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--[[
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
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