vecs.lua

-- some math stuff for speed
local _atan2=math.atan2
local _sqrt=math.sqrt
local _sin=math.sin
local _cos=math.cos
local _2pi=math.pi * 2
-- 2d vector 
local vec2 = {}
setmetatable(vec2, vec2);
vec2.type = vec2
function vec2:__call(x,y)
	local d={}
	vec2.__index=self
	setmetatable(d,self)
	d.x=x
	d.y=y
	return d
end
--	calc angle between two vec2's
function vec2:angTo(a)
	return (_atan2(a.x-self.x,a.y-self.y))
end
-- printable vec2
function vec2:__tostring()
	return string.format("(%f %f)",self.x,self.y)
end
-- make sure length is <1
function vec2:normalize()
	local w = _sqrt( self.x * self.x + self.y * self.y )
	self.x = self.x / w
	self.y = self.y / w
end

function vec2:dist(b)
  local dx = self.x - b.x
  local dy = self.y - b.y
  local s = dx * dx + dy * dy
  return _sqrt(s)
end
--	lerp between 2 angles
function angleLerp(a0,a1,t)
	da = (a1 - a0) % _2pi
	det = 2*da % _2pi - da
	return a0 + det*t
end
--	simple bullet
local bullets = {}
local bullet = {}
setmetatable(bullet, bullet)
bullet.type = bullet
function bullet:__call(x,y)
	local b={}
	bullet.__index=self
	setmetatable(b,self)
	b.pos = vec2(x,y)
	b.angle = math.random(0,360)
	b.speed = math.random(1,5)/5
	b.turnspeed=math.random(1,50)/1000
	table.insert(bullets,b)
	return b
end
--	the logic part 
function bullet:think()
	if (self.pos:dist(posb)<15) then 
		return false
	end
--	print(string.format("%0.2f",self.pos:dist(posb)),self.pos.x,self.pos.y,4)
	
	self.aim_angle = self.pos:angTo(posb)
	self.pos.x=self.pos.x + _sin(b.angle)*self.speed							
	self.pos.y=self.pos.y + _cos(b.angle)*self.speed							
	self.angle=angleLerp(b.angle,self.aim_angle,self.turnspeed)
	return true
end
-- drawing
function bullet:draw()
	circb(b.pos.x,b.pos.y,4,14)
	line(b.pos.x,b.pos.y,
		b.pos.x+_sin(b.aim_angle)*15,
		b.pos.y+_cos(b.aim_angle)*15,
		6)
	line(b.pos.x,b.pos.y,
		b.pos.x+_sin(b.angle)*15,
		b.pos.y+_cos(b.angle)*15,
		8)
end

posa=vec2(32,32)
posb=vec2(64,64)

function TIC()
	cls(0)
	posa.x,posa.y,b = mouse()
	if b~=lb then 
		bullet(posa.x,posa.y)
		lb=b
	end
	for i=#bullets,1,-1 do
		b=bullets[i]
		if (b:think()==false) then 
			table.remove(bullets,i)		
		end
		b:draw()
	end
--	draw the "hero" mouse
	circ(posa.x,posa.y,4,14)
-- draw the target
	circb(posb.x,posb.y,15,2)
	posb.x=120+_sin(time()/1000)*120
	posb.y=68+_cos(time()/1200)*68
end