-- 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
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)
local light_dir = (light-location)/light_dist
local vis = light_visibility(location + light_dir*eps, light_dir, eps, light_dist, 1, sdf)
+ -- local vis = 1.0
local Idiff = math.max(normal*light_dir, 0)
local Ispec = math.pow(math.max(light_dir*reflected_ray,0),shiny)
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)
+local function make_checkered_pigment(pigment1, pigment2)
+ 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
+ return pigment1(x,y)
else
- return colour2
+ return pigment2(x,y)
end
end
end
-local function make_mandelbrot_pigment()
+local function make_image_pigment(filename,scale)
+
+ print("Loading image pigmant from '" .. filename .. "'...")
+
+ local f = assert(io.open(filename, "rb"))
+ local data = f:read("*all")
+ f:close()
+
+ local start,_,wstr,hstr,dstr,raster =
+ string.find(data, "^P6[%s%c]+(%d+)[%s%c]+(%d+)[%s%c]+(%d+)[%s%c](.*)$")
+
+ if start ~= 1 then
+ error("Error reading image. Is it in PPM(P6) format?")
+ end
+
+ if dstr ~= "255" then
+ error("Only images with a depth of 255 are supported.")
+ end
+
+ local width = tonumber(wstr)
+ local height = tonumber(hstr)
+ local depth = tonumber(dstr)
+
+ local pixels = {}
+ local i = 1
+ for triple in string.gmatch(raster, "...") do
+ local _,_,r,g,b = string.find(triple, "(.)(.)(.)")
+ pixels[i] = {string.byte(r)/depth, string.byte(g)/depth, string.byte(b)/depth}
+ i = i + 1
+ end
+
+ print("done.")
+ print("(Read " .. tostring(#pixels) .. " pixels.)")
- local maxiter = 100
- local set_colour = {0,0,0}
+ local pixels_per_unit = math.max(width,height)
+
+ return function(x,y)
+ local xi = math.floor(((x+0.5)*pixels_per_unit/scale)%width) + 1
+ local yi = math.floor(((y+0.5)*pixels_per_unit/scale)%height) + 1
+ local i = width*(yi-1) + xi
+ if pixels[i] == nil then
+ error("Pixel not found at xi=" .. tostring(xi) .. " yi=" .. tostring(yi))
+ end
+ return pixels[i]
+ end
+end
+
+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,
cx, cy, iter-1)
end
-
- local xp = x^2 - y^2 + cx
- local yp = 2*x*y + cy
end
return function (x,y)
- get_col(0,0,x,y,maxiter)
+ 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
make_flat_texture = make_flat_texture,
make_count_texture = make_count_texture,
make_solid_pigment = make_solid_pigment,
- make_checkered_pigment = make_checkered_pigment
+ make_checkered_pigment = make_checkered_pigment,
+ make_image_pigment = make_image_pigment,
+ make_mandelbrot_pigment = make_mandelbrot_pigment,
+ map_rectangular = map_rectangular,
+ map_spherical = map_spherical
}
return Textures