#!/usr/bin/env lua

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

-- This program that draws a scene multiple times from different camera angles
-- and positions.  The rasters are saved in the `frames' directory, and if
-- ffmpeg is installed, they will also be combined into a video file.  The
-- camera will make a full rotation along the X and Z axes, around a specified
-- point (center), all the while looking at some other point (look).
-- This must be called from the same directory where the rasterize program is.

local size      = {w = 640, h = 480}    -- width and height of the viewport
local frames    = 512                   -- number of animation frames

local look      = {x = 2, y = 1, z = 2} -- the point to look at
local center    = {x = 0, y = 1, z = 0} -- center of rotation
local distance  = 4                     -- the distance from the center
local start     = math.pi               -- where is the first frame

local jobs      = 6                     -- number of concurrent renderings

-- the actual objects of the scene that will be drawn:
local scene = [[
L 0 1000000 0 1 1 1 1 1 1
L 0 0 1000000 1 1 1 1 1 1
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 -2
s 1 1 1
g dragon.raw
c 0.7 0.3 0.2 0.8 0.2 0.1 0.9 0.2 0.2
t -2 -1 -2
s 2 2 2
g budda.raw
c 0.1 0.2 0.7 0.1 0.3 0.9 0.2 0.1 0.8
t 2 -1.5 2
s 10 10 10
g bunny.raw
c 0.9 0.8 0.9 0.8 0.7 0.9 0.9 0.8 0.7
t -2 -1 2
s 10 10 10
g teapot2.raw
c 0 1 0 0 1 0 0 1 0
t 0 -1 0
s 0.6 0.6 0.6
]]


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

local fmt   = string.format
local write = function(...) io.write(fmt(...)) end

function render(i, v)
    while i and v do
        local filename  = fmt("frames/anim%04d.bmp", i)
        local command   = fmt("./rasterize -o %s >/dev/null", filename)
        local out = io.popen(command, "w")
        write("\27[80D\27[2Kframe\t %4d / %d", i + 1, frames)
        out:write(fmt([[
U3
%d %d
%f %f %f
%f %f %f
0 1 0
1.57 %f 0.1 1000
%s
X
]], size.w, size.h, v.x, v.y, v.z, look.x, look.y, look.z, size.w/size.h, scene))
        i, v = coroutine.yield()
        out:close()
    end
end


print("Animating scene...")

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

os.execute("rm -rf frames && mkdir frames >/dev/null 2>&1")
for i = 0,(frames-1) do
    local t = start + 2 * math.pi * i / frames
    local v = {
        x = math.cos(t),
        y = 0,
        z = math.sin(t),
    }
    v = vec_add(vec_scale(v, distance), center)
    threads[1 + (i % jobs)](i, v)
end
for _,thread in ipairs(threads) do thread(null) end
print()

if os.execute("ffmpeg -i frames/anim%04d.bmp -b 1024k -y -an scene.avi") == 0 then
    print("Animation written to scene.avi.")
end