From f385f4b589fc49dc55c3ce4447b4450c3e515123 Mon Sep 17 00:00:00 2001
From: Tim Vaughan <timv@ughan.xyz>
Date: Sat, 18 Mar 2023 19:47:27 +0100
Subject: [PATCH] Shifted mandelbulb sdf out to primitives.

---
 Colours.lua    | 12 ++++++++++++
 Primitives.lua | 35 +++++++++++++++++++++++++++++++++++
 mandelbulb.lua | 45 ++++++---------------------------------------
 3 files changed, 53 insertions(+), 39 deletions(-)
 create mode 100644 Colours.lua

diff --git a/Colours.lua b/Colours.lua
new file mode 100644
index 0000000..8a71cbe
--- /dev/null
+++ b/Colours.lua
@@ -0,0 +1,12 @@
+--- Some pre-defined colours
+
+Colours = {
+   red = {1,0,0},
+   green = {0,1,0},
+   blue = {0,0,1},
+   yellow = {1,1,0},
+   magenta = {1,0,1},
+   cyan = {0,1,1}
+}
+
+return Colours
diff --git a/Primitives.lua b/Primitives.lua
index c13966b..b1efbfb 100644
--- a/Primitives.lua
+++ b/Primitives.lua
@@ -24,6 +24,41 @@ 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,
diff --git a/mandelbulb.lua b/mandelbulb.lua
index eca6da2..7d7a011 100644
--- a/mandelbulb.lua
+++ b/mandelbulb.lua
@@ -12,47 +12,14 @@ local T = Textures
 
 require "Render"
 
-local function make_mandelbulb(max_iter, power, texture)
-   return function(p)
-      local z = V.new(p)
-      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
 
 local scene = {
    -- sdf = make_mandelbulb(T.make_count_texture(0.1)),
-   sdf = make_mandelbulb(100, 8,
-                         T.make_phong_texture(
-                            {V.new{3,-5,3}},
-                            T.make_solid_pigment{0,0.5,1.0},
-                            0.1, 1.0, 0.0, 30)),
+   sdf = P.make_mandelbulb(V.origin, 100, 8,
+                           T.make_phong_texture(
+                              {V.new{3,-5,3}},
+                              T.make_solid_pigment{0,0.5,1.0},
+                              0.1, 1.0, 0.0, 30)),
 
    camera = {location = V.new{0,-5,0},
              point_at = V.origin,
@@ -61,4 +28,4 @@ local scene = {
 
 Render.eps = 0.001
 Render.bg_col = {0,0,0}
-Render.render(scene, 640, 480, "out/mandelbulb.ppm")
+Render.render(scene, 2560, 1440, "out/mandelbulb.ppm")
-- 
2.20.1