Render.lua

   1 -- Main rendering functions
   2
   3 require "Vector"
   4 local V = Vector
   5
   6 require "Primitives"
   7 local P = Primitives
   8
   9 require "Operations"
  10 local O = Operations
  11
  12 require "Textures"
  13 local T = Textures
  14
  15 local eps = 0.01
  16 local max_dist2 = 30^2
  17 local bg_col = {0.1,0.1,0.1}
  18
  19 local function calculate_normal(sdf, l)
  20    local delta = 1e-3;
  21    return V.new{sdf(l+V.x*delta).dist-sdf(l-V.x*delta).dist,
  22                 sdf(l+V.y*delta).dist-sdf(l-V.y*delta).dist,
  23                 sdf(l+V.z*delta).dist-sdf(l-V.z*delta).dist}/(2*delta)
  24 end
  25
  26 local function march(start, location, ray_dir, sdf, count)
  27    if V.norm2(location-start) > max_dist2 then
  28       return bg_col
  29    end
  30
  31    local p = sdf(location)
  32    if p.dist < eps then
  33       return p.texture(location, ray_dir,
  34                        calculate_normal(sdf, location-(ray_dir*eps)),
  35                        count, sdf)
  36    else
  37       return march(start, location + ray_dir*p.dist,
  38                    ray_dir, sdf, count+1)
  39    end
  40 end
  41
  42 local function render(scene, width, height, filename)
  43    print("Rendering to file " .. filename .. "...")
  44
  45    local f = io.open(filename, "w")
  46    f:write("P3 ", width, " ", height, " 255\n")
  47
  48    local c = scene.camera
  49    local cam_dir = V.normalize(c.point_at - c.location)
  50    local right = V.normalize(c.right)
  51    local up = V.cross(right,cam_dir)
  52    local aspect = height/width;
  53
  54    local normalize = V.normalize -- optimization
  55
  56    for y=1,height do
  57
  58       if y % math.floor(height/10) == 0 then
  59          print(y/math.floor(height/10) * 10 .. "%")
  60       end
  61
  62       local rayy = cam_dir + up*((0.5 - y/height)*c.fov*aspect)
  63
  64       for x=1,width do
  65          local ray_dir = normalize(rayy + right*((x/width - 0.5)*c.fov))
  66          local col = march(c.location, c.location, ray_dir, scene.sdf, 0)
  67          col = {math.min(col[1]*255, 255),
  68                 math.min(col[2]*255, 255),
  69                 math.min(col[3]*255, 255)}
  70
  71          f:write(math.floor(col[1]), " ", math.floor(col[2]), " ", math.floor(col[3]), " ")
  72       end
  73       f:write("\n")
  74    end
  75    f:write("\n")
  76
  77    f:close()
  78
  79    print("done")
  80 end
  81
  82 Render = {
  83    eps = eps,
  84    max_dist2 = max_dist2,
  85    bg_col = bg_col,
  86    render = render
  87 }
  88
  89 return Render