From 2abcf253ca9ed6bd6d9eb6c92d169171119255cb Mon Sep 17 00:00:00 2001
From: Lorenzo Cogotti <lcg@doublefourteen.io>
Date: Thu, 1 Jun 2023 23:12:43 +0200
Subject: [PATCH] [color] Add color operations and utilities.

---
 color.lua | 58 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)
 create mode 100644 color.lua

diff --git a/color.lua b/color.lua
new file mode 100644
index 0000000..c75d657
--- /dev/null
+++ b/color.lua
@@ -0,0 +1,58 @@
+--- Utility functions to manipulate colors.
+--
+-- Colors are represented as RGB or RGBA, each channel
+-- with values in range [0, 1].
+--
+-- @module gear.color
+-- @copyright 2023 The DoubleFourteen Code Forge
+-- @author Lorenzo Cogotti
+
+local Color = {}
+
+
+--- Darken RGB color by the specified amount.
+--
+-- @number r red channel
+-- @number g green channel
+-- @number b blue channel
+-- @number amount darken factor, must be in [0,1] range.
+function Color.darken(r, g, b, amount)
+	r = r * (1 - amount)
+	g = g * (1 - amount)
+	b = b * (1 - amount)
+
+	return r, g, b
+end
+
+--- Lighten RGB color by the specified amount.
+--
+-- @number r red channel
+-- @number g green channel
+-- @number b blue channel
+-- @number amount lightening factor, must be in [0,1] range.
+function Color.lighten(r, g, b, amount)
+	r = r + (1 - r) * amount
+	g = g + (1 - g) * amount
+	b = b + (1 - b) * amount
+
+	return r, g, b
+end
+
+--- Given two RGB colors, calculate fade by the specified amount.
+--
+-- @number cr first color, red channel
+-- @number cg first color, green channel
+-- @number cb first color, blue channel
+-- @number ar second color, red channel
+-- @number ag second color, green channel
+-- @number ab second color, blue channel
+-- @number amount fading factor, must be in [0,1] range.
+function Color.fade(cr, cg, cb, ar, ag, ab, amount)
+	cr = cr + (ar - cr) * amount
+	cg = cg + (ag - cg) * amount
+	cb = cb + (ab - cb) * amount
+
+	return cr, cg, cb
+end
+
+return Color