X-Git-Url: https://thelambdalab.xyz/gitweb/index.cgi?a=blobdiff_plain;f=Primitives.lua;h=1648392041b5ea7f95491db8d3d60573337a5167;hb=refs%2Fheads%2Fmaster;hp=c13966be230c0d4eb89bd3eee180010531a04f2f;hpb=46c0ad2326b3d4edae71c00b6f4fcecb5eff4e07;p=raymarcher.git

diff --git a/Primitives.lua b/Primitives.lua
index c13966b..1648392 100644
--- a/Primitives.lua
+++ b/Primitives.lua
@@ -24,11 +24,47 @@ local function make_pipe(centre, radius, axis, texture)
    end
 end
 
+local function make_mandelbulb(centre, max_iter, power, texture)
+   return function(p)
+      local z = p - centre
+      local dr = 1.0
+      local r = 0.0
+
+      for i=1,max_iter do
+         r = V.norm(z)
+         if r>2.0 then
+            break
+         end
+         
+         -- convert to polar coordinates
+         theta = math.acos(z[3]/r)
+         phi = math.atan(z[2],z[1])
+         dr =  math.pow(r, power-1.0)*power*dr + 1.0
+         
+         -- scale and rotate the point
+         zr = math.pow(r, power)
+         theta = theta*power
+         phi = phi*power
+         
+         -- convert back to cartesian coordinates
+         z = V.new{math.sin(theta)*math.cos(phi),
+                   math.sin(phi)*math.sin(theta),
+                   math.cos(theta)} * zr
+         z = z + p
+      end
+   
+      return {dist = 0.5*math.log(r)*r/dr,
+              texture = texture}
+   end
+end
+
+
 
 Primitives = {
    make_sphere = make_sphere,
    make_plane = make_plane,
-   make_pipe = make_pipe
+   make_pipe = make_pipe,
+   make_mandelbulb = make_mandelbulb
 }
 
 return Primitives