raymarch.lua

   1 require "Vector"
   2 local V = Vector
   3
   4 require "Primitives"
   5 local P = Primitives
   6
   7 require "Operations"
   8 local O = Operations
   9
  10 require "Textures"
  11 local T = Textures
  12
  13 local eps = 0.01
  14 local max_dist2 = 20^2
  15 local bg_col = {0.1,0.1,0.1}
  16
  17 local function calculate_normal(sdf, l)
  18    local delta = 1e-3;
  19    return V.new{sdf(l+V.x*delta).dist-sdf(l-V.x*delta).dist,
  20                 sdf(l+V.y*delta).dist-sdf(l-V.y*delta).dist,
  21                 sdf(l+V.z*delta).dist-sdf(l-V.z*delta).dist}/(2*delta)
  22 end
  23
  24 local function march(start, location, ray_dir, sdf, count)
  25    if V.norm2(location-start) > max_dist2 then
  26       return bg_col
  27    end
  28
  29    local p = sdf(location)
  30    if p.dist < eps then
  31       return p.texture(location, ray_dir, calculate_normal(sdf, location-(ray_dir*eps)), count)
  32    else
  33       return march(start, location + ray_dir*p.dist,
  34                    ray_dir, sdf, count+1)
  35    end
  36 end
  37
  38 local function render(scene, width, height, filename)
  39    print("Rendering to file " .. filename .. "...")
  40
  41    local f = io.open(filename, "w")
  42    f:write("P3 ", width, " ", height, " 255\n")
  43
  44    local c = scene.camera
  45    local cam_dir = V.normalize(c.point_at - c.location)
  46    local right = V.normalize(c.right)
  47    local up = V.cross(right,cam_dir)
  48    local aspect = height/width;
  49
  50    local normalize = V.normalize -- optimization
  51
  52    for y=1,height do
  53
  54       if y % math.floor(height/10) == 0 then
  55          print(y/math.floor(height/10) * 10 .. "%")
  56       end
  57
  58       local rayy = cam_dir + up*((0.5 - y/height)*c.fov*aspect)
  59
  60       for x=1,width do
  61          local ray_dir = normalize(rayy + right*((x/width - 0.5)*c.fov))
  62          local col = march(c.location, c.location, ray_dir, scene.sdf, 0)
  63          col = {math.min(col[1]*255, 255),
  64                 math.min(col[2]*255, 255),
  65                 math.min(col[3]*255, 255)}
  66
  67          f:write(math.floor(col[1]), " ", math.floor(col[2]), " ", math.floor(col[3]), " ")
  68       end
  69       f:write("\n")
  70    end
  71    f:write("\n")
  72
  73    f:close()
  74
  75    print("done")
  76 end
  77
  78
  79
  80 local scene = {
  81    sdf =
  82       O.union(
  83          P.make_sphere(V.new{0,0,0}, 1,
  84                        T.make_phong_texture({V.new{2,-3,1}},
  85                           T.make_solid_pigment({0,1,0}),
  86                           0.2, 0.7, 1.0, 100)),
  87          P.make_plane(V.new{0,0,-3.0}, V.new{0,0,1},
  88                       T.make_flat_texture(T.make_checkered_pigment({0,0,1}, {1,1,1})))),
  89
  90    camera = {location = V.new{0,-5,0},
  91              point_at = V.new{0,0,0},
  92              right = V.new{1,0,0},
  93              fov = 1}}
  94
  95 render(scene, 640, 480, "test.ppm")