code thingie, use to replace fluidsim2.cpp

#include "base.h"

/*#include <fstream>
#include <SFML\Graphics.hpp>
#include <string>
#include <vector>
#include <math.h>

const double e=2.71828183;*/

const int w=64,h=48; //width and height of the simulation in cells
const int px_per_cell_w=4,px_per_cell_h=4; //width and height of a single cell in pixels
const float change_weight=2.0; //rate of change towards average value of neighbours per step, 1=100% change 0=no change
float grid[w][h]={0};
float grid_new[w][h]={0};
float power=0.005;
sf::Vector2i mouse;

float positive(float x)
{
	if(x<0) return -x;
	return x;
}
float sign(float x) //for use in "to_channel" function
{
	if(x>0) return 1;
	if(x<0) return -1;
	return 0;
}

float cast_0to1sharp(float x)
{
	return 1.0-1.0/(1.0+sqrt(abs(x))); //useful for mapping a logarithmically large but positive (including 0) range of values to a value from 0 to 1
}
float cast_0to1soft(float x) //useful for mapping a logarithmically large but positive (including 0) range of values to a value from 0 to 1
{
	return 1.0-1.0/(1.0+abs(x));
}
float to_channel(float channel) //for use of pixel display
{
	return 128.0*sign(channel)*cast_0to1soft(channel)+128.0; //useful for mapping a logarithmically large (but not necessarily positive) range of values from 0 to 1
}

float get(int x,int y)
{
	int cx=x,cy=y;
	if(x<0) cx=w-1;
	if(y<0) cy=h-1;
	if(x>=w) cx=0;
	if(y>=h) cy=0;
	return grid[cx][cy];
}

int main()
{
	sf::Clock clock;
	sf::ContextSettings set;
	set.antialiasingLevel=8;
	sf::RenderWindow window(sf::VideoMode(w*px_per_cell_w,h*px_per_cell_h),"fluid sim");
	while(window.isOpen())
	{
		clock.restart();
		sf::Event event;
		while (window.pollEvent(event)) {if (event.type == sf::Event::Closed) window.close();}
		window.clear(sf::Color::Black);

		//[do physics step and render]

		//user interaction
		mouse.x=sf::Mouse::getPosition(window).x-1000;//I only add 1000 so that I can evade this weird strangely x-axis-specific glitch
		mouse.y=sf::Mouse::getPosition(window).y;
		float temp=grid[(mouse.x/px_per_cell_w)%w][(mouse.y/px_per_cell_h)%h];
		if(mouse.x>=0 && mouse.x<w*px_per_cell_w && mouse.y>=0 && mouse.y<h*px_per_cell_h)
		{
			if(sf::Mouse::isButtonPressed(sf::Mouse::Button::Left))
			{
				grid[(mouse.x/px_per_cell_w)%w][(mouse.y/px_per_cell_h)%h]+=32.0;//+abs(temp)*power;
			}
			if(sf::Mouse::isButtonPressed(sf::Mouse::Button::Right))
			{
				grid[(mouse.x/px_per_cell_w)%w][(mouse.y/px_per_cell_h)%h]-=32.0;//+abs(temp)*power;
			}
		}

		//simulation and rendering
		for(int cy=0;cy<h;cy++)
		{
			for(int cx=0;cx<w;cx++)
			{
				//for convenience of reference
				float curcell=grid[cx][cy];
				float newcell=grid_new[cx][cy];

				//what is our neighbourhood? (I've organised it so that it is visually obvious what neighbour each term corresponds to)
				float neighbour[8]=
				{get(cx-1,cy-1),get(cx,cy-1),get(cx+1,cy-1),
				 get(cx-1,cy),				 get(cx+1,cy),
				 get(cx-1,cy+1),get(cx,cy+1),get(cx+1,cy+1)};

				//calculate the average
				float average=0;
				for(int i=0;i<8;i++)
				{
					average+=neighbour[i]/8.0;
				}

				newcell+=(average-curcell)/change_weight; //find the difference between the average and the current value, and divide by change_weight, then change by that
				float difference=curcell-newcell;
				grid_new[cx][cy]=newcell;
				sf::RectangleShape square(sf::Vector2f(px_per_cell_w,px_per_cell_h));

				float b=to_channel(difference*10.0); //float b=255*(1.0-1.0/(1+curcell));
				float g=255.0/(1.0+pow(e,-curcell)); //float g=255*(1.0-1.0/(1+sqrt(curcell*2.0)));
				float r=255.0/(1.0+pow(e,curcell)); //float r=255*(1.0-1.0/(1+sqrt(sqrt(curcell*4.0))));
				square.setFillColor(sf::Color(r,g,b));
				square.setPosition(sf::Vector2f(cx*px_per_cell_w,cy*px_per_cell_h));
				window.draw(square);
			}
		}
		//copy new array of grid cells to old one
		for(int cy=0;cy<h;cy++)
		{
			for(int cx=0;cx<w;cx++)
			{
				grid[cx][cy]=grid_new[cx][cy];
			}
		}
		//window.draw(pwrdisp);
		window.display();
		//end step
		//attempting to sleep a negative amount of time will probably either crash it, cause the universe to stop existing or make a time travel machine...
		sf::Time sleep_time=sf::seconds(1.0/60.0)-clock.getElapsedTime(),no_time=sf::seconds(0.0);
		if(sleep_time>no_time) sf::sleep(sleep_time);
	}
	return 0;
}