[Lua] RayCaster

While I know this thread is somewhat dated, and the topic really has shifted more towards the CX's DRM, I thought I would highlight the importance of basic Lua optimizations.

I ran the code from the first page (slightly modified, included a timer call so I could get a consistent frame rate), and it ran at 4 to 5 frames per second.
I modify the code some (only localizes variables and common functions), and then I can get 6 - 7 frames per second.
This doesn't change the algorithm at all, though that could probably be improved.

Code: Select All | Copy To Clipboard

local timer_stop = timer.stop;
local timer_start = timer.start;
local window = platform.window;
local invalidate = window.invalidate;
local w, h, planeX, planeY, map;


function on.timer()
 timer_stop();
 invalidate(window);
end

local math_abs = math.abs;
local math_floor = math.floor;
local math_cos, math_sin = math.cos, math.sin;

local function racine(a)
 local x=1
 local y=0.5*(1+a)
 while math_abs(y-x)>0.001 do
  x=y
  y=0.5*(x+a/x)
 end
 return y
end

local function renderMap(gc,map,w,h,camera)
 local math_cos, math_sin = math_cos, math_sin;
 local dirX, dirY, rayPosX, rayPosY, rayDirX, rayDirY, mapX, mapY, deltaDistX,
 deltaDisY, hit, stepX, sideDistX, stepY, sideDistY;
 for x=0,w,2 do
   dirX=math_cos(camera[3])
   dirY=math_sin(camera[3])
  planeX=math_cos(camera[3]-1.5707963267949)
  planeY=math_sin(camera[3]-1.5707963267949)
   cameraX=(x*2/w)-1
   rayPosX=camera[1]
   rayPosY=camera[2]
   rayDirX=dirX+planeX*cameraX
   rayDirY=dirY+planeY*cameraX
   mapX=math_floor(rayPosX)
   mapY=math_floor(rayPosY)
   deltaDistX=racine(1+(rayDirY*rayDirY)/(rayDirX*rayDirX))
   deltaDistY=racine(1+(rayDirX*rayDirX)/(rayDirY*rayDirY))
   hit=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

  local perpWallDist;

  if side==0 then
    perpWallDist=math_abs((mapX-rayPosX+(1-stepX)/2)/rayDirX)
  else
   perpWallDist=math.abs((mapY-rayPosY+(1-stepY)/2)/rayDirY)
  end
  local hauteurLigne=math.abs(math_floor(h/perpWallDist))
  local drawStart=math_floor(-hauteurLigne/2+h/2)
  local drawEnd=math_floor(hauteurLigne/2+h/2)
  if drawStart<0 then
   drawStart=0
  end
  if drawEnd>=h then
   drawEnd=h-1
  end

  gc:setColorRGB(10,10,10)
  if side==1 then
   gc:setColorRGB(100,100,100)
  end
  gc:fillRect(x,drawStart,2,drawEnd-drawStart)
 end
end


local menu;
function on.escapeKey()
 menu=1
 invalidate(window);
end
on.escapeKey()

function on.enterKey()
 menu=nil
 --fovy=60
 camera={10,10,0.05}
 w=320 h=240
 planeX=0 planeY=1
 map={{1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1},{1,0,0,1,0,0,1,0,0,0,0,0,0,0,0,1},{1,0,0,0,0,0,1,0,0,0,0,0,0,0,0,1},{1,0,0,0,0,0,1,0,0,1,1,1,1,1,1,1},{1,0,0,1,1,1,1,0,0,1,0,0,0,0,0,1},{1,0,0,1,0,0,0,0,0,1,0,0,0,0,0,1},{1,0,0,0,0,0,0,0,0,1,0,0,1,0,0,1},{1,0,0,0,0,0,1,0,0,1,0,0,1,0,0,1},{1,1,1,1,1,1,1,0,0,1,0,0,1,0,0,1},{1,0,0,1,0,0,0,0,0,0,0,0,1,1,1,1},{1,0,0,1,0,0,0,0,0,0,0,0,0,0,0,1},{1,0,0,1,1,1,1,1,1,1,1,1,1,0,0,1},{1,0,0,1,0,0,0,0,1,0,0,0,0,0,0,1},{1,0,0,1,0,0,0,0,1,0,0,0,0,0,0,1},{1,0,0,1,1,1,0,0,1,1,1,1,1,0,0,1},{1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1},{1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1},{1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1}}
 invalidate(window);
end

function on.arrowKey(ar)
 turn=nil
 if ar=="right" then
  camera[3]=camera[3]-0.1
 end
 if ar=="left" then
  camera[3]=camera[3]+0.1
 end
 if ar=="up" then
  if map[math_floor(camera[1]+math_cos(camera[3])/3)][math_floor(camera[2]+math_sin(camera[3])/3)]==0 then
   camera[1]=camera[1]+math_cos(camera[3])/3
   camera[2]=camera[2]+math_sin(camera[3])/3
  end
 end
 if ar=="down" then
  if map[math_floor(camera[1]-math_cos(camera[3])/4)][math_floor(camera[2]-math_sin(camera[3])/4)]==0 then
   camera[1]=camera[1]-math_cos(camera[3])/4
   camera[2]=camera[2]-math_sin(camera[3])/4
  end

 end
 invalidate(window);
end

local milli = timer.getMilliSecCounter;
local last = 0;

function on.paint(gc)
 if menu then
  gc:setColorRGB(0,0,255)
  gc:setFont("sansserif","r",30)
  gc:drawString("RayCaster Demo",30,0,"top")
  gc:setFont("serif","b",10)
  gc:drawString("Press Enter to start",100,100,"top")
 else
  gc:setColorRGB(200,200,200)
  gc:fillRect(0,0,platform.window:width(),platform.window:height())
  renderMap(gc,map,platform.window:width(),platform.window:height(),camera)
 end
 gc:setColorRGB(0,0,0)
 gc:setFont("sansserif","r",8)
 gc:drawString("FPS: " .. tostring(1000/(milli()-last)),10,200,"top")
 last = milli();
 timer_start(0.01);
end