From 8a7513e67adf4076d7c256976c4a86fa936ff1a6 Mon Sep 17 00:00:00 2001
From: ubq323 <ubq323@ubq323.website>
Date: Sun, 2 Nov 2025 20:14:06 +0000
Subject: pos: add __unm round rot sproj proj angle, inline arithmetic, and
 make norm of 0 be 0

---
 pos.lua | 24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

(limited to 'pos.lua')

diff --git a/pos.lua b/pos.lua
index 18d559b..ba1a404 100644
--- a/pos.lua
+++ b/pos.lua
@@ -1,4 +1,5 @@
 local class = require'r.class'
+local rmath = require'r.math'
 
 local Pos = class()
 function Pos.new(cls)
@@ -18,6 +19,7 @@ end
 function Pos.__sub(self,other)
 	return Pos:make(self.x-other.x,self.y-other.y)
 end
+function Pos.__unm(self) return Pos(-self.x,-self.y)  end
 function Pos.__mul(a,b)
 	if type(a) == "number" then
 		return Pos:make(a*b.x,a*b.y)
@@ -35,13 +37,16 @@ end
 function Pos.__eq(a,b) return a.x==b.x and a.y==b.y end
 function Pos.lensq(self) return self.x^2 + self.y^2 end
 function Pos.len(self) return math.sqrt(self:lensq()) end
-function Pos.norm(self) return self/self:len() end
+function Pos.norm(self)
+	local l = self:len()
+	if l < 0.00001 then return Pos(0,0) else return self/l end end
 function Pos.l1(self) return math.abs(self.x) + math.abs(self.y) end
 function Pos.linf(self) return math.max(math.abs(self.x),math.abs(self.y)) end
 function Pos.dot(self,other) return self.x*other.x+self.y*other.y end
 function Pos.vals(self) return self.x, self.y end
 function Pos.floor(self) return Pos:make(math.floor(self.x),math.floor(self.y)) end
 function Pos.ceil(self) return Pos:make(math.ceil(self.x),math.ceil(self.y)) end
+function Pos.round(self) return Pos:make(rmath.round(self.x),rmath.round(self.y)) end
 function Pos.divmod(self,size) local div = (self/size):floor() return div, self-div*size end
 function Pos.__tostring(self)
 	return string.format("(%.2f,%.2f)",self.x,self.y)
@@ -50,7 +55,24 @@ function Pos.key(self) return self.x .. ':' .. self.y end
 function Pos.unkey(cls,k)
 	local a,b = k:match"(%-?%d+):(%-?%d+)"
 	return Pos(tonumber(a),tonumber(b)) end
+function Pos.rot(self,a)
+	local c,s = math.cos(a),math.sin(a)
+	-- [ C, -S ]
+	-- [ S,  C ] 
+	return Pos(self.x*c - self.y*s, self.x*s + self.y*c) end
+function Pos.sproj(self,b) return self:dot(b:norm()) end
+function Pos.proj(self,b) return self:sproj(b)*b:norm() end
+function Pos.angle(self) return (math.atan2 or math.atan)(self.y,self.x) end
+
+-- inplace arithmetic
+function Pos.addby (self,by) self.x=self.x+by.x  self.y=self.y+by.y end
+function Pos.addbyv(self,x,y)self.x=self.x+x     self.y=self.y+y    end
+function Pos.subby (self,by) self.x=self.x-by.x  self.y=self.y-by.y end
+function Pos.subbyv(self,x,y)self.x=self.x-x     self.y=self.y-y    end
+function Pos.mulby (self,by) self.x=self.x*by    self.y=self.y*by   end
+function Pos.divby (self,by) self.x=self.x/by    self.y=self.y/by   end
 
 return Pos
 
 
+
-- 
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