-- Textures for raymarcher
+
require "Vector"
local V = Vector
-local function make_phong(lights, colour, amb, spec, shiny)
- return function (location, ray_dir, normal, count)
- local thiscol = {0, 0, 0}
- local reflected_ray = V.normalize(normal*(ray_dir*normal*2) - ray_dir)
+local function make_phong_texture(lights, mapped_pigment, amb, diff, spec, shiny)
+ local normalize = V.normalize
+
+ local eps = 0.0001
+ local function light_visibility(location, light_dir, pos, dest, res, sdf)
+ local p = sdf(location)
+ if pos + p.dist > dest then
+ return res
+ elseif p.dist < eps then
+ return 0.0
+ else
+ return light_visibility(location + light_dir*p.dist, light_dir, pos+p.dist,
+ dest, math.min(res, 30*p.dist/(pos+p.dist)), sdf)
+ end
+ end
+
+ return function (location, ray_dir, normal, count, sdf)
+ 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)
for _,light in ipairs(lights) do
- local light_dir = V.normalize(light-location)
- local Iamb = math.max(normal*light_dir, 0)
+ local light_dist = V.norm(light-location)
+ local light_dir = (light-location)/light_dist
+
+ local vis = light_visibility(location + light_dir*eps, light_dir, eps, light_dist, 1, sdf)
+
+ local Idiff = math.max(normal*light_dir, 0)
local Ispec = math.pow(math.max(light_dir*reflected_ray,0),shiny)
- thiscol[1] = thiscol[1] + colour[1]*Iamb*amb + Ispec*spec
- thiscol[2] = thiscol[2] + colour[2]*Iamb*amb + Ispec*spec
- thiscol[3] = thiscol[3] + colour[3]*Iamb*amb + Ispec*spec
+ thiscol[1] = thiscol[1] + vis*(colour[1]*Idiff*diff + Ispec*spec)
+ thiscol[2] = thiscol[2] + vis*(colour[2]*Idiff*diff + Ispec*spec)
+ thiscol[3] = thiscol[3] + vis*(colour[3]*Idiff*diff + Ispec*spec)
end
return thiscol
end
end
-local function make_count_texture()
- return function (location, ray_dir, normal, count)
- return {count/10, count/10, count/10}
+local function make_count_texture(scale)
+ return function (location, ray_dir, normal, count, sdf)
+ return {count*scale, count*scale, count*scale}
+ end
+end
+
+local function make_flat_texture(mapped_pigment)
+ return function (location, ray_dir, normal, count, sdf)
+ return mapped_pigment(location)
end
end
+
+-- Pigments
+
+local function make_solid_pigment(colour)
+ return function(x,y)
+ return colour
+ end
+end
+
+local function make_checkered_pigment(colour1, colour2)
+ 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
+ return colour2
+ end
+ 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_pigment(cx, cy)
+ elseif x^2 + y^2 > 4 then
+ return nonset_pigment(cx, cy)
+ else
+ return get_col(x^2 - y^2 + cx,
+ 2*x*y + cy,
+ cx, cy, iter-1)
+ end
+ end
+
+ return function (x,y)
+ 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
Textures = {
- make_phong = make_phong,
- make_count_texture = make_count_texture
+ make_phong_texture = make_phong_texture,
+ 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_mandelbrot_pigment = make_mandelbrot_pigment,
+ map_rectangular = map_rectangular,
+ map_spherical = map_spherical
}
return Textures