1 -- Textures for raymarcher
6 local function make_phong_texture(lights, mapped_pigment, amb, diff, spec, shiny)
7 local normalize = V.normalize
10 local function light_visibility(location, light_dir, pos, dest, res, sdf)
11 local p = sdf(location)
12 if pos + p.dist > dest then
14 elseif p.dist < eps then
17 return light_visibility(location + light_dir*p.dist, light_dir, pos+p.dist,
18 dest, math.min(res, 30*p.dist/(pos+p.dist)), sdf)
22 return function (location, ray_dir, normal, count, sdf)
23 local colour = mapped_pigment(location)
24 local thiscol = {colour[1]*amb, colour[2]*amb, colour[3]*amb}
26 local reflected_ray = ray_dir - normal*(ray_dir*normal*2)
27 for _,light in ipairs(lights) do
28 local light_dist = V.norm(light-location)
29 local light_dir = (light-location)/light_dist
31 local vis = light_visibility(location + light_dir*eps, light_dir, eps, light_dist, 1, sdf)
33 local Idiff = math.max(normal*light_dir, 0)
34 local Ispec = math.pow(math.max(light_dir*reflected_ray,0),shiny)
36 thiscol[1] = thiscol[1] + vis*(colour[1]*Idiff*diff + Ispec*spec)
37 thiscol[2] = thiscol[2] + vis*(colour[2]*Idiff*diff + Ispec*spec)
38 thiscol[3] = thiscol[3] + vis*(colour[3]*Idiff*diff + Ispec*spec)
45 local function make_count_texture(scale)
46 return function (location, ray_dir, normal, count, sdf)
47 return {count*scale, count*scale, count*scale}
51 local function make_flat_texture(mapped_pigment)
52 return function (location, ray_dir, normal, count, sdf)
53 return mapped_pigment(location)
60 local function make_solid_pigment(colour)
66 local function make_checkered_pigment(colour1, colour2)
68 if (x%1 < 0.5 and y%1 < 0.5) or (x%1 > 0.5 and y%1 > 0.5) then
76 local function make_mandelbrot_pigment(set_pigment, nonset_pigment, max_iter)
78 local function get_col(x,y,cx,cy,iter)
80 return set_pigment(cx, cy)
81 elseif x^2 + y^2 > 4 then
82 return nonset_pigment(cx, cy)
84 return get_col(x^2 - y^2 + cx,
91 return get_col(0,0,x,y,max_iter)
97 -- These functions define mappings from 3D world coordinates to 2D
98 -- texture/pigment coordinates
100 local function map_rectangular(pigment, xvec, yvec)
101 return function(location)
102 return pigment(location*xvec, location*yvec)
106 local function map_spherical(pigment, centre, scale_theta, scale_phi)
107 return function(location)
108 local r = location-centre
109 local rnorm = V.norm(r)
111 local phi = math.acos((V.z*r)/rnorm)
112 local theta = math.acos((V.x*r)/V.norm(V.cross(V.z,r)))
114 return pigment(theta*scale_theta/math.pi, phi*scale_phi/math.pi)
119 make_phong_texture = make_phong_texture,
120 make_flat_texture = make_flat_texture,
121 make_count_texture = make_count_texture,
122 make_solid_pigment = make_solid_pigment,
123 make_checkered_pigment = make_checkered_pigment,
124 make_mandelbrot_pigment = make_mandelbrot_pigment,
125 map_rectangular = map_rectangular,
126 map_spherical = map_spherical