Converted VectorTest into project

main.lua

@@ -0,0 +1,170 @@
+ball_count = 16
+ball_radius = 5
+
+function _init()
+	balls = {}
+	collisions = {}
+	for i=1,ball_count do
+		add(balls, ball:new({
+			pos=vec2:new(rnd(127),rnd(127)),
+			vel=vec2:new(rnd(2)-1,rnd(2)-1):normal(),
+			col=rnd(15)+1
+		}))
+	end
+end
+
+function _update60()
+	for b in all(balls) do
+		b:move()
+		b:edge_bounce()
+	end
+	for b in all(balls) do
+	 b:check_collisions(balls)
+	end 
+	handle_collisions(balls)
+	collisions = {}
+end	
+
+function _draw()
+	cls()
+	for b in all(balls) do
+		b:draw()
+	end
+end
+
+function handle_collisions()
+	for source,colls in pairs(collisions) do
+		for target,diff in pairs(colls) do
+  	local n = diff:normal()
+ 	 local steps = 0
+ 	 local rewind = 0
+ 	 local s_xpoint = source.pos
+ 	 local t_xpoint = target.pos
+ 	 repeat
+ 			steps += 1
+ 			rewind += 0.1 * steps
+ 			s_xpoint = source.pos - source.vel * rewind
+ 			t_xpoint = target.pos - target.vel * rewind
+ 		until (s_xpoint - t_xpoint):mag() >= source.rad + target.rad					
+ 		source.vel = collision_vel(s_xpoint, source.vel, t_xpoint, target.vel)
+ 		target.vel = collision_vel(t_xpoint, target.vel, s_xpoint, source.vel)
+ 		source.pos = s_xpoint + source.vel * rewind
+ 		target.pos = t_xpoint + target.vel * rewind 
+		end
+	end
+end				
+
+vec2 = {
+	x = 0,
+	y = 0,
+	
+	mag = function(self)
+	 return sqrt(self.x^2+self.y^2)
+	end,
+	
+	dot = function(self,v)
+		return self.x * v.x + self.y * v.y
+	end,
+	
+	normal	= function(self)
+		local mag = self:mag()
+		return vec2:new(self.x/mag, self.y/mag)
+	end,
+	
+	bounce = function(self, n, b)
+		local b = b or 1
+		local n = n:normal()
+		return (n * -2 * self:dot(n) + self) * b
+	end
+}
+
+vec2.__eq = function(v1,v2) return v1.x == v2.x and v1.y == v2.y end
+vec2.__add = function(v1,v2) return vec2:new(v1.x+v2.x,v1.y+v2.y) end
+vec2.__sub = function(v1,v2) return vec2:new(v1.x-v2.x,v1.y-v2.y) end
+vec2.__mul = function(v,s) return vec2:new(v.x*s,v.y*s) end
+vec2.__div = function(v,s) return vec2:new(v.x/s,v.y/s) end
+vec2.__unm = function(v) return vec2:new(-v.x,-v.y) end
+vec2.__tostring = function(v) return "{x: "..v.x..",y: "..v.y.."}" end
+vec2.__index = vec2
+
+function vec2:new(x,y)
+	local x = x or 0
+	local y = y or 0
+	local o = {x=x,y=y}
+	setmetatable(o, self)
+	o.__index = self
+	return o
+end
+
+function vec2:print_debug(v)
+	local v = v or vec2:new(0,1)
+	print("vec: "..vec2.__tostring(self))
+	print("mag: "..self:mag())
+	print("dot: "..self:dot(v))
+	print("normal: "..vec2.__tostring(self:normal()))
+	print("bounce: "..vec2.__tostring(self:bounce(v)))
+	print("inv: "..vec2.__tostring(-self))
+end
+
+ball = {
+	__count = 0,
+	id = nil,
+	pos = vec2:new(0,0),
+	vel = vec2:new(0,0),
+	rad = ball_radius,
+	col = 7,
+	
+	draw = function(self)
+		circfill(self.pos.x, self.pos.y, self.rad, self.col)
+	end,
+	
+	move = function(self)
+		self.pos += self.vel
+	end,
+	
+	edge_bounce = function(self)
+		edge_normal = vec2:new()
+		for axis in all({"x","y"}) do
+			val = self.pos[axis]
+			if (val - self.rad < 0) then
+				self.pos[axis] = self.rad
+				edge_normal[axis] = 1
+			elseif (val + self.rad > 127) then
+				self.pos[axis] = 127 - self.rad
+				edge_normal[axis] = -1
+			end 
+		end
+		if (edge_normal.x != 0 or edge_normal.y != 0) then
+			self.vel = self.vel:bounce(edge_normal)
+		end
+	end,
+	
+	check_collisions = function(self, balls)
+		for b in all(balls) do
+			if (b.id != self.id and (collisions[b] == nil or collisions[b][self] == nil)) then
+				local diff = self.pos - b.pos
+				if ((diff):mag() < self.rad + b.rad) then
+				 collisions[self] = collisions[self] or {}
+				 collisions[self][b] = diff
+				end
+			end
+		end
+	end,
+}
+ball.__index = ball
+
+function ball:new(o)
+	ball.__count += 1
+	local o = o or {}
+	o.id = ball.__count
+	o.col = o.id % 16
+	setmetatable(o, self)
+	o.__index = self
+	return o
+end
+
+function collision_vel(x1,v1,x2,v2)
+		local x_diff = x1 - x2
+		local v_diff = v1 - v2
+		return v1 - x_diff * v_diff:dot(x_diff) / x_diff:mag()^2
+end