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(pigment1, pigment2)
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_image_pigment(filename,scale)
78 print("Loading image pigmant from '" .. filename .. "'...")
80 local f = assert(io.open(filename, "rb"))
81 local data = f:read("*all")
84 local start,_,wstr,hstr,dstr,raster =
85 string.find(data, "^P6[%s%c]+(%d+)[%s%c]+(%d+)[%s%c]+(%d+)[%s%c](.*)$")
88 error("Error reading image. Is it in PPM(P6) format?")
92 error("Only images with a depth of 255 are supported.")
95 local width = tonumber(wstr)
96 local height = tonumber(hstr)
97 local depth = tonumber(dstr)
101 for triple in string.gmatch(raster, "...") do
102 local _,_,r,g,b = string.find(triple, "(.)(.)(.)")
103 pixels[i] = {string.byte(r)/depth, string.byte(g)/depth, string.byte(b)/depth}
108 print("(Read " .. tostring(#pixels) .. " pixels.)")
110 local pixels_per_unit = math.max(width,height)
113 local xi = math.floor(((x+0.5)*pixels_per_unit/scale)%width) + 1
114 local yi = math.floor(((y+0.5)*pixels_per_unit/scale)%height) + 1
115 local i = width*(yi-1) + xi
116 if pixels[i] == nil then
117 error("Pixel not found at xi=" .. tostring(xi) .. " yi=" .. tostring(yi))
123 local function make_mandelbrot_pigment(set_pigment, nonset_pigment, max_iter)
125 local function get_col(x,y,cx,cy,iter)
127 return set_pigment(cx, cy)
128 elseif x^2 + y^2 > 4 then
129 return nonset_pigment(cx, cy)
131 return get_col(x^2 - y^2 + cx,
137 return function (x,y)
138 return get_col(0,0,x,y,max_iter)
144 -- These functions define mappings from 3D world coordinates to 2D
145 -- texture/pigment coordinates
147 local function map_rectangular(pigment, xvec, yvec)
148 return function(location)
149 return pigment(location*xvec, location*yvec)
153 local function map_spherical(pigment, centre, scale_theta, scale_phi)
154 return function(location)
155 local r = location-centre
156 local rnorm = V.norm(r)
158 local phi = math.acos((V.z*r)/rnorm)
159 local theta = math.acos((V.x*r)/V.norm(V.cross(V.z,r)))
161 return pigment(theta*scale_theta/math.pi, phi*scale_phi/math.pi)
166 make_phong_texture = make_phong_texture,
167 make_flat_texture = make_flat_texture,
168 make_count_texture = make_count_texture,
169 make_solid_pigment = make_solid_pigment,
170 make_checkered_pigment = make_checkered_pigment,
171 make_image_pigment = make_image_pigment,
172 make_mandelbrot_pigment = make_mandelbrot_pigment,
173 map_rectangular = map_rectangular,
174 map_spherical = map_spherical