#!/usr/bin/env lua

--
-- CS5600 University of Utah
-- Charles McGarvey
-- mcgarvey@eng.utah.edu
--

-- Render a scene multiple times from different angles, like a camera
-- rotating around the object of a scene.

local size = {w = 640, h = 480}
local slices = 512

local center = {x = 0, y = 1, z = 0}
local look = {x = -2, y = -1, z = -2}
local distance = 4
local start = math.pi

local scene = [[
g teapot2.raw
c 1.0 1.0 0.0 1.0 1.0 0.0 1.0 1.0 0.0
t 0.0 0.0 0.0
s 0.6 0.6 0.6
g triangle.raw
c 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1
t 2.0 0.0 -2.0
s 1.0 1.0 1.0
g dragon.raw
c 0.7 0.3 0.2 0.8 0.2 0.1 0.9 0.2 0.2
t -2.0 -1.0 -2.0
s 2.0 2.0 2.0
g budda.raw
c 0.1 0.2 0.7 0.1 0.3 0.9 0.2 0.1 0.8
t 2.0 -1.5 2.0
s 10.0 10.0 10.0
g bunny.raw
c 0.9 0.8 0.9 0.8 0.7 0.9 0.9 0.8 0.7
t -2.0 -1.0 2.0
s 10.0 10.0 10.0
]]

function vec_add(a, b)
    return {x = a.x + b.x, y = a.y + b.y, z = a.z + b.z}
end

function vec_scale(v, s)
    return {x = v.x * s, y = v.y * s, z = v.z * s}
end

function render(i, v)
    while true do
        local out = io.popen("./project2 -", "w")
        out:write(string.format([[
U3
%d %d
%f %f %f
%f %f %f
0.0 1.0 0.0
1.57 %f 0.1 1000.0
%s
]], size.w, size.h, v.x, v.y, v.z, look.x, look.y, look.z, size.w/size.h, scene))
        local a, b = coroutine.yield()
        out:close()
        os.rename("stdin.bmp", string.format("anim%04d.bmp", i))
        if a == null then
            break
        else
            i = a
            v = b
        end
    end
end

local threads = {}
local jobs = 3
for i = 1,jobs do
    table.insert(threads, coroutine.wrap(render))
end

for i = 0,(slices-1) do
    local t = start + 2 * i * math.pi / slices
    local v = {
        x = math.cos(t),
        y = 0,
        z = math.sin(t),
    }
    v = vec_add(vec_scale(v, distance), center)
    threads[(i % jobs) + 1](i, v)
end

for k,v in ipairs(threads) do
    v(null)     -- clear up any leftover work
end