtDist = std::sqrt(dist);
				const double p = 1.0 - parameters[6] * (static_cast<int>(sqrtDist / parameters[6]) + 1.0) / sqrtDist;
				vectorNew[0] *= p;
				vectorNew[1] *= p;
				vectorNew[2] *= p;
			}
		}

		for(size_t i = 0; i < 7; ++i){
			parameters[i] += random_parameters[i];
		}
	}

	void save_screen(){
		unsigned char data[width*height*6];
		glReadPixels(0, 0, width, height, GL_RGB, GL_UNSIGNED_SHORT, data);

		char filename[256];
		sprintf(filename, "render/shot_%08d.png", counter);

		pngwriter png(width, height, &data[0], filename);
		png.close();
	}

	void set_parameters(std::string filename){
		stfu::node file;
		file.read(filename.c_str());
		for(unsigned int i = 0; i < 7; ++i) {
			stfu::node const attractorParameters = file.getChild("AttractorKernel").getChild("parameters");
			parameters[i] = atof(attractorParameters.getValue(i).c_str());
			random_parameters[i] = (rand() / (double)RAND_MAX - 0.5) * counter / 500000.0;
		}
	}

	void set_points(){
		std::generate(lines.begin(), lines.end(), []() { return 2.0 * rand() / (double)RAND_MAX - 1.0; });
	}
};

#endif // APP_H