1 -- Textures for raymarcher
9 local function make_phong_texture(lights, mapped_pigment, amb, diff, spec, shiny)
10 local normalize = V.normalize
13 local function light_visibility(location, light_dir, pos, dest, res, sdf)
14 local p = sdf(location)
15 if pos + p.dist > dest then
17 elseif p.dist < eps then
20 return light_visibility(location + light_dir*p.dist, light_dir, pos+p.dist,
21 dest, math.min(res, 30*p.dist/(pos+p.dist)), sdf)
25 return function (location, ray_dir, normal, count, sdf)
26 local colour = mapped_pigment(location)
27 local thiscol = {colour[1]*amb, colour[2]*amb, colour[3]*amb}
29 local reflected_ray = ray_dir - normal*(ray_dir*normal*2)
30 for _,light in ipairs(lights) do
31 local light_dist = V.norm(light-location)
32 local light_dir = (light-location)/light_dist
34 local vis = light_visibility(location + light_dir*eps, light_dir, eps, light_dist, 1, sdf)
37 local Idiff = math.max(normal*light_dir, 0)
38 local Ispec = math.pow(math.max(light_dir*reflected_ray,0),shiny)
40 thiscol[1] = thiscol[1] + vis*(colour[1]*Idiff*diff + Ispec*spec)
41 thiscol[2] = thiscol[2] + vis*(colour[2]*Idiff*diff + Ispec*spec)
42 thiscol[3] = thiscol[3] + vis*(colour[3]*Idiff*diff + Ispec*spec)
49 local function make_count_texture(scale)
50 return function (location, ray_dir, normal, count, sdf)
51 return {count*scale, count*scale, count*scale}
55 local function make_flat_texture(mapped_pigment)
56 return function (location, ray_dir, normal, count, sdf)
57 return mapped_pigment(location)
64 local function make_solid_pigment(colour)
70 local function make_checkered_pigment(pigment1, pigment2)
72 if (x%1 < 0.5 and y%1 < 0.5) or (x%1 > 0.5 and y%1 > 0.5) then
80 local function make_image_pigment(filename,scale)
82 print("Loading image pigmant from '" .. filename .. "'...")
84 local f = assert(io.open(filename, "rb"))
85 local data = f:read("*all")
88 local start,_,wstr,hstr,dstr,raster =
89 string.find(data, "^P6[%s%c]+(%d+)[%s%c]+(%d+)[%s%c]+(%d+)[%s%c](.*)$")
92 error("Error reading image. Is it in PPM(P6) format?")
96 error("Only images with a depth of 255 are supported.")
99 local width = tonumber(wstr)
100 local height = tonumber(hstr)
101 local depth = tonumber(dstr)
105 for triple in string.gmatch(raster, "...") do
106 local _,_,r,g,b = string.find(triple, "(.)(.)(.)")
107 pixels[i] = {string.byte(r)/depth, string.byte(g)/depth, string.byte(b)/depth}
112 print("(Read " .. tostring(#pixels) .. " pixels.)")
114 local pixels_per_unit = math.max(width,height)
117 local xi = math.floor(((x+0.5)*pixels_per_unit/scale)%width) + 1
118 local yi = math.floor(((y+0.5)*pixels_per_unit/scale)%height) + 1
119 local i = width*(yi-1) + xi
120 if pixels[i] == nil then
121 error("Pixel not found at xi=" .. tostring(xi) .. " yi=" .. tostring(yi))
127 local function make_mandelbrot_pigment(set_pigment, nonset_pigment, max_iter)
129 local function get_col(x,y,cx,cy,iter)
131 return set_pigment(cx, cy)
132 elseif x^2 + y^2 > 4 then
133 return nonset_pigment(cx, cy)
135 return get_col(x^2 - y^2 + cx,
141 return function (x,y)
142 return get_col(0,0,x,y,max_iter)
146 local function make_rainbow_pigment(scale)
147 return function (x,y)
149 local Ired = math.sin(x/math.pi/scale)^2 * math.sin(y/math.pi/scale)^2
150 local Igreen = math.cos(x/math.pi/scale)^2 * math.sin(y/math.pi/scale)^2
151 local Iblue = math.sin(x/math.pi/scale)^2 * math.cos(y/math.pi/scale)^2
153 return C.red*Ired + C.green*Igreen + C.blue*Iblue
160 -- These functions define mappings from 3D world coordinates to 2D
161 -- texture/pigment coordinates
163 local function map_rectangular(pigment, xvec, yvec)
164 return function(location)
165 return pigment(location*xvec, location*yvec)
169 local function map_spherical(pigment, centre, scale_theta, scale_phi)
170 return function(location)
171 local r = location-centre
172 local rnorm = V.norm(r)
174 local phi = math.acos((V.z*r)/rnorm)
175 local theta = math.acos((V.x*r)/V.norm(V.cross(V.z,r)))
177 return pigment(theta*scale_theta/math.pi, phi*scale_phi/math.pi)
182 make_phong_texture = make_phong_texture,
183 make_flat_texture = make_flat_texture,
184 make_count_texture = make_count_texture,
185 make_solid_pigment = make_solid_pigment,
186 make_checkered_pigment = make_checkered_pigment,
187 make_image_pigment = make_image_pigment,
188 make_rainbow_pigment = make_rainbow_pigment,
189 make_mandelbrot_pigment = make_mandelbrot_pigment,
190 map_rectangular = map_rectangular,
191 map_spherical = map_spherical