Computercraft fish

fish.lua

local fishStringL = "<'((>-<";
local fishStringR = ">-<))'>";
local fishLength = 7;

local foodDist = 5;

-- A float between -1 and 1
local randFloat = function()
  return math.random(-100, 100) / 100;
end


local renderFish = function(t, fish)
--  t.write(fish.x .. ", " .. fish.y)
  t.setCursorPos(fish.x, fish.y);
  local fs;
  if fish.xv >= 0 then
    fs = fishStringR;
  else
    fs = fishStringL;
  end
  
  t.write(fs);
end

local renderFood = function(t, food)
  t.setCursorPos(food.x, food.y);
  t.write("O")
end

local clampFish = function(fish, w, h)
  if fish.x > (w - (fishLength - 1)) then
    fish.x = w - (fishLength - 1)
  end
  
  if fish.x < 1 then
    fish.x = 1
  end
  
  if fish.y > h then
    fish.y = h
  end
  
  if fish.y < 1 then
    fish.y = 1
  end
end

local maxTime = 10;

local maxVFactor = 0.05;

local directFish = function(fish, w, h, time)
  if time - fish.epoch > maxTime then
    fish.xv = randFloat() * maxVFactor * w;
    fish.yv = randFloat() * maxVFactor * h;
    fish.epoch = time;
  end
end

local moveThing = function(fish, time)
  local dt = time - fish.ltime;
  fish.x = fish.x + fish.xv * dt;
  fish.y = fish.y + fish.yv * dt;
  fish.ltime = time;
end

local initFish = function(w, h, e)
  return {
    x = math.random(1, w),
    y = math.random(1, h),
    xv = 0,
    yv = 0,
    epoch = e,
    ltime = e
  }
end

local initFood = function(w, h, e)
  return {
    gone = false,
    ltime = e,
    x = math.random(1, w),
    y = 0,
    xv = 0,
    yv = maxVFactor * h -- That's some fast food..
  }
end

local simFish = function(trm, fish, w, h, time)
  directFish(fish, w, h, time);
  moveThing(fish, time);
  clampFish(fish, w, h);
  renderFish(trm,fish);
end

local simFood = function(trm, food, w, h, time)
  moveThing(food, time);
  renderFood(trm, food);
end

local dist = function(a, b)
  local dx = b.x - a.x;
  local dy = b.y - a.y;
  return (dx * dx) + (dy * dy);
end

local collide = function(fish, food)
  local dx = 0;
  if fish.xv >= 0 then
    dx = fishLength;
  end
  
  return dist({x=fish.x + dx, y = fish.y}, food) <= 5
end



local simulate = function(config)
	local trm = config.Term;
	local tw = config.Width;
	local th = config.Height;
	local nfish = config.NFish;
	
	local fishies = {};

	local nfood = 0;
	local noms = {};
	
	-- Initialize fishies
	for i = 0, nfish-1,1 do
	  fishies[i] = initFish(tw, th, 0)
	end

	local fishTime = 0;
	
	while true do
	  trm.clear();

	  for i = 0, nfish-1, 1 do
	    simFish(trm, fishies[i], tw, th, fishTime);
	  end
	  
	  for i = 0, nfood-1, 1 do
	    simFood(trm, noms[i], tw, th, fishTime);
	  end
	  
	  -- Check for food collisions
	  for i = 0, nfish-1, 1 do
	    for j = 0, nfood-1, 1 do
	      if collide(fishies[i], noms[j]) then
		noms[j].gone = true; -- Om nom
	      end
	    end
	  end
	  
	  for i = 0, nfood-1, 1 do
	    if noms[i].y > th then
	      noms[i].gone = true
	    end 
	  end
	  
	  
	  -- Clear out the old food
	  local nNewNoms = 0;
	  local newNoms = {};
	  for i = 0, nfood-1, 1 do
	    if not noms[i].gone then
	       newNoms[nNewNoms] = noms[i];
	       nNewNoms = nNewNoms + 1;
	    end
	  end
	  noms = newNoms;
	  nfood = nNewNoms;
	  
	  -- FEEED!
	  if redstone.getInput("left") then
	    noms[nfood] = initFood(tw, th, fishTime)
	    nfood = nfood + 1;
	  end

	  trm.setCursorPos(1,1);
	  trm.write("Food: " .. nfood)
	      
	  -- Tick Tock
	  fishTime = fishTime + 1;
	  os.sleep(0.25);
	end
end

local terminal = term;
local termWidth;
local termHeight;
termWidth, termHeight = terminal.getSize()

simulate({
	Term = terminal,
	Width = termWidth,
	Height = termHeight,
	NFish = 9
});