X-Git-Url: https://thelambdalab.xyz/gitweb/index.cgi?a=blobdiff_plain;f=Textures.lua;h=2b2e70151f24eaec9150152a01ebc27792ccab5c;hb=f564e0e7248f977ea2397ea49e3d2e1804a65f7c;hp=3a4abaf0a453d45a5bbc58247070cd7a63c11f7f;hpb=c91cd134a1333e89ffddceb0b4a3d21c961f4fd5;p=raymarcher.git

diff --git a/Textures.lua b/Textures.lua
index 3a4abaf..2b2e701 100644
--- a/Textures.lua
+++ b/Textures.lua
@@ -1,8 +1,9 @@
 -- Textures for raymarcher
+
 require "Vector"
 local V = Vector
 
-local function make_phong_texture(lights, pigment, amb, diff, spec, shiny)
+local function make_phong_texture(lights, mapped_pigment, amb, diff, spec, shiny)
    local normalize = V.normalize
 
    local eps = 0.0001
@@ -19,7 +20,7 @@ local function make_phong_texture(lights, pigment, amb, diff, spec, shiny)
    end
    
    return function (location, ray_dir, normal, count, sdf)
-      local colour = pigment(location[1],location[2])
+      local colour = mapped_pigment(location)
       local thiscol = {colour[1]*amb, colour[2]*amb, colour[3]*amb}
 
       local reflected_ray = ray_dir - normal*(ray_dir*normal*2)
@@ -47,20 +48,23 @@ local function make_count_texture(scale)
    end
 end
 
-local function make_flat_texture(pigment)
+local function make_flat_texture(mapped_pigment)
    return function (location, ray_dir, normal, count, sdf)
-      return pigment(location[1], location[2])
+      return mapped_pigment(location)
    end
 end
 
+
+-- Pigments
+
 local function make_solid_pigment(colour)
-   return function (x,y)
+   return function(x,y)
       return colour
    end
 end
 
 local function make_checkered_pigment(colour1, colour2)
-   return function (x,y)
+   return function(x,y)
       if (x%1 < 0.5 and y%1 < 0.5) or (x%1 > 0.5 and y%1 > 0.5) then
          return colour1
       else
@@ -69,14 +73,13 @@ local function make_checkered_pigment(colour1, colour2)
    end
 end
 
-local function make_mandelbrot_pigment(set_colour, max_iter)
+local function make_mandelbrot_pigment(set_pigment, nonset_pigment, max_iter)
 
    local function get_col(x,y,cx,cy,iter)
       if iter == 0 then
-         return set_colour
+         return set_pigment(cx, cy)
       elseif x^2 + y^2 > 4 then
-         local I = iter/max_iter
-         return {I,I,1-I}
+         return nonset_pigment(cx, cy)
       else
          return get_col(x^2 - y^2 + cx,
                         2*x*y + cy,
@@ -85,7 +88,30 @@ local function make_mandelbrot_pigment(set_colour, max_iter)
    end
 
    return function (x,y)
-      get_col(0,0,x,y,max_iter)
+      return get_col(0,0,x,y,max_iter)
+   end
+end
+
+-- Mapping functions
+
+-- These functions define mappings from 3D world coordinates to 2D
+-- texture/pigment coordinates
+
+local function map_rectangular(pigment, xvec, yvec)
+   return function(location)
+      return pigment(location*xvec, location*yvec)
+   end
+end
+
+local function map_spherical(pigment, centre, scale_theta, scale_phi)
+   return function(location)
+      local r = location-centre
+      local rnorm = V.norm(r)
+      
+      local phi = math.acos((V.z*r)/rnorm)
+      local theta = math.acos((V.x*r)/V.norm(V.cross(V.z,r)))
+
+      return pigment(theta*scale_theta/math.pi, phi*scale_phi/math.pi)
    end
 end
    
@@ -95,7 +121,9 @@ Textures = {
    make_count_texture = make_count_texture,
    make_solid_pigment = make_solid_pigment,
    make_checkered_pigment = make_checkered_pigment,
-   make_mandelbrot_pigment = make_mandelbrot_pigment
+   make_mandelbrot_pigment = make_mandelbrot_pigment,
+   map_rectangular = map_rectangular,
+   map_spherical = map_spherical
 }
 
 return Textures