+require "Vector"
+local V = Vector
+
+require "Primitives"
+local P = Primitives
+
+require "Textures"
+local T = Textures
+
+local eps = 0.01
+local max_dist = 50
+local bg_col = {1,0,1}
+
+local function calculate_normal(sdf, l)
+ local delta = 1e-3;
+ return -V.new{sdf(l+V.x*delta).dist-sdf(l-V.x*delta).dist,
+ sdf(l+V.y*delta).dist-sdf(l-V.y*delta).dist,
+ sdf(l+V.z*delta).dist-sdf(l-V.z*delta).dist}/(2*delta)
+end
+
+local function march(location, ray_dir, sdf, count)
+ local p = sdf(location)
+ if p.dist < eps then
+ return p.texture(location, ray_dir, calculate_normal(sdf, location-(ray_dir*eps)), count)
+ elseif p.dist > max_dist then
+ return bg_col
+ else
+ return march(location + ray_dir*p.dist,
+ ray_dir, sdf, count+1)
+ end
+end
+
+local function render(scene, width, height, filename)
+ print("Rendering to file " .. filename .. "...")
+
+ local f = io.open(filename, "w")
+ f:write("P3 ", width, " ", height, " 255\n")
+
+ local c = scene.camera
+ local cam_dir = V.normalize(c.point_at - c.location)
+ local right = V.normalize(c.right)
+ local up = V.cross(right,cam_dir)
+ local aspect = height/width;
+
+ for y=1,height do
+
+ if y % math.floor(height/10) == 0 then
+ print(y/math.floor(height/10) * 10 .. "%")
+ end
+
+ local rayy = cam_dir + up*((y/height - 0.5)*c.fov*aspect)
+
+ for x=1,width do
+ local ray_dir = V.normalize(rayy + right*((x/width - 0.5)*c.fov))
+ local col = march(c.location, ray_dir, scene.sdf, 0)
+ col = {math.min(col[1]*255, 255),
+ math.min(col[2]*255, 255),
+ math.min(col[3]*255, 255)}
+
+ f:write(math.floor(col[1]), " ", math.floor(col[2]), " ", math.floor(col[3]), " ")
+ end
+ f:write("\n")
+ end
+ f:write("\n")
+
+ f:close()
+
+ print("done")
+end
+
+local scene = {
+ sdf = P.make_sphere(V.new{0,0,0}, 1,
+ T.make_phong({V.new{2,0,2}}, {0,1,0}, 1.0, 0.5, 100)),
+ camera = {location = V.new{0,-5,0},
+ point_at = V.new{0,0,0},
+ right = V.new{1,0,0},
+ fov = 1}}
+
+render(scene, 640, 480, "test.ppm")