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