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_dist = 50
  15 local bg_col = {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(location, ray_dir, sdf, count)
  25    local p = sdf(location)
  26    if p.dist < eps then
  27       return p.texture(location, ray_dir, calculate_normal(sdf, location-(ray_dir*eps)), count)
  28    elseif p.dist > max_dist then
  29       return bg_col
  30    else
  31       return march(location + ray_dir*p.dist,
  32                    ray_dir, sdf, count+1)
  33    end
  34 end
  35
  36 local function render(scene, width, height, filename)
  37    print("Rendering to file " .. filename .. "...")
  38
  39    local f = io.open(filename, "w")
  40    f:write("P3 ", width, " ", height, " 255\n")
  41
  42    local c = scene.camera
  43    local cam_dir = V.normalize(c.point_at - c.location)
  44    local right = V.normalize(c.right)
  45    local up = V.cross(right,cam_dir)
  46    local aspect = height/width;
  47
  48    for y=1,height do
  49
  50       if y % math.floor(height/10) == 0 then
  51          print(y/math.floor(height/10) * 10 .. "%")
  52       end
  53
  54       local rayy = cam_dir + up*((y/height - 0.5)*c.fov*aspect)
  55
  56       for x=1,width do
  57          local ray_dir = V.normalize(rayy + right*((x/width - 0.5)*c.fov))
  58          local col = march(c.location, ray_dir, scene.sdf, 0)
  59          col = {math.min(col[1]*255, 255),
  60                 math.min(col[2]*255, 255),
  61                 math.min(col[3]*255, 255)}
  62
  63          f:write(math.floor(col[1]), " ", math.floor(col[2]), " ", math.floor(col[3]), " ")
  64       end
  65       f:write("\n")
  66    end
  67    f:write("\n")
  68
  69    f:close()
  70
  71    print("done")
  72 end
  73
  74
  75
  76 local scene = {
  77    sdf = O.union(P.make_sphere(V.new{0,0,0}, 1,
  78                        -- T.make_count_texture()),
  79                                T.make_phong({V.new{2,-1,2}}, {0,1,0},
  80                                   1.0, 0.5, 100)),
  81                  P.make_sphere(V.new{1.5,0,1.0}, 0.5,
  82                                T.make_phong({V.new{2,-1,2}}, {0,0,1},
  83                                   1.0, 0.5, 100))),
  84
  85    camera = {location = V.new{0,-5,0},
  86              point_at = V.new{0,0,0},
  87              right = V.new{1,0,0},
  88              fov = 1}}
  89
  90 render(scene, 640, 480, "test.ppm")