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 = 30^2
  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,
  32                        calculate_normal(sdf, location-(ray_dir*eps)),
  33                        count, sdf)
  34    else
  35       return march(start, location + ray_dir*p.dist,
  36                    ray_dir, sdf, count+1)
  37    end
  38 end
  39
  40 local function render(scene, width, height, filename)
  41    print("Rendering to file " .. filename .. "...")
  42
  43    local f = io.open(filename, "w")
  44    f:write("P3 ", width, " ", height, " 255\n")
  45
  46    local c = scene.camera
  47    local cam_dir = V.normalize(c.point_at - c.location)
  48    local right = V.normalize(c.right)
  49    local up = V.cross(right,cam_dir)
  50    local aspect = height/width;
  51
  52    local normalize = V.normalize -- optimization
  53
  54    for y=1,height do
  55
  56       if y % math.floor(height/10) == 0 then
  57          print(y/math.floor(height/10) * 10 .. "%")
  58       end
  59
  60       local rayy = cam_dir + up*((0.5 - y/height)*c.fov*aspect)
  61
  62       for x=1,width do
  63          local ray_dir = normalize(rayy + right*((x/width - 0.5)*c.fov))
  64          local col = march(c.location, c.location, ray_dir, scene.sdf, 0)
  65          col = {math.min(col[1]*255, 255),
  66                 math.min(col[2]*255, 255),
  67                 math.min(col[3]*255, 255)}
  68
  69          f:write(math.floor(col[1]), " ", math.floor(col[2]), " ", math.floor(col[3]), " ")
  70       end
  71       f:write("\n")
  72    end
  73    f:write("\n")
  74
  75    f:close()
  76
  77    print("done")
  78 end
  79
  80
  81 local lights = {V.new{3,-3,1}}
  82
  83 local scene = {
  84    sdf =
  85       O.union(
  86          O.diff(
  87             O.diff(
  88                O.diff(
  89                   P.make_sphere(V.new{0,0,0}, 1,
  90                                 T.make_phong_texture(lights,
  91                                                      T.make_solid_pigment({0,1,0}),
  92                                                      0.2, 0.7, 1.0, 100)),
  93                   P.make_sphere(V.new{0,0,0}, 0.8)),
  94                P.make_pipe(V.new{0,0,0}, 0.5, V.new{0,1,0})),
  95             P.make_pipe(V.new{0,0,0}, 0.5, V.new{1,0,0})),
  96
  97          P.make_plane(V.new{0,0,-1.0}, V.new{0,0,1},
  98                       T.make_phong_texture(lights,
  99                          T.make_checkered_pigment({0.5,0,0.2}, {1,1,1}),
 100                          0.2, 1.0, 0, 1))),
 101                       -- T.make_flat_texture(T.make_checkered_pigment({0,0,1}, {1,1,1})))),
 102
 103    camera = {location = V.new{2,-5,1},
 104              point_at = V.new{0,0,0},
 105              right = V.x,
 106              fov = 1}}
 107
 108 -- render(scene, 320, 200, "test.ppm")
 109 render(scene, 640, 480, "test.ppm")