-- Geometric primitives for raymarching
require "Vector"
local V = Vector

local function make_sphere(centre, radius, texture)
   local norm = V.norm
   return function(p)
      return {dist = V.norm(p-centre) - radius,
              texture = texture}
   end
end

local function make_plane(centre, normal, texture)
   return function(p)
      return {dist = normal*(p-centre),
              texture = texture}
   end
end

local function make_pipe(centre, radius, axis, texture)
   return function(p)
      return {dist = V.norm(V.cross(p-centre, axis)) - radius,
              texture = texture}
   end
end


Primitives = {
   make_sphere = make_sphere,
   make_plane = make_plane,
   make_pipe = make_pipe
}

return Primitives