vector_extras/init.lua

local r_corr = 0.25 --remove a bit more nodes (if shooting diagonal) to let it look like a hole (sth like antialiasing)

-- this doesn't need to be calculated every time
local f_1 = 0.5-r_corr
local f_2 = 0.5+r_corr

--returns information about the direction
local function get_used_dir(dir)
	local abs_dir = {x=math.abs(dir.x), y=math.abs(dir.y), z=math.abs(dir.z)}
	local dir_max = math.max(abs_dir.x, abs_dir.y, abs_dir.z)
	if dir_max == abs_dir.x then
		local tab = {"x", {x=1, y=dir.y/dir.x, z=dir.z/dir.x}}
		if dir.x >= 0 then
			tab[3] = "+"
		end
		return tab
	end
	if dir_max == abs_dir.y then
		local tab = {"y", {x=dir.x/dir.y, y=1, z=dir.z/dir.y}}
		if dir.y >= 0 then
			tab[3] = "+"
		end
		return tab
	end
	local tab = {"z", {x=dir.x/dir.z, y=dir.y/dir.z, z=1}}
	if dir.z >= 0 then
		tab[3] = "+"
	end
	return tab
end

local function node_tab(z, d)
	local n1 = math.floor(z*d+f_1)
	local n2 = math.floor(z*d+f_2)
	if n1 == n2 then
		return {n1}
	end
	return {n1, n2}
end

local function return_line(pos, dir, range) --range ~= length
	local tab = {}
	local num = 1
	local t_dir = get_used_dir(dir)
	local dir_typ = t_dir[1]
	if t_dir[3] == "+" then
		f_tab = {0, range, 1}
	else
		f_tab = {0, -range, -1}
	end
	local d_ch = t_dir[2]
	if dir_typ == "x" then
		for d = f_tab[1],f_tab[2],f_tab[3] do
			local x = d
			local ytab = node_tab(d_ch.y, d)
			local ztab = node_tab(d_ch.z, d)
			for _,y in ipairs(ytab) do
				for _,z in ipairs(ztab) do
					tab[num] = {x=pos.x+x, y=pos.y+y, z=pos.z+z}
					num = num+1
				end
			end
		end
	elseif dir_typ == "y" then
		for d = f_tab[1],f_tab[2],f_tab[3] do
			local xtab = node_tab(d_ch.x, d)
			local y = d
			local ztab = node_tab(d_ch.z, d)
			for _,x in ipairs(xtab) do
				for _,z in ipairs(ztab) do
					tab[num] = {x=pos.x+x, y=pos.y+y, z=pos.z+z}
					num = num+1
				end
			end
		end
	else
		for d = f_tab[1],f_tab[2],f_tab[3] do
			local xtab = node_tab(d_ch.x, d)
			local ytab = node_tab(d_ch.y, d)
			local z = d
			for _,x in ipairs(xtab) do
				for _,y in ipairs(ytab) do
					tab[num] = {x=pos.x+x, y=pos.y+y, z=pos.z+z}
					num = num+1
				end
			end
		end
	end
	return tab
end

local function table_contains2(t, v)
	for i = #t, 1, -1 do
		if t[i] == v then
			return true
		end
	end
	return false
end

local function return_fine_line(pos, dir, range, scale)
	local ps1 = return_line(vector.round(vector.multiply(pos, scale)), dir, range*scale)
	local ps2 = {}
	local ps2_num = 1
	for _,p1 in ipairs(ps1) do
		local p2 = vector.round(vector.divide(p1, scale))
		if not table_contains2(ps2, p2) then
			ps2[ps2_num] = p2
			ps2_num = ps2_num+1
		end
	end
	return ps2
end

function vector.fine_line(pos, dir, range, scale)
	--assert_vector(pos)
	if not range then --dir = pos2
		dir = vector.direction(pos, dir)
		range = vector.distance(pos, dir)
	end
	return return_fine_line(pos, dir, range, scale)
end

function vector.line(pos, dir, range)
	--assert_vector(pos)
	if not range then --dir = pos2
		dir = vector.direction(pos, dir)
		range = vector.distance(pos, dir)
	end
	return return_line(pos, dir, range)
end

function vector.straightdelay(s, v, a)
	if not a then
		return s/v
	end
	return (math.sqrt(v*v+2*a*s)-v)/a
end

-- needs to get reworked
function vector.sun_dir(t)
	if t < 0.25
	or t > 0.75 then
		return
	end
	local p2
	if t > 0.5 then
		p2 = {x=-4, y=1/(2*t-1), z=0}
	else
		p2 = {x=4, y=1/(1-2*t), z=0}
	end	
	return vector.direction({x=0,y=0,z=0}, p2)
end

function vector.inside(pos, minp, maxp)
	for _,i in ipairs({"x", "y", "z"}) do
		if pos[i] < minp[i]
		or pos[i] > maxp[i] then
			return false
		end
	end
	return true
end

function vector.minmax(p1, p2)
	local p1 = vector.new(p1) --Are these 2 redefinitions necessary?
	local p2 = vector.new(p2)
	for _,i in ipairs({"x", "y", "z"}) do
		if p1[i] > p2[i] then
			p1[i], p2[i] = p2[i], p1[i]
		end
	end
	return p1, p2
end

function vector.move(p1, p2, s)
	return vector.round(
		vector.add(
			vector.multiply(
				vector.direction(
					p1,
					p2
				),
				s
			),
			p1
		)
	)
end

local explosion_tables = {}
function vector.explosion_table(r)
	local table = explosion_tables[r]
	if table then
		return table
	end

	local t1 = os.clock()
	local tab, n = {}, 1

	local tmp = r*r + r
	for x=-r,r do
		for y=-r,r do
			for z=-r,r do
				local rc = x*x+y*y+z*z 
				if rc <= tmp then
					local np={x=x, y=y, z=z}
					if math.floor(math.sqrt(rc) +0.5) > r-1 then
						tab[n] = {np, true}
					else
						tab[n] = {np}
					end
					n = n+1
				end
			end
		end
	end
	explosion_tables[r] = tab
	print(string.format("[vector_extras] table created after ca. %.2fs", os.clock() - t1))
	return tab
end

local circle_tables = {}
function vector.circle(r)
	local table = circle_tables[r]
	if table then
		return table
	end

	local t1 = os.clock()
	local tab, n = {}, 1

	for i = -r, r do
		for j = -r, r do
			if math.floor(math.sqrt(i*i+j*j)+0.5) == r then
				tab[n] = {x=i, y=0, z=j}
				n = n+1
			end
		end
	end
	circle_tables[r] = tab
	print(string.format("[vector_extras] table created after ca. %.2fs", os.clock() - t1))
	return tab
end

local ring_tables = {}
function vector.ring(r)
	local table = ring_tables[r]
	if table then
		return table
	end

	local t1 = os.clock()
	local tab, n = {}, 1

	local tmp = r*r
	local p = {x=math.floor(r+0.5), z=0}
	while p.x > 0 do
		tab[n] = p
		n = n+1
		local p1, p2 = {x=p.x-1, z=p.z}, {x=p.x, z=p.z+1}
		local dif1 = math.abs(tmp-p1.x*p1.x-p1.z*p1.z)
		local dif2 = math.abs(tmp-p2.x*p2.x-p2.z*p2.z)
		if dif1 <= dif2 then
			p = p1
		else
			p = p2
		end
	end

	local tab2, n = {}, 1
	for _,i in ipairs(tab) do
		for _,j in ipairs({
			{i.x, i.z},
			{-i.z, i.x},
			{-i.x, -i.z},
			{i.z, -i.x},
		}) do
			tab2[n] = {x=j[1], y=0, z=j[2]}
			n = n+1
		end
	end
	ring_tables[r] = tab2
	print(string.format("[vector_extras] table created after ca. %.2fs", os.clock() - t1))
	return tab2
end