1 files changed, 129 insertions, 0 deletions
diff --git a/libs/moonshine/fog.lua b/libs/moonshine/fog.lua
new file mode 100644
index 0000000..9c90f9a
--- /dev/null
+++ b/libs/moonshine/fog.lua
@@ -0,0 +1,129 @@
+--[[
+Animated 2D Fog (procedural)
+Originally for Godot Engine by Gonkee https://www.youtube.com/watch?v=QEaTsz_0o44&t=6s
+
+Translated for löve by Brandon Blanker Lim-it @flamendless
+]]--
+
+--[[
+SAMPLE USAGE:
+local moonshine = require("moonshine")
+local effect
+
+local image, bg
+local image_data
+local shader_fog
+local time = 0
+
+function love.load()
+	image_data = love.image.newImageData(love.graphics.getWidth(), love.graphics.getHeight())
+	image = love.graphics.newImage(image_data)
+	bg = love.graphics.newImage("bg.png")
+	effect = moonshine(moonshine.effects.fog)
+	effect.fog.fog_color = {0.1, 0.0, 0.0}
+	effect.fog.speed = {0.2, 0.9}
+end
+
+function love.update(dt)
+	time = time + dt
+	effect.fog.time = time
+end
+
+function love.draw()
+	love.graphics.draw(bg)
+	effect(function()
+		love.graphics.draw(image)
+	end)
+end
+]]
+
+return function(moonshine)
+	local fog_color
+	local octaves
+	local speed
+	local time
+
+	local shader = love.graphics.newShader([[
+		extern vec3 fog_color = vec3(0.35, 0.48, 0.95);
+		extern int octaves = 4;
+		extern vec2 speed = vec2(0.0, 1.0);
+		extern float time;
+
+		float rand(vec2 coord)
+		{
+			return fract(sin(dot(coord, vec2(56, 78)) * 1000.0) * 1000.0);
+		}
+
+		float noise(vec2 coord)
+		{
+			vec2 i = floor(coord); //get the whole number
+			vec2 f = fract(coord); //get the fraction number
+			float a = rand(i); //top-left
+			float b = rand(i + vec2(1.0, 0.0)); //top-right
+			float c = rand(i + vec2(0.0, 1.0)); //bottom-left
+			float d = rand(i + vec2(1.0, 1.0)); //bottom-right
+			vec2 cubic = f * f * (3.0 - 2.0 * f);
+			return mix(a, b, cubic.x) + (c - a) * cubic.y * (1.0 - cubic.x) + (d - b) * cubic.x * cubic.y; //interpolate
+		}
+
+		float fbm(vec2 coord) //fractal brownian motion
+		{
+			float value = 0.0;
+			float scale = 0.5;
+			for (int i = 0; i < octaves; i++)
+			{
+				value += noise(coord) * scale;
+				coord *= 2.0;
+				scale *= 0.5;
+			}
+			return value;
+		}
+
+		vec4 effect(vec4 color, Image texture, vec2 tc, vec2 sc)
+		{
+			vec2 coord = tc * 20.0;
+			vec2 motion = vec2(fbm(coord + vec2(time * speed.x, time * speed.y)));
+			float final = fbm(coord + motion);
+			return vec4(fog_color, final * 0.5);
+		}
+	]])
+
+	local setters = {}
+
+	setters.fog_color = function(t)
+		assert(type(t) == "table", "Passed argument to fog_color must be a table containing 3 color values")
+		fog_color = t
+		shader:send("fog_color", fog_color)
+	end
+
+	setters.octaves = function(i)
+		assert(type(i) == "number", "Passed argument to octaves must be an integer")
+		octaves = i
+		shader:send("octaves", octaves)
+	end
+
+	setters.speed = function(t)
+		assert(type(t) == "table", "Passed argument to speed must be a table containing 2 values")
+		speed = t
+		shader:send("speed", speed)
+	end
+
+	setters.time = function(n)
+		assert(type(n) == "number", "Passed argument to time must be a number")
+		time = n
+		shader:send("time", time)
+	end
+
+	local defaults = {
+		fog_color = {0.35, 0.48, 0.95},
+		octaves = 4,
+		speed = {0.5, 0.5},
+	}
+
+	return moonshine.Effect({
+		name = "fog",
+		shader = shader,
+		setters = setters,
+		defaults = defaults,
+	})
+end