From a26131ab6e12da171829e360867bdf9de280fbea Mon Sep 17 00:00:00 2001
From: neviyn <neviynhd@gmail.com>
Date: Tue, 21 Jul 2020 14:32:09 +0100
Subject: [PATCH] Better float comparisons

---
 src/tuple.nim | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/src/tuple.nim b/src/tuple.nim
index f5ff582..edeac61 100644
--- a/src/tuple.nim
+++ b/src/tuple.nim
@@ -1,9 +1,17 @@
 from math import sqrt
 
+const
+    eps = 1.0e-7 ## Epsilon used for float comparisons.
+
+proc `=~` *(x, y: float): bool =
+    result = abs(x - y) < eps
+
 type
     Tuple4* = object
         x*, y*, z*, w*: float
 
+proc `==`*(lhs, rhs: Tuple4): bool = lhs.x =~ rhs.x and lhs.y =~ rhs.y and lhs.z =~ rhs.z and lhs.w =~ rhs.w
+
 proc point*(x: float, y: float, z: float): Tuple4 = Tuple4(x: x, y: y, z: z, w: 1)
 
 proc vector*(x: float, y: float, z: float): Tuple4 = Tuple4(x: x, y: y, z: z, w: 0)
@@ -11,8 +19,8 @@ proc vector*(x: float, y: float, z: float): Tuple4 = Tuple4(x: x, y: y, z: z, w:
 proc isPoint*(target: Tuple4): bool = target.w == 1
 proc isVector*(target: Tuple4): bool = target.w == 0
 
-proc `+`*(lhs: Tuple4, rhs: Tuple4): Tuple4 = Tuple4(x: lhs.x + rhs.x, y: lhs.y + rhs.y, z: lhs.z + rhs.z, w: lhs.w + rhs.w)
-proc `-`*(lhs: Tuple4, rhs: Tuple4): Tuple4 = Tuple4(x: lhs.x - rhs.x, y: lhs.y - rhs.y, z: lhs.z - rhs.z, w: lhs.w - rhs.w)
+proc `+`*(lhs, rhs: Tuple4): Tuple4 = Tuple4(x: lhs.x + rhs.x, y: lhs.y + rhs.y, z: lhs.z + rhs.z, w: lhs.w + rhs.w)
+proc `-`*(lhs, rhs: Tuple4): Tuple4 = Tuple4(x: lhs.x - rhs.x, y: lhs.y - rhs.y, z: lhs.z - rhs.z, w: lhs.w - rhs.w)
 proc `-`*(tup: Tuple4): Tuple4 = Tuple4(x: -tup.x, y: -tup.y, z: -tup.z, w: -tup.w)
 proc `*`*(tup: Tuple4, mag: float): Tuple4 = Tuple4(x: tup.x * mag, y: tup.y * mag, z: tup.z * mag, w: tup.w * mag)
 proc `/`*(tup: Tuple4, mag: float): Tuple4 = Tuple4(x: tup.x / mag, y: tup.y / mag, z: tup.z / mag, w: tup.w / mag)
@@ -21,8 +29,8 @@ proc magnitude*(tup: Tuple4): float = sqrt(tup.x * tup.x + tup.y * tup.y + tup.z
 proc normalize*(tup: Tuple4): Tuple4 = 
     let mag = tup.magnitude()
     Tuple4(x: tup.x / mag, y: tup.y / mag, z: tup.z / mag, w: tup.w / mag)
-proc dot*(lhs: Tuple4, rhs: Tuple4): float = lhs.x * rhs.x + lhs.y * rhs.y + lhs.z * rhs.z + lhs.w * rhs.w
-proc cross*(lhs: Tuple4, rhs: Tuple4): Tuple4 = vector(lhs.y * rhs.z - lhs.z * rhs.y, lhs.z * rhs.x - lhs.x * rhs.z, lhs.x * rhs.y - lhs.y * rhs.x)
+proc dot*(lhs, rhs: Tuple4): float = lhs.x * rhs.x + lhs.y * rhs.y + lhs.z * rhs.z + lhs.w * rhs.w
+proc cross*(lhs, rhs: Tuple4): Tuple4 = vector(lhs.y * rhs.z - lhs.z * rhs.y, lhs.z * rhs.x - lhs.x * rhs.z, lhs.x * rhs.y - lhs.y * rhs.x)
 
 when isMainModule:
     import unittest