From 94221521819b566f6c4135d4d9fa7f84f11cf10c Mon Sep 17 00:00:00 2001
From: Max Cahill <1bardesign@gmail.com>
Date: Wed, 1 Apr 2020 20:58:18 +1100
Subject: [PATCH] [added] math.lerp_eps and matching vec2/vec3 methods; for
 ensuring a lerp actually reaches its destination once the delta doesn't
 matter

---
 math.lua | 10 ++++++++++
 vec2.lua | 10 ++++++++++
 vec3.lua | 11 +++++++++++
 3 files changed, 31 insertions(+)

diff --git a/math.lua b/math.lua
index 7c9def4..31713ce 100644
--- a/math.lua
+++ b/math.lua
@@ -55,6 +55,16 @@ function _math.lerp(a, b, t)
 	return a * (1.0 - t) + b * t
 end
 
+--linear interpolation with a minimum "final step" distance
+--useful for making sure dynamic lerps do actually reach their final destination
+function _math.lerp_eps(a, b, t, eps)
+	local v = math.lerp(a, b, t)
+	if math.abs(v - b) < eps then
+		v = b
+	end
+	return v
+end
+
 --classic smoothstep
 --(only "safe" for 0-1 range)
 function _math.smoothstep(v)
diff --git a/vec2.lua b/vec2.lua
index 02efe4e..4a92369 100644
--- a/vec2.lua
+++ b/vec2.lua
@@ -484,6 +484,16 @@ function vec2:lerp(other, amount)
 	return self:copy():lerpi(other, amount)
 end
 
+function vec2:lerp_epsi(other, amount, eps)
+	self.x = math.lerp_eps(self.x, other.x, amount, eps)
+	self.y = math.lerp_eps(self.y, other.y, amount, eps)
+	return self
+end
+
+function vec2:lerp_eps(other, amount, eps)
+	return self:copy():lerp_epsi(other, amount, eps)
+end
+
 -----------------------------------------------------------
 -- vector products and projections
 -----------------------------------------------------------
diff --git a/vec3.lua b/vec3.lua
index 38e5cdf..754998a 100644
--- a/vec3.lua
+++ b/vec3.lua
@@ -556,6 +556,17 @@ function vec3:lerp(other, amount)
 	return self:copy():lerpi(other, amount)
 end
 
+function vec3:lerp_epsi(other, amount, eps)
+	self.x = math.lerp_eps(self.x, other.x, amount, eps)
+	self.y = math.lerp_eps(self.y, other.y, amount, eps)
+	self.z = math.lerp_eps(self.z, other.z, amount, eps)
+	return self
+end
+
+function vec3:lerp_eps(other, amount, eps)
+	return self:copy():lerp_epsi(other, amount, eps)
+end
+
 -----------------------------------------------------------
 -- vector products and projections
 -----------------------------------------------------------