PICO-8 raycast test

raycast.p8

function _init()
 tile = 8
 gridlength = 8

 player = {
  x = 8,
  y = 8
 }

 map = {
  { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, },
  { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, },
  { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, },
  { 0, 0, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, },
  { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, },
  { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, },
  { 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, },
  { 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, },
  { 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, },
  { 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, },
  { 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, },
  { 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, },
  { 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, },
  { 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 0, },
  { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, },
  { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, }
 }

 rays = {}
end

getcellbypixelcoordinates = function(px, py, grid, tile)
 local x = flr(px / tile)
 local y = flr(py / tile)
 if x > 0 and x <= #grid and y > 0 and y <= #grid then
  return grid[x][y]
 else
  return nil
 end
end

outofbounds = function(px, py)
 if px < 0 or px > 128 + tile or
     py < 0 or py > 128 + tile then
  return true
 end
 return false
end

raycast = function(grid, tile, cellx, celly)
 local points = {}
 for angle = 0, 1, 0.05 do
  local radius = 1
  local targetx = cellx * tile
  local targety = celly * tile

  for i = 1, 128, 1 do
   if not outofbounds(targetx, targety) and
       getcellbypixelcoordinates(targetx, targety, grid, tile) == 0 then
    radius = radius + 1
    targetx = player.x * tile + cos(angle) * radius
    targety = player.y * tile + sin(angle) * radius
   end
  end
  add(points, { x = targetx, y = targety })
 end
 return points
end

function _update()
 rays = raycast(map,
  tile, player.x, player.y)

 if btn(2) then
  player.y = player.y - 0.1
 end
 if btn(3) then
  player.y = player.y + 0.1
 end
 if btn(0) then
  player.x = player.x - 0.1
 end
 if btn(1) then
  player.x = player.x + 0.1
 end
end

function _draw()
 cls()
 -- draw tiles.
 for x = 1, #map do
  for y = 1, #map do
   if map[x][y] == 0 then
    rect(
     x * tile - tile,
     y * tile - tile,
     x * tile + tile - tile,
     y * tile + tile - tile,
     1
    )
   else
    -- draw walls.
    rectfill(
     x * tile - tile,
     y * tile - tile,
     x * tile + tile - tile,
     y * tile + tile - tile,
     8
    )
   end
  end
 end

 if rays then
  for i = 1, #rays do
   line(
    player.x * tile - tile,
    player.y * tile - tile,
    rays[i].x - tile,
    rays[i].y - tile,
    12
   )
   circ(
    rays[i].x - tile,
    rays[i].y - tile,
    3, 8)
  end
 end

 -- player
 circ(
  player.x * tile - tile,
  player.y * tile - tile,
  3, 12)
end