-- LUA Script - precede every function and global member wit	h lowercase name of script + '_main'
local helicopter_rocket_assigned = {}
local helicopter_rocket_timer    = {}

local sin    = math.sin
local cos    = math.cos

function helicopter_rocket_init(e)
	CollisionOff(e)
end

function hrFire(e, quat)
	helicopter_rocket_assigned[e] = {fired = true, 
									 smoke = false, 
									 quat = quat} 
									 
	helicopter_rocket_timer[e] = 0
end

local Q = require "scriptbank\\quatlib"

local function Rotate3D (x, y, z, xrot, yrot, zrot) 

	function RotatePoint2D (x, y, Ang)  -- Ang in radians
		local Sa, Ca = sin(Ang), cos(Ang)
		return x*Ca - y*Sa, x*Sa + y*Ca
	end
 
	local NX, NY, NZ = x, y, z

	-- X
	NZ, NY = RotatePoint2D (NZ, NY, -xrot)
	
	-- Y
	NX, NZ = RotatePoint2D (NX, NZ, -yrot)
	
	-- Z
	NY, NX = RotatePoint2D (NY, NX, -zrot)

	return NX, NY, NZ
end

local function WillHitObject(sx,sy,sz,ex,ey,ez,ro)
	
	local obj = IntersectAll(sx, sy, sz, ex, ey, ez, ro)
	
	return obj and obj ~= 0
end

function helicopter_rocket_main(e)
	local timer = helicopter_rocket_timer[e]
	
	if timer == nil then
		helicopter_rocket_timer[e] = 0
		return
	end
	
	if g_Time > timer and HeliAddRocket ~= nil then
		if helicopter_rocket_assigned[e] == nil then
			if HeliAddRocket(e) then 
				helicopter_rocket_assigned[e] = {fired = false}
				timer = math.huge
			end
		end
		-- only try to assign rocket once per second
		timer = g_Time + 1000
	end
	
	local hr = helicopter_rocket_assigned[e]
	
	if hr == nil then return end
	
	if hr.fired then
		-- calculate new position
		local xA, yA, zA = Q.ToEuler(hr.quat)

		-- change the vector to match 'forward' for the model, i.e. pointing up is 0,0,1 left would be 1,0,0 etc
		local vX, vY, vZ = Rotate3D (0, 0, 1, xA, yA, zA)
		local Ent = g_Entity[e]
		
		local nX = Ent.x + vX * 50
		local nY = Ent.y + vY * 50
		local nZ = Ent.z + vZ * 50
		
		-- check collision with terrain or object
		if nY < GetTerrainHeight(nX, nZ) or
		   WillHitObject(Ent.x, Ent.y, Ent.z, nX, nY, nZ, Ent.obj) then
			SetEntityHealth(e, 0)
			hr.fired = false
			StopParticleEmitter(e)
			return
		end
		
		if not hr.smoke then
			StartParticleEmitter(e)
		end
		-- move rocket	
		ResetPosition(e, nX, nY, nZ)
	end
end