Initial commit.

diff --git a/Primitives.lua b/Primitives.lua
new file mode 100644 (file)
index 0000000..88a3849
--- /dev/null
+++ b/Primitives.lua
@@ -0,0 +1,16 @@
+-- Geometric primitives for raymarching
+require "Vector"
+local V = Vector
+
+local function make_sphere(centre, radius, texture)
+      return function(p)
+         return {dist = V.norm(p-centre) - radius,
+                 texture = texture}
+      end
+end
+
+Primitives = {
+   make_sphere = make_sphere
+}
+
+return Primitives

diff --git a/Textures.lua b/Textures.lua
new file mode 100644 (file)
index 0000000..b1d1cb3
--- /dev/null
+++ b/Textures.lua
@@ -0,0 +1,27 @@
+-- Textures for raymarcher
+require "Vector"
+local V = Vector
+
+local function make_phong(lights, colour, amb, spec, shiny)
+   return function (location, ray_dir, normal, count)
+      local thiscol = {0, 0, 0}
+      local reflected_ray = V.normalize(normal*(ray_dir*normal*2) - ray_dir)
+      for _,light in ipairs(lights) do
+         local light_dir = V.normalize(light-location)
+         local Iamb = math.max(normal*light_dir, 0)
+         local Ispec = math.pow(math.max(light_dir*reflected_ray,0),shiny)
+            
+         thiscol[1] = thiscol[1] + colour[1]*Iamb*amb + Ispec*spec
+         thiscol[2] = thiscol[2] + colour[2]*Iamb*amb + Ispec*spec
+         thiscol[3] = thiscol[3] + colour[3]*Iamb*amb + Ispec*spec
+      end
+
+      return thiscol
+   end
+end
+   
+Textures = {
+   make_phong = make_phong
+}
+
+return Textures

diff --git a/Vector.lua b/Vector.lua
new file mode 100644 (file)
index 0000000..3f35b64
--- /dev/null
+++ b/Vector.lua
@@ -0,0 +1,107 @@
+-- Small package of 3D vector functions
+
+local mt = {}
+
+local function new(v)
+   local vec = {v[1], v[2], v[3]}
+   setmetatable(vec, mt)
+   return vec
+end
+
+local function addvec(v, w)
+   return new{v[1]+w[1], v[2]+w[2], v[3]+w[3]}
+end
+
+local function subvec(v, w)
+   return new{v[1]-w[1], v[2]-w[2], v[3]-w[3]}
+end
+
+local function addnum(v, n)
+   return new{v[1] + n, v[2] + n, v[3] + n}
+end
+
+local function subnum(v, n)
+   return new{v[1] - n, v[2] - n, v[3] - n}
+end
+
+local function addany(v, x)
+   if type(x) == "table" then
+      return addvec(v, x)
+   else
+      return addnum(v, x)
+   end
+end
+
+local function subany(v, x)
+   if type(x) == "table" then
+      return subvec(v, x)
+   else
+      return subnum(v, x)
+   end
+end
+
+local function scale(v, n)
+   return new{v[1]*n, v[2]*n, v[3]*n}
+end
+
+local function dot(v, w)
+   return v[1]*w[1] +v[2]*w[2] + v[3]*w[3]
+end
+
+local function mulany(v, x)
+   if type(x) == "table" then
+      return dot(v, x)
+   else
+      return scale(v, x)
+   end
+end
+
+local function cross(v, w)
+   return new {v[2]*w[3] - w[2]*v[3],
+               w[1]*v[3] - v[1]*w[3],
+               v[1]*w[2] - w[1]*v[2]}
+end
+
+local function scaleinv(v,n)
+   return new{v[1]/n, v[2]/n, v[3]/n}
+end
+
+local function neg(v)
+   return v*(-1)
+end
+
+local function norm2(v)
+   return dot(v,v)
+end
+
+local function norm(v)
+   return math.sqrt(norm2(v))
+end
+
+local function normalize(v)
+   return v/norm(v)
+end
+
+local function vectostring(v)
+   return "{" .. v[1] .. ", " .. v[2] .. ", " .. v[3] .. "}"
+end
+
+mt.__add = addany
+mt.__sub = subany
+mt.__mul = mulany
+mt.__div = scaleinv
+mt.__unm = neg
+mt.__tostring = vectostring
+
+Vector = {
+   new = new,
+   norm = norm,
+   norm2 = norm2,
+   cross = cross,
+   normalize = normalize,
+   x = new{1,0,0},
+   y = new{0,1,0},
+   z = new{0,0,1}
+}
+
+return Vector

diff --git a/raymarch.lua b/raymarch.lua
new file mode 100644 (file)
index 0000000..d296c23
--- /dev/null
+++ b/raymarch.lua
@@ -0,0 +1,79 @@
+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")