wolf3d proof of concept (cc lua)

local buffer=term
local loadedAPI=false

if redirect then
  buffer=redirect.createRedirectBuffer()
  print("redirect API found, using buffer")
else
  local pe=printError
  rawset(_G,"printError",error)
  local ok, err=pcall(os.loadAPI,"redirect")
  if not ok then
    print("trying "..shell.dir().."/redirect")
    ok,err=pcall(os.loadAPI,shell.dir().."/redirect")
  end
  if ok then
    print("Loaded redirect API, using buffer")
    buffer=redirect.createRedirectBuffer()
    loadedAPI=true
  else
    print("redirect API not found or could not be loaded, drawing directly; this may cause flickering.")
  end
  rawset(_G,"printError",pe)

end


local mapW, mapH=16,32
local map={
  "1111111111111111",
  "1   12         1",
  "1 111111111111 1",
  "1 1      1   1 1",
  "1 1 1111 1 1 1 1",
  "1 1   1  1 1   1",
  "1 111 111111 111",
  "1   1          1",
  "111 11111111 1 1",
  "1 1          1 1",
  "1 111111111111 1",
  "1   1 1    1   1",
  "1 111 1 1111 111",
  "1     1    1   1",
  "1 11111111 111 1",
  "1              1",
  "1111114  4111111",
  "1              1",
  "1              1",
  "1  3  3  3  3  1",
  "1              1",
  "1              1",
  "1  2  5  5  2  1",
  "1              1",
  "1              1",
  "1  2  5  5  2  1",
  "1              1",
  "1              1",
  "1  3  2  2  3  1",
  "1              1",
  "1              1",
  "1111111111111111",
}

local colorSchemes = {
  {0,8}, --white+gray
  {3,11}, --blue
  {6,14}, --red
  {5,13}, --green
  {4,1}, --yellow/orange
}


local function cast(cx,cy,angle)
  --direction vector
  local vx,vy=math.cos(angle), math.sin(angle)
  local slope=vy/vx
  --next distance, x and y axis points
  local ndx, ndy
  --steps, distance and block
  local dsx, dsy, bsx, bsy
  if vx<0 then
    local x=(cx%1)
    bsx=-1
    ndx=math.sqrt(x*x*(1+slope*slope))
    dsx=math.sqrt((1+slope*slope))
  else
    local x=1-(cx%1)
    bsx=1
    ndx=math.sqrt(x*x*(1+slope*slope))
    dsx=math.sqrt((1+slope*slope))
  end

  if vy<0 then
    local y=(cy%1)
    bsy=-1
    ndy=math.sqrt(y*y*(1+1/(slope*slope)))
    dsy=math.sqrt((1+1/(slope*slope)))
  else
    local y=1-(cy%1)
    bsy=1
    ndy=math.sqrt(y*y*(1+1/(slope*slope)))
    dsy=math.sqrt((1+1/(slope*slope)))
  end

  local x,y=math.floor(cx),math.floor(cy)
  while x>0 and x<=mapW and y>0 and y<=mapH do
    local hitD
    local isX
    if ndx<ndy then
      --x crossing is next
      x=x+bsx
      isX=true
      hitD=ndx
      ndx=ndx+dsx
    else
      y=y+bsy
      isX=false
      hitD=ndy
      ndy=ndy+dsy
    end
    local wall=map[y]:sub(x,x)
    if wall~=" " then

      return colorSchemes[tonumber(wall)][isX and 1 or 2], hitD
    end
  end
end

local w,h=term.getSize()
local centerX, centerY=math.floor((w+1)/2), math.floor((h+1)/2)

local px, py=9,25
local dir=0
local fx,fy
local speed=.1
local turnSpeed=4

local function turn(amt)
  dir=dir+amt
  fx,fy=math.cos(math.rad(dir)), math.sin(math.rad(dir))
end

turn(0)

--build table of angles and base distances per scanline
local screenDist=.55*w
local scan={}

for x=1,w do
  local t={}
  scan[x]=t
  t.angle=math.atan2(x-centerX,screenDist)
  t.dist=((x-centerX)^2+screenDist^2)^.5/screenDist
end

local function redraw()
  if buffer.isBuffer then
    term.redirect(buffer)
  end
  for x=1,w do
    local wall,dist=cast(px,py,math.rad(dir)+scan[x].angle)
    if wall then
      --calc wall height based on distance
      local height=scan[x].dist/dist
      height=math.floor(math.min(height*centerY,(h+1)/2))
      term.setBackgroundColor(colors.gray)
      for y=1,(h+1)/2-height-1 do
        term.setCursorPos(x,y)
        term.write(" ")
      end
      for y=centerY+height+1,h do
        term.setCursorPos(x,y)
        term.write(" ")
      end
      term.setBackgroundColor(2^wall)
      for y=centerY-height,centerY+height do
        term.setCursorPos(x,y)
        term.write(" ")
      end
    end
  end
  if buffer.isBuffer then
    term.restore()
    buffer.blit()
  end
end

local function clampCollision(x,y,radius)
  --am I *in* a block?
  local gx,gy=math.floor(x),math.floor(y)
  if map[gy]:sub(gx,gx)~=" " then
    --I am. Complete fail, do nothing.
    return x,y
  end

  --ok, check the neighbors.
  local right=math.floor(x+radius)>gx
  local left=math.floor(x-radius)<gx
  local front=math.floor(y-radius)<gy
  local back=math.floor(y+radius)>gy

  local pushed=false

  if right and map[gy]:sub(gx+1,gx+1)~=" " then
    --push left
    pushed=true
    x=gx+1-radius
  elseif left  and map[gy]:sub(gx-1,gx-1)~=" " then
    --push right
    pushed=true
    x=gx+radius
  end

  if front and map[gy-1]:sub(gx,gx)~=" " then
    --push back
    pushed=true
    y=gy+radius
  elseif back and map[gy+1]:sub(gx,gx)~=" " then
    --push forward
    pushed=true
    y=gy+1-radius
  end

  --if I wasn't pushed out on any side, I might be hitting a corner
  if not pushed then
    --square rad
    local r2=radius^2
    local pushx,pushy=0,0
    if left then
      if front and map[gy-1]:sub(gx-1,gx-1)~=" " then
        --check front-left
        local dist2=(gx-x)^2+(gy-y)^2
        if dist2<r2 then
          local pushd=(r2-dist2)/2^.5
          pushx,pushy=pushd,pushd
        end
      elseif back and map[gy+1]:sub(gx-1,gx-1)~=" " then
        local dist2=(gx-x)^2+(gy+1-y)^2
        if dist2<r2 then
          local pushd=(r2-dist2)/2^.5
          pushx,pushy=pushd,-pushd
        end
      end
    elseif right then
      if front and map[gy-1]:sub(gx+1,gx+1)~=" " then
        --check front-left
        local dist2=(gx+1-x)^2+(gy-y)^2
        if dist2<r2 then
          local pushd=(r2-dist2)/2^.5
          pushx,pushy=-pushd,pushd
        end
      elseif back and map[gy+1]:sub(gx+1,gx+1)~=" " then
        local dist2=(gx+1-x)^2+(gy+1-y)^2
        if dist2<r2 then
          local pushd=(r2-dist2)/2^.5
          pushx,pushy=-pushd,-pushd
        end
      end
    end
    x=x+pushx
    y=y+pushy
  end

  return x,y
end



print([[
Basic wolfenstein 3d-style rendering engine proof-of-concept
controls:
asdw - move
left/right - turn left/right
q - quit

Press any key to begin...]])

os.pullEvent("key")

local frameTimer=os.startTimer(0.5)
local prevTick=0
local dirty=true
while true do
  px,py=clampCollision(px,py,.25)
  if dirty then
    redraw()
    dirty=false
  end

  local e={os.pullEvent()}
  if e[1]=="key" then
    if e[2]==keys.left then
      turn(-turnSpeed)
      dirty=true
    elseif e[2]==keys.right then
      turn(turnSpeed)
      dirty=true
    elseif e[2]==keys.up or e[2]==keys.w then
      px=px+fx*speed
      py=py+fy*speed
      dirty=true
    elseif e[2]==keys.down or e[2]==keys.s then
      px=px-fx*speed
      py=py-fy*speed
      dirty=true
    elseif e[2]==keys.a then
      px=px+fy*speed
      py=py-fx*speed
      dirty=true
    elseif e[2]==keys.d then
      px=px-fy*speed
      py=py+fx*speed
      dirty=true
    elseif e[2]==keys.q then
      break
    end
  end
end


if loadedAPI then
  os.unloadAPI("redirect")
end

term.setBackgroundColor(colors.black)
os.pullEvent()
term.scroll(1)
term.setCursorPos(1,19)