Simple Raycasting

raycast.lua

-- A simple raycasting engine
-- Uses LuaPlayer as framework

map = {
width = 10,
height = 10,
--mapping decor : 1 = Wall, 0 = No Wall
{1,1,1,1,1,1,1,1,1,1},
{1,0,0,0,0,0,0,0,0,1},
{1,0,0,1,1,1,1,0,0,1},
{1,0,0,0,0,0,0,0,0,1},
{1,1,0,0,0,0,0,0,1,1},
{1,0,0,0,1,0,1,0,0,1},
{1,0,0,0,1,0,1,0,0,1},
{1,0,0,0,1,0,1,0,0,1},
{1,0,0,1,1,0,0,0,0,1},
{1,1,1,1,1,1,1,1,1,1},
}

--Player's Starting Position
posx = 2
posy = 3

--Initial Directior Vector, Plane Setting and Time Settings
dirx = 1
diry = 0
planex = 0
planey = 0.66

move = 1
rotation = math.pi/2
direction = 1

timer = 0
oldtime = 10

--screen Dimensions
screenx = 480
screeny = 272

		colorRoof = Color.new(30, 70, 30)
		colorSky = Color.new(30, 70, 200)
		colorStripes = Color.new(70, 56, 90)
		
while true do
screen:clear()
pad = Controls.read()

	x=0
	
	for x = 0,screenx do
	camx = 2*x/screenx - 1
	rayposx = posx
	rayposy = posy
	raydirx = dirx + planex*camx
	raydiry = diry + planey*camx

	mapx = rayposx
	mapy = rayposy

	sidedistx = 0
	sidedisty = 0

	deltadistx = math.sqrt(1+(raydiry*raydiry)/(raydirx*raydirx))
	deltadisty = math.sqrt(1+(raydirx*raydirx)/(raydiry*raydiry))
	perp = 0

	stepx = 0
	stepy = 0
	hit = 0
	side = 0

		if raydirx < 0 then
		stepx = -1
		sidedistx = (rayposx - mapx)*deltadistx
		else stepx = 1
		sidedistx = (mapx + 1 - rayposx)*deltadistx end

		if raydiry < 0 then
		stepy = -1
		sidedisty = (rayposy - mapy)*deltadisty
		else stepy = 1
		sidedisty = (mapy + 1 - rayposy)*deltadisty end

		while hit == 0 do
			if sidedistx < sidedisty then
			sidedistx = sidedistx + deltadistx
			mapx = mapx + stepx
			side = 0
			else
			sidedisty = sidedisty + deltadisty
			mapy = mapy + stepy
			side = 1
			end
			
			if map[mapx][mapy] > 0 then hit = 1 end
		end
		
		if side == 0 then
		perp = math.abs((mapx - rayposx + (1-stepx)/2)/raydirx)
		else perp = math.abs((mapy - rayposy + (1-stepy)/2)/raydiry)
		end
		
		lineheight = math.abs(screeny/perp)	
		
		draw = -lineheight/2 + screeny/2
		if draw < 0 then draw = 0 end
		drawE = lineheight/2 + screeny/2
		if drawE >= screenx then drawE = screenx - 1 end
		

	    a = 65
	    b = 58
	    c = 63	

		if side == 1 then
		a = a-30
		b = b-30
		c = c-30
		end
		color = Color.new(a, b, c) 
		bandUp = screeny/2+drawE
		bandDown = screeny/2+draw    
	    screen:fillRect(x, draw, 1, drawE, color);
	    screen:fillRect(x, drawE, 1, 272, colorRoof);
	    screen:fillRect(x, 0, 1, draw, colorSky);
	    screen:fillRect(x, bandUp/2, 1, 1,colorStripes)
	    screen:fillRect(x, bandDown/2, 1, 1,colorStripes)
	    screen:fillRect(x, screeny/2, 1, 1,colorStripes)
	end	
	

	
if pad:up() then
timer = timer+1
if timer >= oldtime then
      if map[posx + dirx * move][posy] == 0 then posx = posx + dirx * move end
      if map[posx][posy + diry * move] == 0 then posy = posy + diry * move end
timer = 0
end
end

if pad:down() then
timer = timer+1
if timer >= oldtime then
      if map[posx - dirx * move][posy] == 0 then posx = posx - dirx * move end
      if map[posx][posy - diry * move] == 0 then posy = posy - diry * move end
timer = 0
end
end
if pad:right() then
timer = timer+1.5
if timer >= oldtime then
      --both camera direction and camera plane must be rotated
      oldDirX = dirx;
      dirx = dirx * math.cos(-rotation) - diry * math.sin(-rotation);
      diry = oldDirX * math.sin(-rotation) + diry * math.cos(-rotation);
      oldPlaneX = planex;
      planex = planex * math.cos(-rotation) - planey * math.sin(-rotation);
      planey = oldPlaneX * math.sin(-rotation) + planey * math.cos(-rotation);
direction = direction + 1
timer = 0
end
end
if pad:left() then
timer = timer+1.5
if timer >= oldtime then
      --both camera direction and camera plane must be rotated
      oldDirX = dirx;
      dirx = dirx * math.cos(rotation) - diry * math.sin(rotation);
      diry = oldDirX * math.sin(rotation) + diry * math.cos(rotation);
      oldPlaneX = planex;
      planex = planex * math.cos(rotation) - planey * math.sin(rotation);
      planey = oldPlaneX * math.sin(rotation) + planey * math.cos(rotation);
direction = direction - 1
timer = 0
end
end
	

	
	
screen.waitVblankStart()
screen.flip()	
end