Lodev PICO-8

raycaster.p8

player = {
    posX=1,
    posY=1,
    dirX = -1,
    dirY = 0,
    planeX=0, 
    planeY=0.66
}

function raycast()
	for i=0,128 do
        -- x coord in camera space
        local cameraX = 2 * i / 128 - 1
        local rayDirX = player.dirX + player.planeX * cameraX
        local rayDirY = player.dirY + player.planeY * cameraX

        local mapX = player.posX
        local mapY = player.posY
     
        local sideDistX
        local sideDistY

        -- correction to avoud 0 div
        if rayDirX == 0 then rayDirX = 32000 end
        if rayDirY == 0 then rayDirX = 32000 end

        local deltaDistX = abs(1 / rayDirX)
        local deltaDistY = abs(1 / rayDirY)

        local stepX, stepY
        local perpWallDist
        local hit = 0
        local side

      


        -- inital step and sidedist calc
        if (rayDirX < 0) then
            stepX = -1
            sideDistX = (player.posX - mapX) * deltaDistX
        else
            stepX = 1
            sideDistX = (mapX + 1 - player.posX) * deltaDistX
        end
        if (rayDirY < 0) then
            stepY = -1
            sideDistY = (player.posY - mapY) * deltaDistY
        else
            stepY = 1
            sideDistY = (mapY + 1 - player.posY) * deltaDistY
        end
        -- perform DDA
        while (hit == 0) do
            
            --printh(sideDistX)
            --printh(sideDistY)

            if sideDistX < sideDistY then
                -- step in x
                sideDistX += deltaDistX
                mapX += stepX
                side = 0
            else
                sideDistY += deltaDistY
                mapY+=stepY
                side=1
            end
            if wall_check_in_dda(mapX, mapY) then hit = 1 end

        end

        -- distance calculation from camera plane (this abvoids fisheye problem)
        if side == 0 then 
            perpWallDist = sideDistX - deltaDistX
        else
            perpWallDist = sideDistY - deltaDistY
        end

        -- calc line height
        lineHeight = 128/perpWallDist

        -- calc lowesr and highest pixel to fill
        drawStart = -lineHeight/2 + 64
        if drawStart < 0 then drawStart = 0 end

        drawEnd = lineHeight/2 + 64
        if drawEnd >=127 then drawEnd = 127 end

        local colorData = { {5,1},{11,3},{12,13},{8,2},{10,9}}
        local mapTile = mget(mapX, mapY)
        printh(mapTile)
        local colorToUse = colorData[mapTile-63][side+1]
        line(i, drawStart, i, drawEnd, colorToUse)

    end
end